# HG changeset patch
# User henryjen
# Date 1544730666 28800
# Node ID b94283cb226baa47f87ede9d67a1ff4e5770c67f
# Parent  fd6de53a0d6e7c9084aca7582d7f98d51224d1ca# Parent  cc4098b3bc10d1c390384289025fea7b0d4b9e93
Merge

diff -r fd6de53a0d6e -r b94283cb226b make/autoconf/hotspot.m4
--- a/make/autoconf/hotspot.m4	Thu Dec 13 11:47:35 2018 -0800
+++ b/make/autoconf/hotspot.m4	Thu Dec 13 11:51:06 2018 -0800
@@ -327,7 +327,7 @@
 
   # Only enable Shenandoah on supported arches
   AC_MSG_CHECKING([if shenandoah can be built])
-  if test "x$OPENJDK_TARGET_CPU_ARCH" = "xx86" || test "x$OPENJDK_TARGET_CPU" = "xaarch64" ; then
+  if test "x$OPENJDK_TARGET_CPU" = "xx86_64" || test "x$OPENJDK_TARGET_CPU" = "xaarch64" ; then
     AC_MSG_RESULT([yes])
   else
     DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES shenandoahgc"
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/cpu/ppc/assembler_ppc.hpp
--- a/src/hotspot/cpu/ppc/assembler_ppc.hpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/cpu/ppc/assembler_ppc.hpp	Thu Dec 13 11:51:06 2018 -0800
@@ -539,6 +539,12 @@
     XVSUBDP_OPCODE = (60u << OPCODE_SHIFT |  104u << 3),
     XVMULSP_OPCODE = (60u << OPCODE_SHIFT |   80u << 3),
     XVMULDP_OPCODE = (60u << OPCODE_SHIFT |  112u << 3),
+    XVMADDASP_OPCODE=(60u << OPCODE_SHIFT |   65u << 3),
+    XVMADDADP_OPCODE=(60u << OPCODE_SHIFT |   97u << 3),
+    XVMSUBASP_OPCODE=(60u << OPCODE_SHIFT |   81u << 3),
+    XVMSUBADP_OPCODE=(60u << OPCODE_SHIFT |  113u << 3),
+    XVNMSUBASP_OPCODE=(60u<< OPCODE_SHIFT |  209u << 3),
+    XVNMSUBADP_OPCODE=(60u<< OPCODE_SHIFT |  241u << 3),
 
     // Deliver A Random Number (introduced with POWER9)
     DARN_OPCODE    = (31u << OPCODE_SHIFT |  755u << 1),
@@ -2227,6 +2233,12 @@
   inline void xvsubdp(  VectorSRegister d, VectorSRegister a, VectorSRegister b);
   inline void xvmulsp(  VectorSRegister d, VectorSRegister a, VectorSRegister b);
   inline void xvmuldp(  VectorSRegister d, VectorSRegister a, VectorSRegister b);
+  inline void xvmaddasp(VectorSRegister d, VectorSRegister a, VectorSRegister b);
+  inline void xvmaddadp(VectorSRegister d, VectorSRegister a, VectorSRegister b);
+  inline void xvmsubasp(VectorSRegister d, VectorSRegister a, VectorSRegister b);
+  inline void xvmsubadp(VectorSRegister d, VectorSRegister a, VectorSRegister b);
+  inline void xvnmsubasp(VectorSRegister d, VectorSRegister a, VectorSRegister b);
+  inline void xvnmsubadp(VectorSRegister d, VectorSRegister a, VectorSRegister b);
 
   // VSX Extended Mnemonics
   inline void xxspltd(  VectorSRegister d, VectorSRegister a, int x);
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/cpu/ppc/assembler_ppc.inline.hpp
--- a/src/hotspot/cpu/ppc/assembler_ppc.inline.hpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/cpu/ppc/assembler_ppc.inline.hpp	Thu Dec 13 11:51:06 2018 -0800
@@ -790,6 +790,12 @@
 inline void Assembler::xvsubdp( VectorSRegister d, VectorSRegister a, VectorSRegister b) { emit_int32( XVSUBDP_OPCODE | vsrt(d) | vsra(a) | vsrb(b)); }
 inline void Assembler::xvmulsp( VectorSRegister d, VectorSRegister a, VectorSRegister b) { emit_int32( XVMULSP_OPCODE | vsrt(d) | vsra(a) | vsrb(b)); }
 inline void Assembler::xvmuldp( VectorSRegister d, VectorSRegister a, VectorSRegister b) { emit_int32( XVMULDP_OPCODE | vsrt(d) | vsra(a) | vsrb(b)); }
+inline void Assembler::xvmaddasp( VectorSRegister d, VectorSRegister a, VectorSRegister b) { emit_int32( XVMADDASP_OPCODE  | vsrt(d) | vsra(a) | vsrb(b)); }
+inline void Assembler::xvmaddadp( VectorSRegister d, VectorSRegister a, VectorSRegister b) { emit_int32( XVMADDADP_OPCODE  | vsrt(d) | vsra(a) | vsrb(b)); }
+inline void Assembler::xvmsubasp( VectorSRegister d, VectorSRegister a, VectorSRegister b) { emit_int32( XVMSUBASP_OPCODE  | vsrt(d) | vsra(a) | vsrb(b)); }
+inline void Assembler::xvmsubadp( VectorSRegister d, VectorSRegister a, VectorSRegister b) { emit_int32( XVMSUBADP_OPCODE  | vsrt(d) | vsra(a) | vsrb(b)); }
+inline void Assembler::xvnmsubasp(VectorSRegister d, VectorSRegister a, VectorSRegister b) { emit_int32( XVNMSUBASP_OPCODE | vsrt(d) | vsra(a) | vsrb(b)); }
+inline void Assembler::xvnmsubadp(VectorSRegister d, VectorSRegister a, VectorSRegister b) { emit_int32( XVNMSUBADP_OPCODE | vsrt(d) | vsra(a) | vsrb(b)); }
 inline void Assembler::mtvrd(   VectorRegister d, Register a)               { emit_int32( MTVSRD_OPCODE  | vsrt(d->to_vsr()) | ra(a)); }
 inline void Assembler::mfvrd(   Register        a, VectorRegister d)         { emit_int32( MFVSRD_OPCODE  | vsrt(d->to_vsr()) | ra(a)); }
 inline void Assembler::mtvrwz(  VectorRegister  d, Register a)               { emit_int32( MTVSRWZ_OPCODE | vsrt(d->to_vsr()) | ra(a)); }
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/cpu/ppc/ppc.ad
--- a/src/hotspot/cpu/ppc/ppc.ad	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/cpu/ppc/ppc.ad	Thu Dec 13 11:51:06 2018 -0800
@@ -2257,6 +2257,9 @@
     return SuperwordUseVSX;
   case Op_PopCountVI:
     return (SuperwordUseVSX && UsePopCountInstruction);
+  case Op_FmaVF:
+  case Op_FmaVD:
+    return (SuperwordUseVSX && UseFMA);
   case Op_Digit:
   case Op_LowerCase:
   case Op_UpperCase:
@@ -14475,6 +14478,92 @@
   ins_pipe(pipe_class_default);
 %}
 
+// --------------------------------- FMA --------------------------------------
+// dst + src1 * src2
+instruct vfma4F(vecX dst, vecX src1, vecX src2) %{
+  match(Set dst (FmaVF dst (Binary src1 src2)));
+  predicate(n->as_Vector()->length() == 4);
+
+  format %{ "XVMADDASP   $dst, $src1, $src2" %}
+
+  size(4);
+  ins_encode %{
+    __ xvmaddasp($dst$$VectorSRegister, $src1$$VectorSRegister, $src2$$VectorSRegister);
+  %}
+  ins_pipe(pipe_class_default);
+%}
+
+// dst - src1 * src2
+instruct vfma4F_neg1(vecX dst, vecX src1, vecX src2) %{
+  match(Set dst (FmaVF dst (Binary (NegVF src1) src2)));
+  match(Set dst (FmaVF dst (Binary src1 (NegVF src2))));
+  predicate(n->as_Vector()->length() == 4);
+
+  format %{ "XVNMSUBASP   $dst, $src1, $src2" %}
+
+  size(4);
+  ins_encode %{
+    __ xvnmsubasp($dst$$VectorSRegister, $src1$$VectorSRegister, $src2$$VectorSRegister);
+  %}
+  ins_pipe(pipe_class_default);
+%}
+
+// - dst + src1 * src2
+instruct vfma4F_neg2(vecX dst, vecX src1, vecX src2) %{
+  match(Set dst (FmaVF (NegVF dst) (Binary src1 src2)));
+  predicate(n->as_Vector()->length() == 4);
+
+  format %{ "XVMSUBASP   $dst, $src1, $src2" %}
+
+  size(4);
+  ins_encode %{
+    __ xvmsubasp($dst$$VectorSRegister, $src1$$VectorSRegister, $src2$$VectorSRegister);
+  %}
+  ins_pipe(pipe_class_default);
+%}
+
+// dst + src1 * src2
+instruct vfma2D(vecX dst, vecX src1, vecX src2) %{
+  match(Set dst (FmaVD  dst (Binary src1 src2)));
+  predicate(n->as_Vector()->length() == 2);
+
+  format %{ "XVMADDADP   $dst, $src1, $src2" %}
+
+  size(4);
+  ins_encode %{
+    __ xvmaddadp($dst$$VectorSRegister, $src1$$VectorSRegister, $src2$$VectorSRegister);
+  %}
+  ins_pipe(pipe_class_default);
+%}
+
+// dst - src1 * src2
+instruct vfma2D_neg1(vecX dst, vecX src1, vecX src2) %{
+  match(Set dst (FmaVD  dst (Binary (NegVD src1) src2)));
+  match(Set dst (FmaVD  dst (Binary src1 (NegVD src2))));
+  predicate(n->as_Vector()->length() == 2);
+
+  format %{ "XVNMSUBADP   $dst, $src1, $src2" %}
+
+  size(4);
+  ins_encode %{
+    __ xvnmsubadp($dst$$VectorSRegister, $src1$$VectorSRegister, $src2$$VectorSRegister);
+  %}
+  ins_pipe(pipe_class_default);
+%}
+
+// - dst + src1 * src2
+instruct vfma2D_neg2(vecX dst, vecX src1, vecX src2) %{
+  match(Set dst (FmaVD (NegVD dst) (Binary src1 src2)));
+  predicate(n->as_Vector()->length() == 2);
+
+  format %{ "XVMSUBADP   $dst, $src1, $src2" %}
+
+  size(4);
+  ins_encode %{
+    __ xvmsubadp($dst$$VectorSRegister, $src1$$VectorSRegister, $src2$$VectorSRegister);
+  %}
+  ins_pipe(pipe_class_default);
+%}
 
 //----------Overflow Math Instructions-----------------------------------------
 
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/cpu/x86/macroAssembler_x86_aes.cpp
--- a/src/hotspot/cpu/x86/macroAssembler_x86_aes.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/cpu/x86/macroAssembler_x86_aes.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -29,6 +29,7 @@
 #include "runtime/stubRoutines.hpp"
 #include "macroAssembler_x86.hpp"
 
+#ifdef _LP64
 // Multiply 128 x 128 bits, using 4 pclmulqdq operations
 void MacroAssembler::schoolbookAAD(int i, Register htbl, XMMRegister data,
     XMMRegister tmp0, XMMRegister tmp1, XMMRegister tmp2, XMMRegister tmp3) {
@@ -319,4 +320,5 @@
     vpxor(xmm1, xmm1, xmm1, Assembler::AVX_128bit);
     vpxor(xmm3, xmm3, xmm3, Assembler::AVX_128bit);
     vpxor(xmm15, xmm15, xmm15, Assembler::AVX_128bit);
-}
\ No newline at end of file
+}
+#endif // _LP64
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/os/linux/os_linux.cpp
--- a/src/hotspot/os/linux/os_linux.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/os/linux/os_linux.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -1354,9 +1354,11 @@
 void os::abort(bool dump_core, void* siginfo, const void* context) {
   os::shutdown();
   if (dump_core) {
+#if INCLUDE_CDS
     if (UseSharedSpaces && DumpPrivateMappingsInCore) {
       ClassLoader::close_jrt_image();
     }
+#endif
 #ifndef PRODUCT
     fdStream out(defaultStream::output_fd());
     out.print_raw("Current thread is ");
@@ -5075,9 +5077,11 @@
     set_coredump_filter(DAX_SHARED_BIT);
   }
 
+#if INCLUDE_CDS
   if (UseSharedSpaces && DumpPrivateMappingsInCore) {
     set_coredump_filter(FILE_BACKED_PVT_BIT);
   }
+#endif
 
   return JNI_OK;
 }
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -939,9 +939,6 @@
   q = queues->claim_next();
   while (q != NULL) {
     if (CANCELLABLE && heap->check_cancelled_gc_and_yield()) {
-      ShenandoahCancelledTerminatorTerminator tt;
-      ShenandoahSuspendibleThreadSetLeaver stsl(ShenandoahSuspendibleWorkers);
-      while (!terminator->offer_termination(&tt));
       return;
     }
 
@@ -965,9 +962,6 @@
    */
   while (true) {
     if (CANCELLABLE && heap->check_cancelled_gc_and_yield()) {
-      ShenandoahCancelledTerminatorTerminator tt;
-      ShenandoahSuspendibleThreadSetLeaver stsl(ShenandoahSuspendibleWorkers);
-      while (!terminator->offer_termination(&tt));
       return;
     }
 
@@ -991,7 +985,8 @@
       // Need to leave the STS here otherwise it might block safepoints.
       ShenandoahSuspendibleThreadSetLeaver stsl(CANCELLABLE && ShenandoahSuspendibleWorkers);
       ShenandoahTerminationTimingsTracker term_tracker(worker_id);
-      if (terminator->offer_termination()) return;
+      ShenandoahTerminatorTerminator tt(heap);
+      if (terminator->offer_termination(&tt)) return;
     }
   }
 }
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/gc/shenandoah/shenandoahTaskqueue.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahTaskqueue.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/gc/shenandoah/shenandoahTaskqueue.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -49,28 +49,8 @@
   return true;
 }
 
-class ShenandoahOWSTTerminator: public OWSTTaskTerminator {
-public:
-  ShenandoahOWSTTerminator(uint n_threads, TaskQueueSetSuper* queue_set) :
-    OWSTTaskTerminator(n_threads, queue_set){ }
-
-protected:
-  bool exit_termination(size_t tasks, TerminatorTerminator* terminator);
-};
-
-bool ShenandoahOWSTTerminator::exit_termination(size_t tasks, TerminatorTerminator* terminator) {
-  ShenandoahTerminatorTerminator* t = (ShenandoahTerminatorTerminator*)terminator;
-  bool force = (t != NULL) && t->should_force_termination();
-  if (force) {
-    // Force termination : continue termination, even there are remaining tasks.
-    return false;
-  } else {
-    return OWSTTaskTerminator::exit_termination(tasks, terminator);
-  }
-}
-
 ShenandoahTaskTerminator::ShenandoahTaskTerminator(uint n_threads, TaskQueueSetSuper* queue_set) :
-  _terminator(new ShenandoahOWSTTerminator(n_threads, queue_set)) { }
+  _terminator(new OWSTTaskTerminator(n_threads, queue_set)) { }
 
 ShenandoahTaskTerminator::~ShenandoahTaskTerminator() {
   assert(_terminator != NULL, "Invariant");
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/gc/shenandoah/shenandoahTaskqueue.hpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahTaskqueue.hpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/gc/shenandoah/shenandoahTaskqueue.hpp	Thu Dec 13 11:51:06 2018 -0800
@@ -306,18 +306,12 @@
 };
 
 class ShenandoahTerminatorTerminator : public TerminatorTerminator {
+private:
+  ShenandoahHeap* _heap;
 public:
+  ShenandoahTerminatorTerminator(ShenandoahHeap* const heap) : _heap(heap) { }
   // return true, terminates immediately, even if there's remaining work left
-  virtual bool should_force_termination() { return false; }
-};
-
-class ShenandoahCancelledTerminatorTerminator : public ShenandoahTerminatorTerminator {
-  virtual bool should_exit_termination() {
-    return false;
-  }
-  virtual bool should_force_termination() {
-    return true;
-  }
+  virtual bool should_exit_termination() { return _heap->cancelled_gc(); }
 };
 
 class ShenandoahTaskTerminator : public StackObj {
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -498,10 +498,6 @@
   q = queues->claim_next();
   while (q != NULL) {
     if (_heap->check_cancelled_gc_and_yield(sts_yield)) {
-      ShenandoahCancelledTerminatorTerminator tt;
-      ShenandoahEvacOOMScopeLeaver oom_scope_leaver;
-      ShenandoahSuspendibleThreadSetLeaver stsl(sts_yield && ShenandoahSuspendibleWorkers);
-      while (!terminator->offer_termination(&tt));
       return;
     }
 
@@ -547,17 +543,15 @@
       ShenandoahEvacOOMScopeLeaver oom_scope_leaver;
       ShenandoahSuspendibleThreadSetLeaver stsl(sts_yield && ShenandoahSuspendibleWorkers);
       ShenandoahTerminationTimingsTracker term_tracker(worker_id);
-      if (terminator->offer_termination()) return;
+      ShenandoahTerminatorTerminator tt(_heap);
+
+      if (terminator->offer_termination(&tt)) return;
     }
   }
 }
 
 bool ShenandoahTraversalGC::check_and_handle_cancelled_gc(ShenandoahTaskTerminator* terminator, bool sts_yield) {
   if (_heap->cancelled_gc()) {
-    ShenandoahCancelledTerminatorTerminator tt;
-    ShenandoahEvacOOMScopeLeaver oom_scope_leaver;
-    ShenandoahSuspendibleThreadSetLeaver stsl(sts_yield && ShenandoahSuspendibleWorkers);
-    while (! terminator->offer_termination(&tt));
     return true;
   }
   return false;
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/jni/jfrJniMethod.cpp
--- a/src/hotspot/share/jfr/jni/jfrJniMethod.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/jfr/jni/jfrJniMethod.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -33,7 +33,7 @@
 #include "jfr/recorder/checkpoint/jfrMetadataEvent.hpp"
 #include "jfr/recorder/checkpoint/types/traceid/jfrTraceId.inline.hpp"
 #include "jfr/recorder/repository/jfrRepository.hpp"
-#include "jfr/recorder/repository/jfrChunkSizeNotifier.hpp"
+#include "jfr/recorder/repository/jfrChunkRotation.hpp"
 #include "jfr/recorder/repository/jfrChunkWriter.hpp"
 #include "jfr/recorder/service/jfrOptionSet.hpp"
 #include "jfr/recorder/stacktrace/jfrStackTraceRepository.hpp"
@@ -114,7 +114,7 @@
 NO_TRANSITION_END
 
 NO_TRANSITION(void, jfr_set_file_notification(JNIEnv* env, jobject jvm, jlong threshold))
-  JfrChunkSizeNotifier::set_chunk_size_threshold((size_t)threshold);
+  JfrChunkRotation::set_threshold((intptr_t)threshold);
 NO_TRANSITION_END
 
 NO_TRANSITION(void, jfr_set_sample_threads(JNIEnv* env, jobject jvm, jboolean sampleThreads))
@@ -173,6 +173,9 @@
   return JfrEventSetting::set_cutoff(event_type_id, cutoff_ticks) ? JNI_TRUE : JNI_FALSE;
 NO_TRANSITION_END
 
+NO_TRANSITION(jboolean, jfr_should_rotate_disk(JNIEnv* env, jobject jvm))
+  return JfrChunkRotation::should_rotate() ? JNI_TRUE : JNI_FALSE;
+NO_TRANSITION_END
 
 /*
  * JVM_ENTRY_NO_ENV entries
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/jni/jfrJniMethod.hpp
--- a/src/hotspot/share/jfr/jni/jfrJniMethod.hpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/jfr/jni/jfrJniMethod.hpp	Thu Dec 13 11:51:06 2018 -0800
@@ -129,6 +129,9 @@
 
 void JNICALL jfr_emit_old_object_samples(JNIEnv* env, jobject jvm, jlong cutoff_ticks, jboolean);
 
+jboolean JNICALL jfr_should_rotate_disk(JNIEnv* env, jobject jvm);
+
+
 #ifdef __cplusplus
 }
 #endif
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/jni/jfrJniMethodRegistration.cpp
--- a/src/hotspot/share/jfr/jni/jfrJniMethodRegistration.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/jfr/jni/jfrJniMethodRegistration.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -78,7 +78,8 @@
       (char*)"setForceInstrumentation", (char*)"(Z)V", (void*)jfr_set_force_instrumentation,
       (char*)"getUnloadedEventClassCount", (char*)"()J", (void*)jfr_get_unloaded_event_classes_count,
       (char*)"setCutoff", (char*)"(JJ)Z", (void*)jfr_set_cutoff,
-      (char*)"emitOldObjectSamples", (char*)"(JZ)V", (void*)jfr_emit_old_object_samples
+      (char*)"emitOldObjectSamples", (char*)"(JZ)V", (void*)jfr_emit_old_object_samples,
+      (char*)"shouldRotateDisk", (char*)"()Z", (void*)jfr_should_rotate_disk
     };
 
     const size_t method_array_length = sizeof(method) / sizeof(JNINativeMethod);
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/leakprofiler/emitEventOperation.cpp
--- a/src/hotspot/share/jfr/leakprofiler/emitEventOperation.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/jfr/leakprofiler/emitEventOperation.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -185,7 +185,7 @@
   if (object->is_array()) {
     return arrayOop(object)->length();
   }
-  return -1;
+  return min_jint;
 }
 
 void EmitEventOperation::write_event(const ObjectSample* sample, EdgeStore* edge_store) {
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/metadata/metadata.xml
--- a/src/hotspot/share/jfr/metadata/metadata.xml	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/jfr/metadata/metadata.xml	Thu Dec 13 11:51:06 2018 -0800
@@ -65,19 +65,19 @@
     <Field type="InflateCause" name="cause" label="Monitor Inflation Cause" description="Cause of inflation" />
   </Event>
 
-  <Event name="BiasedLockRevocation" category="Java Application" label="Biased Lock Revocation" description="Revoked bias of object" thread="true"
+  <Event name="BiasedLockRevocation" category="Java Virtual Machine, Runtime" label="Biased Lock Revocation" description="Revoked bias of object" thread="true"
     stackTrace="true">
     <Field type="Class" name="lockClass" label="Lock Class" description="Class of object whose biased lock was revoked" />
     <Field type="ulong" name="safepointId" label="Safepoint Identifier" relation="SafepointId" />
     <Field type="Thread" name="previousOwner" label="Previous Owner" description="Thread owning the bias before revocation" />
   </Event>
 
-  <Event name="BiasedLockSelfRevocation" category="Java Application" label="Biased Lock Self Revocation" description="Revoked bias of object biased towards own thread"
+  <Event name="BiasedLockSelfRevocation" category="Java Virtual Machine, Runtime" label="Biased Lock Self Revocation" description="Revoked bias of object biased towards own thread"
     thread="true" stackTrace="true">
     <Field type="Class" name="lockClass" label="Lock Class" description="Class of object whose biased lock was revoked" />
   </Event>
 
-  <Event name="BiasedLockClassRevocation" category="Java Application" label="Biased Lock Class Revocation" description="Revoked biases for all instances of a class"
+  <Event name="BiasedLockClassRevocation" category="Java Virtual Machine, Runtime" label="Biased Lock Class Revocation" description="Revoked biases for all instances of a class"
     thread="true" stackTrace="true">
     <Field type="Class" name="revokedClass" label="Revoked Class" description="Class whose biased locks were revoked" />
     <Field type="boolean" name="disableBiasing" label="Disable Further Biasing" description="Whether further biasing for instances of this class will be allowed" />
@@ -350,7 +350,7 @@
     <Field type="ulong" contentType="bytes" name="recentMutatorAllocationSize" label="Recent Mutator Allocation Size"
       description="Mutator allocation during mutator operation in the most recent interval" />
     <Field type="long" contentType="millis" name="recentMutatorDuration" label="Recent Mutator Duration" description="Time the mutator ran in the most recent interval" />
-    <Field type="double" name="recentAllocationRate" label="Recent Allocation Rate" description="Allocation rate of the mutator in the most recent interval in bytes/second" />
+    <Field type="double" contentType="bytes-per-second" name="recentAllocationRate" label="Recent Allocation Rate" description="Allocation rate of the mutator in the most recent interval in bytes/second" />
     <Field type="long" contentType="millis" name="lastMarkingDuration" label="Last Marking Duration" description="Last time from the end of the last initial mark to the first mixed GC" />
   </Event>
 
@@ -362,7 +362,7 @@
     <Field type="ulong" contentType="bytes" name="ihopTargetOccupancy" label="IHOP Target Occupancy" description="Internal target old generation occupancy to reach at the start of mixed GC" />
     <Field type="ulong" contentType="bytes" name="currentOccupancy" label="Current Occupancy" description="Current old generation occupancy" />
     <Field type="ulong" contentType="bytes" name="additionalBufferSize" label="Additional Buffer" description="Additional buffer size" experimental="true" />
-    <Field type="double" name="predictedAllocationRate" label="Predicted Allocation Rate" description="Current predicted allocation rate for the mutator in bytes/second" />
+    <Field type="double" contentType="bytes-per-second" name="predictedAllocationRate" label="Predicted Allocation Rate" description="Current predicted allocation rate for the mutator in bytes/second" />
     <Field type="long" contentType="millis" name="predictedMarkingDuration" label="Predicted Marking Duration"
       description="Current predicted time from the end of the last initial mark to the first mixed GC" />
     <Field type="boolean" name="predictionActive" label="Prediction Active" description="Indicates whether the adaptive IHOP prediction is active" />
@@ -564,9 +564,9 @@
       relation="SafepointId" />
   </Event>
 
-  <Event name="Shutdown" category="Java Virtual Machine, Runtime" label="VM Shutdown" description="VM shutting down" thread="true" stackTrace="true"
+  <Event name="Shutdown" category="Java Virtual Machine, Runtime" label="JVM Shutdown" description="JVM shutting down" thread="true" stackTrace="true"
     startTime="false">
-    <Field type="string" name="reason" label="Reason" description="Reason for VM shutdown" />
+    <Field type="string" name="reason" label="Reason" description="Reason for JVM shutdown" />
   </Event>
 
   <Event name="ObjectAllocationInNewTLAB" category="Java Application" label="Allocation in new TLAB" description="Allocation in new Thread Local Allocation Buffer"
@@ -582,7 +582,7 @@
     <Field type="ulong" contentType="bytes" name="allocationSize" label="Allocation Size" />
   </Event>
 
-  <Event name="OldObjectSample" category="Java Application" label="Old Object Sample" description="A potential memory leak" stackTrace="true" thread="true"
+  <Event name="OldObjectSample" category="Java Virtual Machine, Profiling" label="Old Object Sample" description="A potential memory leak" stackTrace="true" thread="true"
     startTime="false" cutoff="true">
     <Field type="Ticks" name="allocationTime" label="Allocation Time" />
     <Field type="ulong" contentType="bytes" name="lastKnownHeapUsage" label="Last Known Heap Usage" />
@@ -647,8 +647,8 @@
   <Event name="CPUTimeStampCounter" category="Operating System, Processor" label="CPU Time Stamp Counter" period="endChunk">
     <Field type="boolean" name="fastTimeEnabled" label="Fast Time" />
     <Field type="boolean" name="fastTimeAutoEnabled" label="Trusted Platform" />
-    <Field type="long" name="osFrequency" label="OS Frequency Per Second" />
-    <Field type="long" name="fastTimeFrequency" label="Fast Time Frequency per Second" />
+    <Field type="long" contentType="hertz" name="osFrequency" label="OS Frequency" />
+    <Field type="long" contentType="hertz" name="fastTimeFrequency" label="Fast Time Frequency" />
   </Event>
 
   <Event name="CPULoad" category="Operating System, Processor" label="CPU Load" description="OS CPU Load" period="everyChunk">
@@ -663,13 +663,13 @@
   </Event>
 
   <Event name="ThreadContextSwitchRate" category="Operating System, Processor" label="Thread Context Switch Rate" period="everyChunk">
-    <Field type="float" name="switchRate" label="Switch Rate" description="Number of context switches per second" />
+    <Field type="float" contentType="hertz" name="switchRate" label="Switch Rate" description="Number of context switches per second" />
   </Event>
 
   <Event name="NetworkUtilization" category="Operating System, Network" label="Network Utilization" period="everyChunk">
     <Field type="NetworkInterfaceName" name="networkInterface" label="Network Interface" description="Network Interface Name"/>
-    <Field type="long" contentType="bytes" name="readRate" label="Read Rate" description="Number of incoming bytes per second"/>
-    <Field type="long" contentType="bytes" name="writeRate" label="Write Rate" description="Number of outgoing bytes per second"/>
+    <Field type="long" contentType="bits-per-second" name="readRate" label="Read Rate" description="Number of incoming bits per second"/>
+    <Field type="long" contentType="bits-per-second" name="writeRate" label="Write Rate" description="Number of outgoing bits per second"/>
   </Event>
 
   <Event name="JavaThreadStatistics" category="Java Application, Statistics" label="Java Thread Statistics" period="everyChunk">
@@ -687,7 +687,7 @@
   <Event name="ClassLoaderStatistics" category="Java Application, Statistics" label="Class Loader Statistics" period="everyChunk">
     <Field type="ClassLoader" name="classLoader" label="Class Loader" />
     <Field type="ClassLoader" name="parentClassLoader" label="Parent Class Loader" />
-    <Field type="ulong" contentType="address" name="classLoaderData" label="ClassLoaderData pointer" description="Pointer to the ClassLoaderData structure in the JVM" />
+    <Field type="ulong" contentType="address" name="classLoaderData" label="ClassLoaderData Pointer" description="Pointer to the ClassLoaderData structure in the JVM" />
     <Field type="long" name="classCount" label="Classes" description="Number of loaded classes" />
     <Field type="ulong" contentType="bytes" name="chunkSize" label="Total Chunk Size" description="Total size of all allocated metaspace chunks (each chunk has several blocks)" />
     <Field type="ulong" contentType="bytes" name="blockSize" label="Total Block Size" description="Total size of all allocated metaspace blocks (each chunk has several blocks)" />
@@ -741,8 +741,7 @@
   <Event name="ModuleExport" category="Java Virtual Machine, Runtime, Modules" label="Module Export" thread="false" period="everyChunk">
     <Field type="Package" name="exportedPackage" label="Exported Package" />
     <Field type="Module" name="targetModule" label="Target Module"
-      description="Module to which the package is qualifiedly exported.
-             If null, the package is unqualifiedly exported" />
+      description="Module to which the package is qualifiedly exported. If null or N/A, the package is unqualifiedly exported" />
   </Event>
 
   <Event name="CompilerStatistics" category="Java Virtual Machine, Compiler" label="Compiler Statistics" thread="false" period="everyChunk" startTime="false">
@@ -1096,7 +1095,7 @@
     <Field type="OldObjectArray" name="array" label="Array Information" description="Array or null if it is not an array" />
     <Field type="OldObjectField" name="field" label="Field Information" description="Field or null if it is an array" />
     <Field type="OldObject" name="object" label="Object" description="Object holder for this reference" />
-    <Field type="int" name="skip" label="Skip value" description="The object is this many hops away" />
+    <Field type="int" name="skip" label="Skip Value" description="The object is this many hops away" />
   </Type>
 
   <Type name="StackFrame">
@@ -1134,13 +1133,16 @@
   <XmlType name="char" javaType="char" parameterType="char" fieldType="char"/> 
   <XmlType name="string" javaType="java.lang.String" parameterType="const char*" fieldType="const char*"/> 
  
-  <XmlContentType name="bytes" annotationType="jdk.jfr.DataAmount" annotationValue="BYTES" />
-  <XmlContentType name="tickstamp" annotationType="jdk.jfr.Timestamp" annotationValue="TICKS" />
-  <XmlContentType name="epochmillis" annotationType="jdk.jfr.Timestamp" annotationValue="MILLISECONDS_SINCE_EPOCH" />
-  <XmlContentType name="tickspan" annotationType="jdk.jfr.Timespan" annotationValue="TICKS" />
-  <XmlContentType name="address" annotationType="jdk.jfr.MemoryAddress" />
-  <XmlContentType name="percentage" annotationType="jdk.jfr.Percentage" />
-  <XmlContentType name="millis" annotationType="jdk.jfr.Timespan" annotationValue="MILLISECONDS" />
-  <XmlContentType name="nanos" annotationType="jdk.jfr.Timespan" annotationValue="NANOSECONDS" />
-  
+  <XmlContentType name="bytes" annotation="jdk.jfr.DataAmount(BYTES)" />
+  <XmlContentType name="tickstamp" annotation="jdk.jfr.Timestamp(TICKS)" />
+  <XmlContentType name="epochmillis" annotation="jdk.jfr.Timestamp(MILLISECONDS_SINCE_EPOCH)" />
+  <XmlContentType name="tickspan" annotation="jdk.jfr.Timespan(TICKS)" />
+  <XmlContentType name="address" annotation="jdk.jfr.MemoryAddress" />
+  <XmlContentType name="percentage" annotation="jdk.jfr.Percentage" />
+  <XmlContentType name="millis" annotation="jdk.jfr.Timespan(MILLISECONDS)" />
+  <XmlContentType name="nanos" annotation="jdk.jfr.Timespan(NANOSECONDS)" />
+  <XmlContentType name="hertz" annotation="jdk.jfr.Frequency" />
+  <XmlContentType name="bytes-per-second" annotation="jdk.jfr.DataAmount(BYTES), jdk.jfr.Frequency" />
+  <XmlContentType name="bits-per-second" annotation="jdk.jfr.DataAmount(BITS), jdk.jfr.Frequency" />
+ 
 </Metadata>
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/metadata/metadata.xsd
--- a/src/hotspot/share/jfr/metadata/metadata.xsd	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/jfr/metadata/metadata.xsd	Thu Dec 13 11:51:06 2018 -0800
@@ -107,8 +107,7 @@
           <xs:element name="XmlContentType">
             <xs:complexType>
               <xs:attribute name="name" type="xs:NMTOKEN" use="required" />
-              <xs:attribute name="annotationType" type="xs:NMTOKEN" use="required" />
-              <xs:attribute name="annotationValue" type="xs:string" use="optional" />
+              <xs:attribute name="annotation" type="xs:string" use="required" />
             </xs:complexType>
           </xs:element>
           <xs:element name="Relation">
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/periodic/jfrNetworkUtilization.cpp
--- a/src/hotspot/share/jfr/periodic/jfrNetworkUtilization.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/jfr/periodic/jfrNetworkUtilization.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -174,8 +174,8 @@
         event.set_starttime(cur_time);
         event.set_endtime(cur_time);
         event.set_networkInterface(entry.id);
-        event.set_readRate(read_rate);
-        event.set_writeRate(write_rate);
+        event.set_readRate(8 * read_rate);
+        event.set_writeRate(8 * write_rate);
         event.commit();
       }
       // update existing entry with new values
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/recorder/repository/jfrChunkRotation.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/jfr/recorder/repository/jfrChunkRotation.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "jfr/jni/jfrJavaSupport.hpp"
+#include "jfr/recorder/repository/jfrChunkRotation.hpp"
+#include "jfr/recorder/repository/jfrChunkWriter.hpp"
+
+static jobject chunk_monitor = NULL;
+static intptr_t threshold = 0;
+static bool rotate = false;
+
+static jobject install_chunk_monitor(Thread* thread) {
+  assert(chunk_monitor == NULL, "invariant");
+  // read static field
+  HandleMark hm(thread);
+  static const char klass[] = "jdk/jfr/internal/JVM";
+  static const char field[] = "FILE_DELTA_CHANGE";
+  static const char signature[] = "Ljava/lang/Object;";
+  JavaValue result(T_OBJECT);
+  JfrJavaArguments field_args(&result, klass, field, signature, thread);
+  JfrJavaSupport::get_field_global_ref(&field_args, thread);
+  chunk_monitor = result.get_jobject();
+  return chunk_monitor;
+}
+
+// lazy install
+static jobject get_chunk_monitor(Thread* thread) {
+  return chunk_monitor != NULL ? chunk_monitor : install_chunk_monitor(thread);
+}
+
+static void notify() {
+  Thread* const thread = Thread::current();
+  JfrJavaSupport::notify_all(get_chunk_monitor(thread), thread);
+}
+
+void JfrChunkRotation::evaluate(const JfrChunkWriter& writer) {
+  assert(threshold > 0, "invariant");
+  if (rotate) {
+    // already in progress
+    return;
+  }
+  assert(!rotate, "invariant");
+  if (writer.size_written() > threshold) {
+    rotate = true;
+    notify();
+  }
+}
+
+bool JfrChunkRotation::should_rotate() {
+  return rotate;
+}
+
+void JfrChunkRotation::on_rotation() {
+  rotate = false;
+}
+
+void JfrChunkRotation::set_threshold(intptr_t bytes) {
+  threshold = bytes;
+}
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/recorder/repository/jfrChunkRotation.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/jfr/recorder/repository/jfrChunkRotation.hpp	Thu Dec 13 11:51:06 2018 -0800
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_JFR_RECORDER_REPOSITORY_JFRCHUNKROTATION_HPP
+#define SHARE_VM_JFR_RECORDER_REPOSITORY_JFRCHUNKROTATION_HPP
+
+#include "memory/allocation.hpp"
+
+class JfrChunkWriter;
+
+//
+// Responsible for notifications about current chunk size now exceeding threshold.
+// This is a means to initiate a chunk rotation on the basis of the size written.
+//
+class JfrChunkRotation : AllStatic {
+ public:
+  static void evaluate(const JfrChunkWriter& writer);
+  static void set_threshold(intptr_t bytes);
+  static bool should_rotate();
+  static void on_rotation();
+};
+
+#endif // SHARE_VM_JFR_RECORDER_REPOSITORY_JFRCHUNKROTATION_HPP
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/recorder/repository/jfrChunkSizeNotifier.cpp
--- a/src/hotspot/share/jfr/recorder/repository/jfrChunkSizeNotifier.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,73 +0,0 @@
-/*
- * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- *
- */
-
-#include "precompiled.hpp"
-#include "jfr/jni/jfrJavaSupport.hpp"
-#include "jfr/recorder/repository/jfrChunkWriter.hpp"
-#include "jfr/recorder/repository/jfrChunkSizeNotifier.hpp"
-
-size_t JfrChunkSizeNotifier::_chunk_size_threshold = 0;
-
-void JfrChunkSizeNotifier::set_chunk_size_threshold(size_t bytes) {
-  _chunk_size_threshold = bytes;
-}
-
-size_t JfrChunkSizeNotifier::chunk_size_threshold() {
-  return _chunk_size_threshold;
-}
-
-static jobject new_chunk_monitor = NULL;
-
-// lazy install
-static jobject get_new_chunk_monitor(Thread* thread) {
-  static bool initialized = false;
-  if (initialized) {
-    assert(new_chunk_monitor != NULL, "invariant");
-    return new_chunk_monitor;
-  }
-  assert(new_chunk_monitor == NULL, "invariant");
-  // read static field
-  HandleMark hm(thread);
-  static const char klass[] = "jdk/jfr/internal/JVM";
-  static const char field[] = "FILE_DELTA_CHANGE";
-  static const char signature[] = "Ljava/lang/Object;";
-  JavaValue result(T_OBJECT);
-  JfrJavaArguments field_args(&result, klass, field, signature, thread);
-  JfrJavaSupport::get_field_global_ref(&field_args, thread);
-  new_chunk_monitor = result.get_jobject();
-  initialized = new_chunk_monitor != NULL;
-  return new_chunk_monitor;
-}
-
-void JfrChunkSizeNotifier::notify() {
-  Thread* const thread = Thread::current();
-  JfrJavaSupport::notify_all(get_new_chunk_monitor(thread), thread);
-}
-
-void JfrChunkSizeNotifier::release_monitor() {
-  if (new_chunk_monitor != NULL) {
-    JfrJavaSupport::destroy_global_jni_handle(new_chunk_monitor);
-    new_chunk_monitor = NULL;
-  }
-}
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/recorder/repository/jfrChunkSizeNotifier.hpp
--- a/src/hotspot/share/jfr/recorder/repository/jfrChunkSizeNotifier.hpp	Thu Dec 13 11:47:35 2018 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,45 +0,0 @@
-/*
- * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- *
- */
-
-#ifndef SHARE_VM_JFR_RECORDER_REPOSITORY_JFRRCHUNKSIZENOTIFIER_HPP
-#define SHARE_VM_JFR_RECORDER_REPOSITORY_JFRRCHUNKSIZENOTIFIER_HPP
-
-#include "memory/allocation.hpp"
-
-//
-// Responsible for notifications about current chunk size now exceeding threshold.
-// This is a means to initiate a chunk rotation on the basis of size written.
-//
-class JfrChunkSizeNotifier : AllStatic {
-  friend class JfrRecorder;
- private:
-  static size_t _chunk_size_threshold;
-  static void release_monitor();
- public:
-  static void set_chunk_size_threshold(size_t bytes);
-  static size_t chunk_size_threshold();
-  static void notify();
-};
-
-#endif // SHARE_VM_JFR_RECORDER_REPOSITORY_JFRRCHUNKSIZENOTIFIER_HPP
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/jfr/recorder/service/jfrRecorderService.cpp
--- a/src/hotspot/share/jfr/recorder/service/jfrRecorderService.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/jfr/recorder/service/jfrRecorderService.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -28,7 +28,7 @@
 #include "jfr/recorder/jfrRecorder.hpp"
 #include "jfr/recorder/checkpoint/jfrCheckpointManager.hpp"
 #include "jfr/recorder/checkpoint/jfrMetadataEvent.hpp"
-#include "jfr/recorder/repository/jfrChunkSizeNotifier.hpp"
+#include "jfr/recorder/repository/jfrChunkRotation.hpp"
 #include "jfr/recorder/repository/jfrChunkWriter.hpp"
 #include "jfr/recorder/repository/jfrRepository.hpp"
 #include "jfr/recorder/service/jfrPostBox.hpp"
@@ -340,6 +340,7 @@
 void JfrRecorderService::open_new_chunk(bool vm_error) {
   assert(!_chunkwriter.is_valid(), "invariant");
   assert(!JfrStream_lock->owned_by_self(), "invariant");
+  JfrChunkRotation::on_rotation();
   MutexLockerEx stream_lock(JfrStream_lock, Mutex::_no_safepoint_check_flag);
   if (!_repository.open_chunk(vm_error)) {
     assert(!_chunkwriter.is_valid(), "invariant");
@@ -535,8 +536,5 @@
 }
 
 void JfrRecorderService::evaluate_chunk_size_for_rotation() {
-  const size_t size_written = _chunkwriter.size_written();
-  if (size_written > JfrChunkSizeNotifier::chunk_size_threshold()) {
-    JfrChunkSizeNotifier::notify();
-  }
+  JfrChunkRotation::evaluate(_chunkwriter);
 }
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/runtime/globals.hpp
--- a/src/hotspot/share/runtime/globals.hpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/runtime/globals.hpp	Thu Dec 13 11:51:06 2018 -0800
@@ -501,6 +501,13 @@
   diagnostic(bool, AbortVMOnSafepointTimeout, false,                        \
           "Abort upon failure to reach safepoint (see SafepointTimeout)")   \
                                                                             \
+  diagnostic(bool, AbortVMOnVMOperationTimeout, false,                      \
+          "Abort upon failure to complete VM operation promptly")           \
+                                                                            \
+  diagnostic(intx, AbortVMOnVMOperationTimeoutDelay, 1000,                  \
+          "Delay in milliseconds for option AbortVMOnVMOperationTimeout")   \
+          range(0, max_intx)                                                \
+                                                                            \
   /* 50 retries * (5 * current_retry_count) millis = ~6.375 seconds */      \
   /* typically, at most a few retries are needed                    */      \
   product(intx, SuspendRetryCount, 50,                                      \
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/runtime/vmThread.cpp
--- a/src/hotspot/share/runtime/vmThread.cpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/runtime/vmThread.cpp	Thu Dec 13 11:51:06 2018 -0800
@@ -28,6 +28,7 @@
 #include "jfr/jfrEvents.hpp"
 #include "jfr/support/jfrThreadId.hpp"
 #include "logging/log.hpp"
+#include "logging/logStream.hpp"
 #include "logging/logConfiguration.hpp"
 #include "memory/resourceArea.hpp"
 #include "oops/method.hpp"
@@ -197,6 +198,32 @@
   drain_list_oops_do(f);
 }
 
+//------------------------------------------------------------------------------------------------------------------
+// Timeout machinery
+
+void VMOperationTimeoutTask::task() {
+  assert(AbortVMOnVMOperationTimeout, "only if enabled");
+  if (is_armed()) {
+    jlong delay = (os::javaTimeMillis() - _arm_time);
+    if (delay > AbortVMOnVMOperationTimeoutDelay) {
+      fatal("VM operation took too long: " SIZE_FORMAT " ms (timeout: " SIZE_FORMAT " ms)",
+            delay, AbortVMOnVMOperationTimeoutDelay);
+    }
+  }
+}
+
+bool VMOperationTimeoutTask::is_armed() {
+  return OrderAccess::load_acquire(&_armed) != 0;
+}
+
+void VMOperationTimeoutTask::arm() {
+  _arm_time = os::javaTimeMillis();
+  OrderAccess::release_store_fence(&_armed, 1);
+}
+
+void VMOperationTimeoutTask::disarm() {
+  OrderAccess::release_store_fence(&_armed, 0);
+}
 
 //------------------------------------------------------------------------------------------------------------------
 // Implementation of VMThread stuff
@@ -209,12 +236,28 @@
 VMOperationQueue* VMThread::_vm_queue           = NULL;
 PerfCounter*      VMThread::_perf_accumulated_vm_operation_time = NULL;
 const char*       VMThread::_no_op_reason       = NULL;
+VMOperationTimeoutTask* VMThread::_timeout_task = NULL;
 
 
 void VMThread::create() {
   assert(vm_thread() == NULL, "we can only allocate one VMThread");
   _vm_thread = new VMThread();
 
+  if (AbortVMOnVMOperationTimeout) {
+    // Make sure we call the timeout task frequently enough, but not too frequent.
+    // Try to make the interval 10% of the timeout delay, so that we miss the timeout
+    // by those 10% at max. Periodic task also expects it to fit min/max intervals.
+    size_t interval = (size_t)AbortVMOnVMOperationTimeoutDelay / 10;
+    interval = interval / PeriodicTask::interval_gran * PeriodicTask::interval_gran;
+    interval = MAX2<size_t>(interval, PeriodicTask::min_interval);
+    interval = MIN2<size_t>(interval, PeriodicTask::max_interval);
+
+    _timeout_task = new VMOperationTimeoutTask(interval);
+    _timeout_task->enroll();
+  } else {
+    assert(_timeout_task == NULL, "sanity");
+  }
+
   // Create VM operation queue
   _vm_queue = new VMOperationQueue();
   guarantee(_vm_queue != NULL, "just checking");
@@ -492,6 +535,11 @@
         _vm_queue->set_drain_list(safepoint_ops); // ensure ops can be scanned
 
         SafepointSynchronize::begin();
+
+        if (_timeout_task != NULL) {
+          _timeout_task->arm();
+        }
+
         evaluate_operation(_cur_vm_operation);
         // now process all queued safepoint ops, iteratively draining
         // the queue until there are none left
@@ -533,6 +581,10 @@
 
         _vm_queue->set_drain_list(NULL);
 
+        if (_timeout_task != NULL) {
+          _timeout_task->disarm();
+        }
+
         // Complete safepoint synchronization
         SafepointSynchronize::end();
 
diff -r fd6de53a0d6e -r b94283cb226b src/hotspot/share/runtime/vmThread.hpp
--- a/src/hotspot/share/runtime/vmThread.hpp	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/hotspot/share/runtime/vmThread.hpp	Thu Dec 13 11:51:06 2018 -0800
@@ -27,6 +27,7 @@
 
 #include "runtime/perfData.hpp"
 #include "runtime/thread.hpp"
+#include "runtime/task.hpp"
 #include "runtime/vmOperations.hpp"
 
 //
@@ -84,6 +85,26 @@
 };
 
 
+// VM operation timeout handling: warn or abort the VM when VM operation takes
+// too long. Periodic tasks do not participate in safepoint protocol, and therefore
+// can fire when application threads are stopped.
+
+class VMOperationTimeoutTask : public PeriodicTask {
+private:
+  volatile int _armed;
+  jlong _arm_time;
+
+public:
+  VMOperationTimeoutTask(size_t interval_time) :
+          PeriodicTask(interval_time), _armed(0), _arm_time(0) {}
+
+  virtual void task();
+
+  bool is_armed();
+  void arm();
+  void disarm();
+};
+
 //
 // A single VMThread (the primordial thread) spawns all other threads
 // and is itself used by other threads to offload heavy vm operations
@@ -101,6 +122,8 @@
 
   static const char* _no_op_reason;
 
+  static VMOperationTimeoutTask* _timeout_task;
+
   static bool no_op_safepoint_needed(bool check_time);
 
   void evaluate_operation(VM_Operation* op);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/com/sun/java/util/jar/pack/Attribute.java
--- a/src/java.base/share/classes/com/sun/java/util/jar/pack/Attribute.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/com/sun/java/util/jar/pack/Attribute.java	Thu Dec 13 11:51:06 2018 -0800
@@ -996,7 +996,7 @@
                             endp = cstr.indexOf(',', cp);
                             if (endp < 0)  endp = cstrlen;
                             String cstr1 = cstr.substring(cp, endp);
-                            if (cstr1.length() == 0)
+                            if (cstr1.isEmpty())
                                 cstr1 = "empty";  // will fail parse
                             int value0, value1;
                             // Check for a case range (new in 1.6).
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/com/sun/java/util/jar/pack/Driver.java
--- a/src/java.base/share/classes/com/sun/java/util/jar/pack/Driver.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/com/sun/java/util/jar/pack/Driver.java	Thu Dec 13 11:51:06 2018 -0800
@@ -279,7 +279,7 @@
         junpack.properties().putAll(engProps);
         if (doRepack && newfile.equals(jarfile)) {
             String zipc = getZipComment(jarfile);
-            if (verbose && zipc.length() > 0)
+            if (verbose && !zipc.isEmpty())
                 System.out.println(MessageFormat.format(RESOURCE.getString(DriverResource.DETECTED_ZIP_COMMENT), zipc));
             if (zipc.indexOf(Utils.PACK_ZIP_ARCHIVE_MARKER_COMMENT) >= 0) {
                     System.out.println(MessageFormat.format(RESOURCE.getString(DriverResource.SKIP_FOR_REPACKED), jarfile));
@@ -552,7 +552,7 @@
             if (words.length == 0)    continue loadOptmap;
             String opt = words[0];
             words[0] = "";  // initial word is not a spec
-            if (opt.length() == 0 && words.length >= 1) {
+            if (opt.isEmpty() && words.length >= 1) {
                 opt = words[1];  // initial "word" is empty due to leading ' '
                 words[1] = "";
             }
@@ -622,7 +622,7 @@
                     switch (specop) {
                     case '+':
                         // + means we want an non-empty val suffix.
-                        ok = (val.length() != 0);
+                        ok = !val.isEmpty();
                         specop = spec.charAt(sidx++);
                         break;
                     case '*':
@@ -641,10 +641,10 @@
                     String specarg = spec.substring(sidx);
                     switch (specop) {
                     case '.':  // terminate the option sequence
-                        resultString = (specarg.length() != 0)? specarg.intern(): opt;
+                        resultString = specarg.isEmpty() ? opt : specarg.intern();
                         break doArgs;
                     case '?':  // abort the option sequence
-                        resultString = (specarg.length() != 0)? specarg.intern(): arg;
+                        resultString = specarg.isEmpty() ? arg : specarg.intern();
                         isError = true;
                         break eachSpec;
                     case '@':  // change the effective opt name
@@ -655,14 +655,14 @@
                         val = "";
                         break;
                     case '!':  // negation option
-                        String negopt = (specarg.length() != 0)? specarg.intern(): opt;
+                        String negopt = specarg.isEmpty() ? opt : specarg.intern();
                         properties.remove(negopt);
                         properties.put(negopt, null);  // leave placeholder
                         didAction = true;
                         break;
                     case '$':  // normal "boolean" option
                         String boolval;
-                        if (specarg.length() != 0) {
+                        if (!specarg.isEmpty()) {
                             // If there is a given spec token, store it.
                             boolval = specarg;
                         } else {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/com/sun/net/ssl/KeyManagerFactory.java
--- a/src/java.base/share/classes/com/sun/net/ssl/KeyManagerFactory.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/com/sun/net/ssl/KeyManagerFactory.java	Thu Dec 13 11:51:06 2018 -0800
@@ -153,7 +153,7 @@
                                                  String provider)
         throws NoSuchAlgorithmException, NoSuchProviderException
     {
-        if (provider == null || provider.length() == 0)
+        if (provider == null || provider.isEmpty())
             throw new IllegalArgumentException("missing provider");
         Object[] objs = SSLSecurity.getImpl(algorithm, "KeyManagerFactory",
                                             provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/com/sun/net/ssl/SSLContext.java
--- a/src/java.base/share/classes/com/sun/net/ssl/SSLContext.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/com/sun/net/ssl/SSLContext.java	Thu Dec 13 11:51:06 2018 -0800
@@ -109,7 +109,7 @@
     public static SSLContext getInstance(String protocol, String provider)
         throws NoSuchAlgorithmException, NoSuchProviderException
     {
-        if (provider == null || provider.length() == 0)
+        if (provider == null || provider.isEmpty())
             throw new IllegalArgumentException("missing provider");
         Object[] objs = SSLSecurity.getImpl(protocol, "SSLContext",
                                             provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/com/sun/net/ssl/TrustManagerFactory.java
--- a/src/java.base/share/classes/com/sun/net/ssl/TrustManagerFactory.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/com/sun/net/ssl/TrustManagerFactory.java	Thu Dec 13 11:51:06 2018 -0800
@@ -155,7 +155,7 @@
                                                  String provider)
         throws NoSuchAlgorithmException, NoSuchProviderException
     {
-        if (provider == null || provider.length() == 0)
+        if (provider == null || provider.isEmpty())
             throw new IllegalArgumentException("missing provider");
         Object[] objs = SSLSecurity.getImpl(algorithm, "TrustManagerFactory",
                                             provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/io/Console.java
--- a/src/java.base/share/classes/java/io/Console.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/io/Console.java	Thu Dec 13 11:51:06 2018 -0800
@@ -247,7 +247,7 @@
         String line = null;
         synchronized (writeLock) {
             synchronized(readLock) {
-                if (fmt.length() != 0)
+                if (!fmt.isEmpty())
                     pw.format(fmt, args);
                 try {
                     char[] ca = readline(false);
@@ -319,7 +319,7 @@
                 }
                 IOError ioe = null;
                 try {
-                    if (fmt.length() != 0)
+                    if (!fmt.isEmpty())
                         pw.format(fmt, args);
                     passwd = readline(true);
                 } catch (IOException x) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/ClassLoader.java
--- a/src/java.base/share/classes/java/lang/ClassLoader.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/ClassLoader.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1119,7 +1119,7 @@
 
     // true if the name is null or has the potential to be a valid binary name
     private boolean checkName(String name) {
-        if ((name == null) || (name.length() == 0))
+        if ((name == null) || (name.isEmpty()))
             return true;
         if ((name.indexOf('/') != -1) || (name.charAt(0) == '['))
             return false;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/Double.java
--- a/src/java.base/share/classes/java/lang/Double.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/Double.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1077,8 +1077,8 @@
     }
 
     /**
-     * Returns a nominal descriptor for this instance, which is the instance
-     * itself.
+     * Returns an {@link Optional} containing the nominal descriptor for this
+     * instance, which is the instance itself.
      *
      * @return an {@link Optional} describing the {@linkplain Double} instance
      * @since 12
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/Float.java
--- a/src/java.base/share/classes/java/lang/Float.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/Float.java	Thu Dec 13 11:51:06 2018 -0800
@@ -989,8 +989,8 @@
     }
 
     /**
-     * Returns a nominal descriptor for this instance, which is the instance
-     * itself.
+     * Returns an {@link Optional} containing the nominal descriptor for this
+     * instance, which is the instance itself.
      *
      * @return an {@link Optional} describing the {@linkplain Float} instance
      * @since 12
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/Integer.java
--- a/src/java.base/share/classes/java/lang/Integer.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/Integer.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1409,7 +1409,7 @@
         boolean negative = false;
         Integer result;
 
-        if (nm.length() == 0)
+        if (nm.isEmpty())
             throw new NumberFormatException("Zero length string");
         char firstChar = nm.charAt(0);
         // Handle sign, if present
@@ -1838,8 +1838,8 @@
     }
 
     /**
-     * Returns a nominal descriptor for this instance, which is the instance
-     * itself.
+     * Returns an {@link Optional} containing the nominal descriptor for this
+     * instance, which is the instance itself.
      *
      * @return an {@link Optional} describing the {@linkplain Integer} instance
      * @since 12
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/Long.java
--- a/src/java.base/share/classes/java/lang/Long.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/Long.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1248,7 +1248,7 @@
         boolean negative = false;
         Long result;
 
-        if (nm.length() == 0)
+        if (nm.isEmpty())
             throw new NumberFormatException("Zero length string");
         char firstChar = nm.charAt(0);
         // Handle sign, if present
@@ -1967,8 +1967,8 @@
     }
 
     /**
-     * Returns a nominal descriptor for this instance, which is the instance
-     * itself.
+     * Returns an {@link Optional} containing the nominal descriptor for this
+     * instance, which is the instance itself.
      *
      * @return an {@link Optional} describing the {@linkplain Long} instance
      * @since 12
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/Package.java
--- a/src/java.base/share/classes/java/lang/Package.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/Package.java	Thu Dec 13 11:51:06 2018 -0800
@@ -397,11 +397,11 @@
     public String toString() {
         String spec = versionInfo.specTitle;
         String ver =  versionInfo.specVersion;
-        if (spec != null && spec.length() > 0)
+        if (spec != null && !spec.isEmpty())
             spec = ", " + spec;
         else
             spec = "";
-        if (ver != null && ver.length() > 0)
+        if (ver != null && !ver.isEmpty())
             ver = ", version " + ver;
         else
             ver = "";
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/Runtime.java
--- a/src/java.base/share/classes/java/lang/Runtime.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/Runtime.java	Thu Dec 13 11:51:06 2018 -0800
@@ -403,7 +403,7 @@
      */
     public Process exec(String command, String[] envp, File dir)
         throws IOException {
-        if (command.length() == 0)
+        if (command.isEmpty())
             throw new IllegalArgumentException("Empty command");
 
         StringTokenizer st = new StringTokenizer(command);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/String.java
--- a/src/java.base/share/classes/java/lang/String.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/String.java	Thu Dec 13 11:51:06 2018 -0800
@@ -664,7 +664,7 @@
      *          object.
      */
     public int length() {
-        return value.length >> coder();
+        return isLatin1() ? value.length : value.length >> UTF16;
     }
 
     /**
@@ -1943,8 +1943,7 @@
      *          characters followed by the string argument's characters.
      */
     public String concat(String str) {
-        int olen = str.length();
-        if (olen == 0) {
+        if (str.isEmpty()) {
             return this;
         }
         if (coder() == str.coder()) {
@@ -1956,6 +1955,7 @@
             return new String(buf, coder);
         }
         int len = length();
+        int olen = str.length();
         byte[] buf = StringUTF16.newBytesFor(len + olen);
         getBytes(buf, 0, UTF16);
         str.getBytes(buf, len, UTF16);
@@ -2316,7 +2316,7 @@
             // Construct result
             int resultSize = list.size();
             if (limit == 0) {
-                while (resultSize > 0 && list.get(resultSize - 1).length() == 0) {
+                while (resultSize > 0 && list.get(resultSize - 1).isEmpty()) {
                     resultSize--;
                 }
             }
@@ -3545,8 +3545,8 @@
     }
 
     /**
-     * Returns a nominal descriptor for this instance, which is the instance
-     * itself.
+     * Returns an {@link Optional} containing the nominal descriptor for this
+     * instance, which is the instance itself.
      *
      * @return an {@link Optional} describing the {@linkplain String} instance
      * @since 12
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/VersionProps.java.template
--- a/src/java.base/share/classes/java/lang/VersionProps.java.template	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/VersionProps.java.template	Thu Dec 13 11:51:06 2018 -0800
@@ -73,7 +73,7 @@
         "@@VENDOR_VERSION_STRING@@";
 
     private static final String vendor_version =
-        (VENDOR_VERSION_STRING.length() > 0
+        (!VENDOR_VERSION_STRING.isEmpty()
          ? " " + VENDOR_VERSION_STRING : "");
 
     private static final String VENDOR =
@@ -95,7 +95,7 @@
         props.put("java.version.date", java_version_date);
         props.put("java.runtime.version", java_runtime_version);
         props.put("java.runtime.name", java_runtime_name);
-        if (VENDOR_VERSION_STRING.length() > 0)
+        if (!VENDOR_VERSION_STRING.isEmpty())
             props.put("java.vendor.version", VENDOR_VERSION_STRING);
 
         props.put("java.class.version", CLASSFILE_MAJOR_MINOR);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/constant/ClassDesc.java
--- a/src/java.base/share/classes/java/lang/constant/ClassDesc.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/constant/ClassDesc.java	Thu Dec 13 11:51:06 2018 -0800
@@ -112,13 +112,13 @@
      *
      * A field type descriptor string for a non-array type is either
      * a one-letter code corresponding to a primitive type
-     * ({@code J,I,C,S,B,D,F,Z,V}), or the letter {@code L}, followed
-     * by the fully qualified binary name of a class, followed by {@code ;}.
-     * A field type descriptor for an array type is the character {@code [}
+     * ({@code "J", "I", "C", "S", "B", "D", "F", "Z", "V"}), or the letter {@code "L"}, followed
+     * by the fully qualified binary name of a class, followed by {@code ";"}.
+     * A field type descriptor for an array type is the character {@code "["}
      * followed by the field descriptor for the component type.  Examples of
-     * valid type descriptor strings include {@code Ljava/lang/String;}, {@code I},
-     * {@code [I}, {@code V}, {@code [Ljava/lang/String;}, etc.
-     * for more detail.
+     * valid type descriptor strings include {@code "Ljava/lang/String;"}, {@code "I"},
+     * {@code "[I"}, {@code "V"}, {@code "[Ljava/lang/String;"}, etc.
+     * See JVMS 4.3.2 ("Field Descriptors") for more detail.
      *
      * @param descriptor a field descriptor string
      * @return a {@linkplain ClassDesc} describing the desired class
@@ -126,9 +126,15 @@
      * @throws IllegalArgumentException if the name string is not in the
      * correct format
      * @jvms 4.3.2 Field Descriptors
+     * @jvms 4.4.1 The CONSTANT_Class_info Structure
      */
     static ClassDesc ofDescriptor(String descriptor) {
         requireNonNull(descriptor);
+        int depth = ConstantUtils.arrayDepth(descriptor);
+        if (depth > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
+            throw new IllegalArgumentException(String.format("Cannot create an array type descriptor with more than %d dimensions",
+                    ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS));
+        }
         return (descriptor.length() == 1)
                ? new PrimitiveClassDescImpl(descriptor)
                : new ReferenceClassDescImpl(descriptor);
@@ -139,8 +145,15 @@
      * is described by this {@linkplain ClassDesc}.
      *
      * @return a {@linkplain ClassDesc} describing the array type
+     * @throws IllegalStateException if the resulting {@linkplain ClassDesc} would have an array rank of greater than 255
+     * @jvms 4.4.1 The CONSTANT_Class_info Structure
      */
     default ClassDesc arrayType() {
+        int depth = ConstantUtils.arrayDepth(descriptorString());
+        if (depth >= ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
+            throw new IllegalStateException(String.format("Cannot create an array type descriptor with more than %d dimensions",
+                    ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS));
+        }
         return arrayType(1);
     }
 
@@ -150,11 +163,14 @@
      *
      * @param rank the rank of the array
      * @return a {@linkplain ClassDesc} describing the array type
-     * @throws IllegalArgumentException if the rank is zero or negative
+     * @throws IllegalArgumentException if the rank is less than zero or if the rank of the resulting array type is
+     * greater than 255
+     * @jvms 4.4.1 The CONSTANT_Class_info Structure
      */
     default ClassDesc arrayType(int rank) {
-        if (rank <= 0)
-            throw new IllegalArgumentException("rank: " + rank);
+        int currentDepth = ConstantUtils.arrayDepth(descriptorString());
+        if (rank <= 0 || currentDepth + rank > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS)
+            throw new IllegalArgumentException("rank: " + currentDepth + rank);
         return ClassDesc.ofDescriptor("[".repeat(rank) + descriptorString());
     }
 
@@ -162,6 +178,12 @@
      * Returns a {@linkplain ClassDesc} for a nested class of the class or
      * interface type described by this {@linkplain ClassDesc}.
      *
+     * @apiNote
+     *
+     * Example: If descriptor {@code d} describes the class {@code java.util.Map}, a
+     * descriptor for the class {@code java.util.Map.Entry} could be obtained
+     * by {@code d.nested("Entry")}.
+     *
      * @param nestedName the unqualified name of the nested class
      * @return a {@linkplain ClassDesc} describing the nested class
      * @throws NullPointerException if any argument is {@code null}
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/constant/Constable.java
--- a/src/java.base/share/classes/java/lang/constant/Constable.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/constant/Constable.java	Thu Dec 13 11:51:06 2018 -0800
@@ -65,8 +65,9 @@
  */
 public interface Constable {
     /**
-     * Returns a nominal descriptor for this instance, if one can be
-     * constructed, or an empty {@link Optional} if one cannot be constructed.
+     * Returns an {@link Optional} containing the nominal descriptor for this
+     * instance, if one can be constructed, or an empty {@link Optional}
+     * if one cannot be constructed.
      *
      * @return An {@link Optional} containing the resulting nominal descriptor,
      * or an empty {@link Optional} if one cannot be constructed.
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/constant/ConstantUtils.java
--- a/src/java.base/share/classes/java/lang/constant/ConstantUtils.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/constant/ConstantUtils.java	Thu Dec 13 11:51:06 2018 -0800
@@ -37,6 +37,7 @@
     /** an empty constant descriptor */
     public static final ConstantDesc[] EMPTY_CONSTANTDESC = new ConstantDesc[0];
     static final Constable[] EMPTY_CONSTABLE = new Constable[0];
+    static final int MAX_ARRAY_TYPE_DESC_DIMENSIONS = 255;
 
     private static final Set<String> pointyNames = Set.of("<init>", "<clinit>");
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/constant/package-info.java
--- a/src/java.base/share/classes/java/lang/constant/package-info.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/constant/package-info.java	Thu Dec 13 11:51:06 2018 -0800
@@ -49,7 +49,7 @@
  * storing the value in a constant pool entry, or reconstituting the value given
  * a class loading context.  Every {@link java.lang.constant.ConstantDesc}
  * knows how to <em>resolve</em> itself -- compute the value that it describes --
- * via {@link java.lang.constant.ConstantDesc#resolveConstantDesc(java.lang.invoke.MethodHandles.Lookup)}.
+ * via {@link java.lang.constant.ConstantDesc#resolveConstantDesc(java.lang.invoke.MethodHandles.Lookup) ConstantDesc.resolveConstantDesc}.
  * This allows an API which accepts {@link java.lang.constant.ConstantDesc}
  * objects to evaluate them reflectively, provided that the classes and methods
  * referenced in their nominal description are present and accessible.
@@ -68,7 +68,7 @@
  * When a bytecode-reading API encounters a constant pool entry, it can
  * convert it to the appropriate type of nominal descriptor.  For dynamic
  * constants, bytecode-reading APIs may wish to use the factory
- * {@link java.lang.constant.DynamicConstantDesc#ofCanonical(DirectMethodHandleDesc, java.lang.String, ClassDesc, ConstantDesc[])},
+ * {@link java.lang.constant.DynamicConstantDesc#ofCanonical(DirectMethodHandleDesc, java.lang.String, ClassDesc, ConstantDesc[]) DynamicConstantDesc.ofCanonical},
  * which will inspect the bootstrap and, for well-known bootstraps, return
  * a more specific subtype of {@link java.lang.constant.DynamicConstantDesc}, such as
  * {@link java.lang.Enum.EnumDesc}.
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/invoke/ConstantBootstraps.java
--- a/src/java.base/share/classes/java/lang/invoke/ConstantBootstraps.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/invoke/ConstantBootstraps.java	Thu Dec 13 11:51:06 2018 -0800
@@ -103,7 +103,7 @@
         if (type != Class.class) {
             throw new IllegalArgumentException();
         }
-        if (name.length() == 0 || name.length() > 1) {
+        if (name.length() != 1) {
             throw new IllegalArgumentException(String.format("not primitive: %s", name));
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/invoke/MethodHandles.java
--- a/src/java.base/share/classes/java/lang/invoke/MethodHandles.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/invoke/MethodHandles.java	Thu Dec 13 11:51:06 2018 -0800
@@ -201,7 +201,7 @@
             throw new IllegalAccessException(callerModule + " does not read " + targetModule);
         if (targetModule.isNamed()) {
             String pn = targetClass.getPackageName();
-            assert pn.length() > 0 : "unnamed package cannot be in named module";
+            assert !pn.isEmpty() : "unnamed package cannot be in named module";
             if (!targetModule.isOpen(pn, callerModule))
                 throw new IllegalAccessException(targetModule + " does not open " + pn + " to " + callerModule);
         }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/invoke/ProxyClassesDumper.java
--- a/src/java.base/share/classes/java/lang/invoke/ProxyClassesDumper.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/invoke/ProxyClassesDumper.java	Thu Dec 13 11:51:06 2018 -0800
@@ -62,7 +62,7 @@
         }
         try {
             path = path.trim();
-            final Path dir = Path.of(path.length() == 0 ? "." : path);
+            final Path dir = Path.of(path.isEmpty() ? "." : path);
             AccessController.doPrivileged(new PrivilegedAction<>() {
                     @Override
                     public Void run() {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/invoke/TypeDescriptor.java
--- a/src/java.base/share/classes/java/lang/invoke/TypeDescriptor.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/invoke/TypeDescriptor.java	Thu Dec 13 11:51:06 2018 -0800
@@ -61,7 +61,8 @@
         boolean isArray();
 
         /**
-         * Does this field descriptor describe a primitive type?
+         * Does this field descriptor describe a primitive type (including void.)
+         *
          * @return whether this field descriptor describes a primitive type
          */
         boolean isPrimitive();
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/lang/invoke/VarHandle.java
--- a/src/java.base/share/classes/java/lang/invoke/VarHandle.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/lang/invoke/VarHandle.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1864,6 +1864,16 @@
         }
     }
 
+    /**
+     * Compare this {@linkplain VarHandle} with another object for equality.
+     * Two {@linkplain VarHandle}s are considered equal if they both describe the
+     * same instance field, both describe the same static field, both describe
+     * array elements for arrays with the same component type, or both describe
+     * the same component of an off-heap structure.
+     *
+     * @param o the other object
+     * @return Whether this {@linkplain VarHandle} is equal to the other object
+     */
     @Override
     public final boolean equals(Object o) {
         if (this == o) return true;
@@ -1883,6 +1893,12 @@
 
     abstract int internalHashCode();
 
+    /**
+     * Returns a compact textual description of this {@linkplain VarHandle},
+     * including the type of variable described, and a description of its coordinates.
+     *
+     * @return A compact textual description of this {@linkplain VarHandle}
+     */
     @Override
     public final String toString() {
         return String.format("VarHandle[varType=%s, coord=%s]",
@@ -2272,6 +2288,14 @@
             }
         }
 
+        /**
+         * Returns a compact textual description of this constant description.
+         * For a field {@linkplain VarHandle}, includes the owner, name, and type
+         * of the field, and whether it is static; for an array {@linkplain VarHandle},
+         * the name of the component type.
+         *
+         * @return A compact textual description of this descriptor
+         */
         @Override
         public String toString() {
             switch (kind) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/HttpCookie.java
--- a/src/java.base/share/classes/java/net/HttpCookie.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/HttpCookie.java	Thu Dec 13 11:51:06 2018 -0800
@@ -149,7 +149,7 @@
      */
     HttpCookie(String name, String value, String header, long creationTime) {
         name = name.trim();
-        if (name.length() == 0 || !isToken(name) || name.charAt(0) == '$') {
+        if (name.isEmpty() || !isToken(name) || name.charAt(0) == '$') {
             throw new IllegalArgumentException("Illegal cookie name");
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/Inet6Address.java
--- a/src/java.base/share/classes/java/net/Inet6Address.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/Inet6Address.java	Thu Dec 13 11:51:06 2018 -0800
@@ -433,7 +433,7 @@
                                             NetworkInterface nif)
         throws UnknownHostException
     {
-        if (host != null && host.length() > 0 && host.charAt(0) == '[') {
+        if (host != null && !host.isEmpty() && host.charAt(0) == '[') {
             if (host.charAt(host.length()-1) == ']') {
                 host = host.substring(1, host.length() -1);
             }
@@ -466,7 +466,7 @@
                                             int scope_id)
         throws UnknownHostException
     {
-        if (host != null && host.length() > 0 && host.charAt(0) == '[') {
+        if (host != null && !host.isEmpty() && host.charAt(0) == '[') {
             if (host.charAt(host.length()-1) == ']') {
                 host = host.substring(1, host.length() -1);
             }
@@ -601,7 +601,7 @@
         boolean scope_ifname_set = gf.get("scope_ifname_set", false);
         String ifname = (String)gf.get("ifname", null);
 
-        if (ifname != null && !"".equals (ifname)) {
+        if (ifname != null && !ifname.isEmpty()) {
             try {
                 scope_ifname = NetworkInterface.getByName(ifname);
                 if (scope_ifname == null) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/InetAddress.java
--- a/src/java.base/share/classes/java/net/InetAddress.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/InetAddress.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1187,7 +1187,7 @@
      */
     public static InetAddress getByAddress(String host, byte[] addr)
         throws UnknownHostException {
-        if (host != null && host.length() > 0 && host.charAt(0) == '[') {
+        if (host != null && !host.isEmpty() && host.charAt(0) == '[') {
             if (host.charAt(host.length()-1) == ']') {
                 host = host.substring(1, host.length() -1);
             }
@@ -1301,7 +1301,7 @@
     private static InetAddress[] getAllByName(String host, InetAddress reqAddr)
         throws UnknownHostException {
 
-        if (host == null || host.length() == 0) {
+        if (host == null || host.isEmpty()) {
             InetAddress[] ret = new InetAddress[1];
             ret[0] = impl.loopbackAddress();
             return ret;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/SocketPermission.java
--- a/src/java.base/share/classes/java/net/SocketPermission.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/SocketPermission.java	Thu Dec 13 11:51:06 2018 -0800
@@ -460,7 +460,7 @@
             }
             return;
         } else {
-            if (host.length() > 0) {
+            if (!host.isEmpty()) {
                 // see if we are being initialized with an IP address.
                 char ch = host.charAt(0);
                 if (ch == ':' || Character.digit(ch, 16) != -1) {
@@ -705,8 +705,7 @@
                                       .orElse(b);
         }
 
-        return cdomain.length() != 0 && hdomain.length() != 0
-                        && cdomain.equals(hdomain);
+        return !cdomain.isEmpty() && !hdomain.isEmpty() && cdomain.equals(hdomain);
     }
 
     private boolean authorized(String cname, byte[] addr) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/URI.java
--- a/src/java.base/share/classes/java/net/URI.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/URI.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1959,10 +1959,8 @@
         throws URISyntaxException
     {
         if (scheme != null) {
-            if ((path != null)
-                && ((path.length() > 0) && (path.charAt(0) != '/')))
-                throw new URISyntaxException(s,
-                                             "Relative path in absolute URI");
+            if (path != null && !path.isEmpty() && path.charAt(0) != '/')
+                throw new URISyntaxException(s, "Relative path in absolute URI");
         }
     }
 
@@ -2163,7 +2161,7 @@
             ru.port = base.port;
 
             String cp = (child.path == null) ? "" : child.path;
-            if ((cp.length() > 0) && (cp.charAt(0) == '/')) {
+            if (!cp.isEmpty() && cp.charAt(0) == '/') {
                 // 5.2 (5): Child path is absolute
                 ru.path = child.path;
             } else {
@@ -2187,7 +2185,7 @@
     // o.w., return a new URI containing the normalized path.
     //
     private static URI normalize(URI u) {
-        if (u.isOpaque() || (u.path == null) || (u.path.length() == 0))
+        if (u.isOpaque() || u.path == null || u.path.isEmpty())
             return u;
 
         String np = normalize(u.path);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/URL.java
--- a/src/java.base/share/classes/java/net/URL.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/URL.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1513,7 +1513,7 @@
         String ref = (String)gf.get("ref", null);
         int hashCode = gf.get("hashCode", -1);
         if (authority == null
-                && ((host != null && host.length() > 0) || port != -1)) {
+                && ((host != null && !host.isEmpty()) || port != -1)) {
             if (host == null)
                 host = "";
             authority = (port == -1) ? host : host + ":" + port;
@@ -1560,7 +1560,7 @@
 
         // Construct authority part
         if (authority == null
-            && ((host != null && host.length() > 0) || port != -1)) {
+            && ((host != null && !host.isEmpty()) || port != -1)) {
             if (host == null)
                 host = "";
             authority = (port == -1) ? host : host + ":" + port;
@@ -1716,7 +1716,7 @@
 
         // pre-compute length of StringBuffer
         int len = protocol.length() + 1;
-        if (authority != null && authority.length() > 0)
+        if (authority != null && !authority.isEmpty())
             len += 2 + authority.length();
         if (file != null) {
             len += file.length();
@@ -1726,7 +1726,7 @@
         StringBuilder result = new StringBuilder(len);
         result.append(protocol);
         result.append(":");
-        if (authority != null && authority.length() > 0) {
+        if (authority != null && !authority.isEmpty()) {
             result.append("//");
             result.append(authority);
         }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/URLClassLoader.java
--- a/src/java.base/share/classes/java/net/URLClassLoader.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/URLClassLoader.java	Thu Dec 13 11:51:06 2018 -0800
@@ -743,7 +743,7 @@
                 locUrl = ((JarURLConnection)urlConnection).getJarFileURL();
             }
             String host = locUrl.getHost();
-            if (host != null && (host.length() > 0))
+            if (host != null && !host.isEmpty())
                 p = new SocketPermission(host,
                                          SecurityConstants.SOCKET_CONNECT_ACCEPT_ACTION);
         }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/URLDecoder.java
--- a/src/java.base/share/classes/java/net/URLDecoder.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/URLDecoder.java	Thu Dec 13 11:51:06 2018 -0800
@@ -133,7 +133,7 @@
      * @since 1.4
      */
     public static String decode(String s, String enc) throws UnsupportedEncodingException {
-        if (enc.length() == 0) {
+        if (enc.isEmpty()) {
             throw new UnsupportedEncodingException ("URLDecoder: empty string enc parameter");
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/URLPermission.java
--- a/src/java.base/share/classes/java/net/URLPermission.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/URLPermission.java	Thu Dec 13 11:51:06 2018 -0800
@@ -409,7 +409,7 @@
             char c = methods.charAt(i);
             if (c == ',') {
                 String s = b.toString();
-                if (s.length() > 0)
+                if (!s.isEmpty())
                     l.add(s);
                 b = new StringBuilder();
             } else if (c == ' ' || c == '\t') {
@@ -423,7 +423,7 @@
             }
         }
         String s = b.toString();
-        if (s.length() > 0)
+        if (!s.isEmpty())
             l.add(s);
         return l;
     }
@@ -448,7 +448,7 @@
                 b.append(c);
             } else if (c == ',') {
                 String s = b.toString();
-                if (s.length() > 0)
+                if (!s.isEmpty())
                     l.add(s);
                 b = new StringBuilder();
                 capitalizeNext = true;
@@ -458,7 +458,7 @@
             }
         }
         String s = b.toString();
-        if (s.length() > 0)
+        if (!s.isEmpty())
             l.add(s);
         return l;
     }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/net/URLStreamHandler.java
--- a/src/java.base/share/classes/java/net/URLStreamHandler.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/net/URLStreamHandler.java	Thu Dec 13 11:51:06 2018 -0800
@@ -235,7 +235,7 @@
             start = i;
             // If the authority is defined then the path is defined by the
             // spec only; See RFC 2396 Section 5.2.4.
-            if (authority != null && authority.length() > 0)
+            if (authority != null && !authority.isEmpty())
                 path = "";
         }
 
@@ -247,7 +247,7 @@
         if (start < limit) {
             if (spec.charAt(start) == '/') {
                 path = spec.substring(start, limit);
-            } else if (path != null && path.length() > 0) {
+            } else if (path != null && !path.isEmpty()) {
                 isRelPath = true;
                 int ind = path.lastIndexOf('/');
                 String separator = "";
@@ -483,11 +483,11 @@
         String s;
         return u.getProtocol()
             + ':'
-            + (((s = u.getAuthority()) != null && s.length() > 0)
+            + ((s = u.getAuthority()) != null && !s.isEmpty()
                ? "//" + s : "")
-            + (((s = u.getPath()) != null) ? s : "")
-            + (((s = u.getQuery()) != null) ? '?' + s : "")
-            + (((s = u.getRef()) != null) ? '#' + s : "");
+            + ((s = u.getPath()) != null ? s : "")
+            + ((s = u.getQuery()) != null ? '?' + s : "")
+            + ((s = u.getRef()) != null ? '#' + s : "");
     }
 
     /**
@@ -544,7 +544,7 @@
          */
         String authority = null;
         String userInfo = null;
-        if (host != null && host.length() != 0) {
+        if (host != null && !host.isEmpty()) {
             authority = (port == -1) ? host : host + ":" + port;
             int at = host.lastIndexOf('@');
             if (at != -1) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/nio/file/LinkPermission.java
--- a/src/java.base/share/classes/java/nio/file/LinkPermission.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/nio/file/LinkPermission.java	Thu Dec 13 11:51:06 2018 -0800
@@ -104,7 +104,7 @@
     public LinkPermission(String name, String actions) {
         super(name);
         checkName(name);
-        if (actions != null && actions.length() > 0) {
+        if (actions != null && !actions.isEmpty()) {
             throw new IllegalArgumentException("actions: " + actions);
         }
     }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/AlgorithmParameterGenerator.java
--- a/src/java.base/share/classes/java/security/AlgorithmParameterGenerator.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/AlgorithmParameterGenerator.java	Thu Dec 13 11:51:06 2018 -0800
@@ -228,7 +228,7 @@
         throws NoSuchAlgorithmException, NoSuchProviderException
     {
         Objects.requireNonNull(algorithm, "null algorithm name");
-        if (provider == null || provider.length() == 0)
+        if (provider == null || provider.isEmpty())
             throw new IllegalArgumentException("missing provider");
         Object[] objs = Security.getImpl(algorithm,
                                          "AlgorithmParameterGenerator",
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/AlgorithmParameters.java
--- a/src/java.base/share/classes/java/security/AlgorithmParameters.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/AlgorithmParameters.java	Thu Dec 13 11:51:06 2018 -0800
@@ -209,7 +209,7 @@
         throws NoSuchAlgorithmException, NoSuchProviderException
     {
         Objects.requireNonNull(algorithm, "null algorithm name");
-        if (provider == null || provider.length() == 0)
+        if (provider == null || provider.isEmpty())
             throw new IllegalArgumentException("missing provider");
         Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
                                          provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/KeyStore.java
--- a/src/java.base/share/classes/java/security/KeyStore.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/KeyStore.java	Thu Dec 13 11:51:06 2018 -0800
@@ -913,7 +913,7 @@
         throws KeyStoreException, NoSuchProviderException
     {
         Objects.requireNonNull(type, "null type name");
-        if (provider == null || provider.length() == 0)
+        if (provider == null || provider.isEmpty())
             throw new IllegalArgumentException("missing provider");
         try {
             Object[] objs = Security.getImpl(type, "KeyStore", provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/MessageDigest.java
--- a/src/java.base/share/classes/java/security/MessageDigest.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/MessageDigest.java	Thu Dec 13 11:51:06 2018 -0800
@@ -237,7 +237,7 @@
         throws NoSuchAlgorithmException, NoSuchProviderException
     {
         Objects.requireNonNull(algorithm, "null algorithm name");
-        if (provider == null || provider.length() == 0)
+        if (provider == null || provider.isEmpty())
             throw new IllegalArgumentException("missing provider");
         Object[] objs = Security.getImpl(algorithm, "MessageDigest", provider);
         if (objs[0] instanceof MessageDigest) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/Permission.java
--- a/src/java.base/share/classes/java/security/Permission.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/Permission.java	Thu Dec 13 11:51:06 2018 -0800
@@ -222,7 +222,7 @@
      */
     public String toString() {
         String actions = getActions();
-        if ((actions == null) || (actions.length() == 0)) { // OPTIONAL
+        if (actions == null || actions.isEmpty()) { // OPTIONAL
             return "(\"" + getClass().getName() + "\" \"" + name + "\")";
         } else {
             return "(\"" + getClass().getName() + "\" \"" + name +
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/Policy.java
--- a/src/java.base/share/classes/java/security/Policy.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/Policy.java	Thu Dec 13 11:51:06 2018 -0800
@@ -456,7 +456,7 @@
                 throws NoSuchProviderException, NoSuchAlgorithmException {
 
         Objects.requireNonNull(type, "null type name");
-        if (provider == null || provider.length() == 0) {
+        if (provider == null || provider.isEmpty()) {
             throw new IllegalArgumentException("missing provider");
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/SecureRandom.java
--- a/src/java.base/share/classes/java/security/SecureRandom.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/SecureRandom.java	Thu Dec 13 11:51:06 2018 -0800
@@ -942,7 +942,7 @@
                 }
             });
 
-        if ((property == null) || (property.length() == 0)) {
+        if (property == null || property.isEmpty()) {
             throw new NoSuchAlgorithmException(
                 "Null/empty securerandom.strongAlgorithms Security Property");
         }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/Security.java
--- a/src/java.base/share/classes/java/security/Security.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/Security.java	Thu Dec 13 11:51:06 2018 -0800
@@ -649,7 +649,7 @@
             }
         }
 
-        if ((candidates == null) || (candidates.isEmpty()))
+        if (candidates == null || candidates.isEmpty())
             return null;
 
         Object[] candidatesArray = candidates.toArray();
@@ -1005,11 +1005,11 @@
         String algName = null;
         String attrName = null;
 
-        if (filterValue.length() == 0) {
+        if (filterValue.isEmpty()) {
             // The filterValue is an empty string. So the filterKey
             // should be in the format of <crypto_service>.<algorithm_or_type>.
             algName = filterKey.substring(algIndex + 1).trim();
-            if (algName.length() == 0) {
+            if (algName.isEmpty()) {
                 // There must be a algorithm or type name.
                 throw new InvalidParameterException("Invalid filter");
             }
@@ -1024,7 +1024,7 @@
                 throw new InvalidParameterException("Invalid filter");
             } else {
                 attrName = filterKey.substring(attrIndex + 1).trim();
-                if (attrName.length() == 0) {
+                if (attrName.isEmpty()) {
                     // There is no attribute name in the filter.
                     throw new InvalidParameterException("Invalid filter");
                 }
@@ -1070,7 +1070,7 @@
      **/
     public static Set<String> getAlgorithms(String serviceName) {
 
-        if ((serviceName == null) || (serviceName.length() == 0) ||
+        if ((serviceName == null) || (serviceName.isEmpty()) ||
             (serviceName.endsWith("."))) {
             return Collections.emptySet();
         }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/Signature.java
--- a/src/java.base/share/classes/java/security/Signature.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/Signature.java	Thu Dec 13 11:51:06 2018 -0800
@@ -360,7 +360,7 @@
         Objects.requireNonNull(algorithm, "null algorithm name");
         if (algorithm.equalsIgnoreCase(RSA_SIGNATURE)) {
             // exception compatibility with existing code
-            if ((provider == null) || (provider.length() == 0)) {
+            if (provider == null || provider.isEmpty()) {
                 throw new IllegalArgumentException("missing provider");
             }
             Provider p = Security.getProvider(provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/security/cert/TrustAnchor.java
--- a/src/java.base/share/classes/java/security/cert/TrustAnchor.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/security/cert/TrustAnchor.java	Thu Dec 13 11:51:06 2018 -0800
@@ -210,7 +210,7 @@
         if (caName == null)
             throw new NullPointerException("the caName parameter must be " +
                 "non-null");
-        if (caName.length() == 0)
+        if (caName.isEmpty())
             throw new IllegalArgumentException("the caName " +
                 "parameter must be a non-empty String");
         // check if caName is formatted correctly
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/text/AttributedString.java
--- a/src/java.base/share/classes/java/text/AttributedString.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/text/AttributedString.java	Thu Dec 13 11:51:06 2018 -0800
@@ -85,7 +85,7 @@
 
             text = buffer.toString();
 
-            if (text.length() > 0) {
+            if (!text.isEmpty()) {
                 // Determine the runs, creating a new run when the attributes
                 // differ.
                 int offset = 0;
@@ -144,7 +144,7 @@
         }
         this.text = text;
 
-        if (text.length() == 0) {
+        if (text.isEmpty()) {
             if (attributes.isEmpty())
                 return;
             throw new IllegalArgumentException("Can't add attribute to 0-length text");
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/text/CollationElementIterator.java
--- a/src/java.base/share/classes/java/text/CollationElementIterator.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/text/CollationElementIterator.java	Thu Dec 13 11:51:06 2018 -0800
@@ -125,7 +125,7 @@
     CollationElementIterator(String sourceText, RuleBasedCollator owner) {
         this.owner = owner;
         ordering = owner.getTables();
-        if ( sourceText.length() != 0 ) {
+        if (!sourceText.isEmpty()) {
             NormalizerBase.Mode mode =
                 CollatorUtilities.toNormalizerMode(owner.getDecomposition());
             text = new NormalizerBase(sourceText, mode);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/text/CompactNumberFormat.java
--- a/src/java.base/share/classes/java/text/CompactNumberFormat.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/text/CompactNumberFormat.java	Thu Dec 13 11:51:06 2018 -0800
@@ -799,7 +799,7 @@
      */
     private void append(StringBuffer result, String string,
             FieldDelegate delegate, List<FieldPosition> positions) {
-        if (string.length() > 0) {
+        if (!string.isEmpty()) {
             int start = result.length();
             result.append(string);
             for (int counter = 0; counter < positions.size(); counter++) {
@@ -1213,7 +1213,7 @@
         }
 
         // If no 0s are specified in a non empty pattern, it is invalid
-        if (pattern.length() != 0 && zeros.isEmpty()) {
+        if (!pattern.isEmpty() && zeros.isEmpty()) {
             throw new IllegalArgumentException("Invalid pattern"
                     + " [" + pattern + "]: all patterns must include digit"
                     + " placement 0s");
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/text/DecimalFormat.java
--- a/src/java.base/share/classes/java/text/DecimalFormat.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/text/DecimalFormat.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1113,11 +1113,9 @@
 
             // Records the need for adding prefix or suffix
             fastPathData.positiveAffixesRequired
-                    = (positivePrefix.length() != 0)
-                        || (positiveSuffix.length() != 0);
+                    = !positivePrefix.isEmpty() || !positiveSuffix.isEmpty();
             fastPathData.negativeAffixesRequired
-                    = (negativePrefix.length() != 0)
-                        || (negativeSuffix.length() != 0);
+                    = !negativePrefix.isEmpty() || !negativeSuffix.isEmpty();
 
             // Creates a cached char container for result, with max possible size.
             int maxNbIntegralDigits = 10;
@@ -2062,7 +2060,7 @@
                         Format.Field signAttribute) {
         int start = result.length();
 
-        if (string.length() > 0) {
+        if (!string.isEmpty()) {
             result.append(string);
             for (int counter = 0, max = positions.length; counter < max;
                  counter++) {
@@ -3042,7 +3040,7 @@
                     } else {
                         string = symbols.getCurrencySymbol();
                     }
-                    if (string.length() > 0) {
+                    if (!string.isEmpty()) {
                         if (positions == null) {
                             positions = new ArrayList<>(2);
                         }
@@ -3613,7 +3611,7 @@
             }
         }
 
-        if (pattern.length() == 0) {
+        if (pattern.isEmpty()) {
             posPrefixPattern = posSuffixPattern = "";
             setMinimumIntegerDigits(0);
             setMaximumIntegerDigits(MAXIMUM_INTEGER_DIGITS);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/text/DecimalFormatSymbols.java
--- a/src/java.base/share/classes/java/text/DecimalFormatSymbols.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/text/DecimalFormatSymbols.java	Thu Dec 13 11:51:06 2018 -0800
@@ -663,7 +663,7 @@
         // Check for empty country string separately because it's a valid
         // country ID for Locale (and used for the C locale), but not a valid
         // ISO 3166 country code, and exceptions are expensive.
-        if (locale.getCountry().length() > 0) {
+        if (!locale.getCountry().isEmpty()) {
             try {
                 currency = Currency.getInstance(locale);
             } catch (IllegalArgumentException e) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/text/MergeCollation.java
--- a/src/java.base/share/classes/java/text/MergeCollation.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/text/MergeCollation.java	Thu Dec 13 11:51:06 2018 -0800
@@ -92,7 +92,7 @@
         int i;
         for (i = 0; i < patterns.size(); ++i) {
             PatternEntry entry = patterns.get(i);
-            if (entry.extension.length() != 0) {
+            if (!entry.extension.isEmpty()) {
                 if (extList == null)
                     extList = new ArrayList<>();
                 extList.add(entry);
@@ -122,7 +122,7 @@
     private final PatternEntry findLastWithNoExtension(int i) {
         for (--i;i >= 0; --i) {
             PatternEntry entry = patterns.get(i);
-            if (entry.extension.length() == 0) {
+            if (entry.extension.isEmpty()) {
                 return entry;
             }
         }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/text/MessageFormat.java
--- a/src/java.base/share/classes/java/text/MessageFormat.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/text/MessageFormat.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1330,7 +1330,7 @@
                         }
                         arg = null;
                     }
-                    if (arg != null && arg.length() > 0) {
+                    if (arg != null && !arg.isEmpty()) {
                         result.append(arg);
                         characterIterators.add(
                                  createAttributedCharacterIterator(
@@ -1476,7 +1476,7 @@
 
         // now get the format
         Format newFormat = null;
-        if (segments[SEG_TYPE].length() != 0) {
+        if (!segments[SEG_TYPE].isEmpty()) {
             int type = findKeyword(segments[SEG_TYPE], TYPE_KEYWORDS);
             switch (type) {
             case TYPE_NULL:
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/text/PatternEntry.java
--- a/src/java.base/share/classes/java/text/PatternEntry.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/text/PatternEntry.java	Thu Dec 13 11:51:06 2018 -0800
@@ -141,7 +141,7 @@
         if (showWhiteSpace)
             toAddTo.append(' ');
         appendQuoted(chars,toAddTo);
-        if (showExtension && extension.length() != 0) {
+        if (showExtension && !extension.isEmpty()) {
             toAddTo.append('/');
             appendQuoted(extension,toAddTo);
         }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/text/RBTableBuilder.java
--- a/src/java.base/share/classes/java/text/RBTableBuilder.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/text/RBTableBuilder.java	Thu Dec 13 11:51:06 2018 -0800
@@ -75,13 +75,10 @@
      * @exception ParseException If the rules format is incorrect.
      */
 
-    public void build(String pattern, int decmp) throws ParseException
-    {
-        boolean isSource = true;
-        int i = 0;
+    public void build(String pattern, int decmp) throws ParseException {
         String expChars;
         String groupChars;
-        if (pattern.length() == 0)
+        if (pattern.isEmpty())
             throw new ParseException("Build rules empty.", 0);
 
         // This array maps Unicode characters to their collation ordering
@@ -119,8 +116,7 @@
         int order = 0;
 
         // Now walk though each entry and add it to my own tables
-        for (i = 0; i < mPattern.getCount(); ++i)
-        {
+        for (int i = 0; i < mPattern.getCount(); ++i) {
             PatternEntry entry = mPattern.getItemAt(i);
             if (entry != null) {
                 groupChars = entry.getChars();
@@ -140,7 +136,7 @@
                 order = increment(entry.getStrength(), order);
                 expChars = entry.getExtension();
 
-                if (expChars.length() != 0) {
+                if (!expChars.isEmpty()) {
                     addExpandOrder(groupChars, expChars, order);
                 } else if (groupChars.length() > 1) {
                     char ch = groupChars.charAt(0);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/time/ZoneId.java
--- a/src/java.base/share/classes/java/time/ZoneId.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/time/ZoneId.java	Thu Dec 13 11:51:06 2018 -0800
@@ -372,7 +372,7 @@
     public static ZoneId ofOffset(String prefix, ZoneOffset offset) {
         Objects.requireNonNull(prefix, "prefix");
         Objects.requireNonNull(offset, "offset");
-        if (prefix.length() == 0) {
+        if (prefix.isEmpty()) {
             return offset;
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/time/format/DateTimeFormatterBuilder.java
--- a/src/java.base/share/classes/java/time/format/DateTimeFormatterBuilder.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/time/format/DateTimeFormatterBuilder.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1439,7 +1439,7 @@
      */
     public DateTimeFormatterBuilder appendLiteral(String literal) {
         Objects.requireNonNull(literal, "literal");
-        if (literal.length() > 0) {
+        if (!literal.isEmpty()) {
             if (literal.length() == 1) {
                 appendInternal(new CharLiteralPrinterParser(literal.charAt(0)));
             } else {
@@ -1832,7 +1832,7 @@
                     throw new IllegalArgumentException("Pattern ends with an incomplete string literal: " + pattern);
                 }
                 String str = pattern.substring(start + 1, pos);
-                if (str.length() == 0) {
+                if (str.isEmpty()) {
                     appendLiteral('\'');
                 } else {
                     appendLiteral(str.replace("''", "'"));
@@ -4332,7 +4332,7 @@
             this.key = k;
             this.value = v;
             this.child = child;
-            if (k.length() == 0){
+            if (k.isEmpty()) {
                 c0 = 0xffff;
             } else {
                 c0 = key.charAt(0);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/util/Calendar.java
--- a/src/java.base/share/classes/java/util/Calendar.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/util/Calendar.java	Thu Dec 13 11:51:06 2018 -0800
@@ -2232,7 +2232,7 @@
         if (strings != null) {
             Map<String,Integer> names = new HashMap<>();
             for (int i = 0; i < strings.length; i++) {
-                if (strings[i].length() == 0) {
+                if (strings[i].isEmpty()) {
                     continue;
                 }
                 names.put(strings[i], i);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/util/Locale.java
--- a/src/java.base/share/classes/java/util/Locale.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/util/Locale.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1396,11 +1396,11 @@
      */
     @Override
     public final String toString() {
-        boolean l = (baseLocale.getLanguage().length() != 0);
-        boolean s = (baseLocale.getScript().length() != 0);
-        boolean r = (baseLocale.getRegion().length() != 0);
-        boolean v = (baseLocale.getVariant().length() != 0);
-        boolean e = (localeExtensions != null && localeExtensions.getID().length() != 0);
+        boolean l = !baseLocale.getLanguage().isEmpty();
+        boolean s = !baseLocale.getScript().isEmpty();
+        boolean r = !baseLocale.getRegion().isEmpty();
+        boolean v = !baseLocale.getVariant().isEmpty();
+        boolean e = localeExtensions != null && !localeExtensions.getID().isEmpty();
 
         StringBuilder result = new StringBuilder(baseLocale.getLanguage());
         if (r || (l && (v || s || e))) {
@@ -1504,18 +1504,18 @@
         StringBuilder buf = new StringBuilder();
 
         String subtag = tag.getLanguage();
-        if (subtag.length() > 0) {
+        if (!subtag.isEmpty()) {
             buf.append(LanguageTag.canonicalizeLanguage(subtag));
         }
 
         subtag = tag.getScript();
-        if (subtag.length() > 0) {
+        if (!subtag.isEmpty()) {
             buf.append(LanguageTag.SEP);
             buf.append(LanguageTag.canonicalizeScript(subtag));
         }
 
         subtag = tag.getRegion();
-        if (subtag.length() > 0) {
+        if (!subtag.isEmpty()) {
             buf.append(LanguageTag.SEP);
             buf.append(LanguageTag.canonicalizeRegion(subtag));
         }
@@ -1534,7 +1534,7 @@
         }
 
         subtag = tag.getPrivateuse();
-        if (subtag.length() > 0) {
+        if (!subtag.isEmpty()) {
             if (buf.length() > 0) {
                 buf.append(LanguageTag.SEP);
             }
@@ -1684,7 +1684,7 @@
         bldr.setLanguageTag(tag);
         BaseLocale base = bldr.getBaseLocale();
         LocaleExtensions exts = bldr.getLocaleExtensions();
-        if (exts == null && base.getVariant().length() > 0) {
+        if (exts == null && !base.getVariant().isEmpty()) {
             exts = getCompatibilityExtensions(base.getLanguage(), base.getScript(),
                                               base.getRegion(), base.getVariant());
         }
@@ -1917,7 +1917,7 @@
      * @exception NullPointerException if <code>inLocale</code> is <code>null</code>
      */
     public String getDisplayVariant(Locale inLocale) {
-        if (baseLocale.getVariant().length() == 0)
+        if (baseLocale.getVariant().isEmpty())
             return "";
 
         LocaleResources lr = LocaleProviderAdapter
@@ -1998,14 +1998,14 @@
         // The display name consists of a main name, followed by qualifiers.
         // Typically, the format is "MainName (Qualifier, Qualifier)" but this
         // depends on what pattern is stored in the display locale.
-        String   mainName       = null;
-        String[] qualifierNames = null;
+        String   mainName;
+        String[] qualifierNames;
 
         // The main name is the language, or if there is no language, the script,
         // then if no script, the country. If there is no language/script/country
         // (an anomalous situation) then the display name is simply the variant's
         // display name.
-        if (languageName.length() == 0 && scriptName.length() == 0 && countryName.length() == 0) {
+        if (languageName.isEmpty() && scriptName.isEmpty() && countryName.isEmpty()) {
             if (variantNames.length == 0) {
                 return "";
             } else {
@@ -2013,13 +2013,13 @@
             }
         }
         ArrayList<String> names = new ArrayList<>(4);
-        if (languageName.length() != 0) {
+        if (!languageName.isEmpty()) {
             names.add(languageName);
         }
-        if (scriptName.length() != 0) {
+        if (!scriptName.isEmpty()) {
             names.add(scriptName);
         }
-        if (countryName.length() != 0) {
+        if (!countryName.isEmpty()) {
             names.add(countryName);
         }
         if (variantNames.length != 0) {
@@ -2309,7 +2309,7 @@
         String variant = (String)fields.get("variant", "");
         String extStr = (String)fields.get("extensions", "");
         baseLocale = BaseLocale.getInstance(convertOldISOCodes(language), script, country, variant);
-        if (extStr.length() > 0) {
+        if (!extStr.isEmpty()) {
             try {
                 InternalLocaleBuilder bldr = new InternalLocaleBuilder();
                 bldr.setExtensions(extStr);
@@ -2367,13 +2367,13 @@
         LocaleExtensions extensions = null;
         // Special cases for backward compatibility support
         if (LocaleUtils.caseIgnoreMatch(language, "ja")
-                && script.length() == 0
+                && script.isEmpty()
                 && LocaleUtils.caseIgnoreMatch(country, "jp")
                 && "JP".equals(variant)) {
             // ja_JP_JP -> u-ca-japanese (calendar = japanese)
             extensions = LocaleExtensions.CALENDAR_JAPANESE;
         } else if (LocaleUtils.caseIgnoreMatch(language, "th")
-                && script.length() == 0
+                && script.isEmpty()
                 && LocaleUtils.caseIgnoreMatch(country, "th")
                 && "TH".equals(variant)) {
             // th_TH_TH -> u-nu-thai (numbersystem = thai)
@@ -2806,7 +2806,7 @@
         public Locale build() {
             BaseLocale baseloc = localeBuilder.getBaseLocale();
             LocaleExtensions extensions = localeBuilder.getLocaleExtensions();
-            if (extensions == null && baseloc.getVariant().length() > 0) {
+            if (extensions == null && !baseloc.getVariant().isEmpty()) {
                 extensions = getCompatibilityExtensions(baseloc.getLanguage(), baseloc.getScript(),
                         baseloc.getRegion(), baseloc.getVariant());
             }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/util/ResourceBundle.java
--- a/src/java.base/share/classes/java/util/ResourceBundle.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/util/ResourceBundle.java	Thu Dec 13 11:51:06 2018 -0800
@@ -771,8 +771,8 @@
         @Override
         public String toString() {
             String l = locale.toString();
-            if (l.length() == 0) {
-                if (locale.getVariant().length() != 0) {
+            if (l.isEmpty()) {
+                if (!locale.getVariant().isEmpty()) {
                     l = "__" + locale.getVariant();
                 } else {
                     l = "\"\"";
@@ -2903,7 +2903,7 @@
                     List<Locale> bokmalList = new LinkedList<>();
                     for (Locale l : tmpList) {
                         bokmalList.add(l);
-                        if (l.getLanguage().length() == 0) {
+                        if (l.getLanguage().isEmpty()) {
                             break;
                         }
                         bokmalList.add(Locale.getInstance("no", l.getScript(), l.getCountry(),
@@ -2921,7 +2921,7 @@
                 }
                 // Special handling for Chinese
                 else if (language.equals("zh")) {
-                    if (script.length() == 0 && region.length() > 0) {
+                    if (script.isEmpty() && !region.isEmpty()) {
                         // Supply script for users who want to use zh_Hans/zh_Hant
                         // as bundle names (recommended for Java7+)
                         switch (region) {
@@ -2944,7 +2944,7 @@
             private static List<Locale> getDefaultList(String language, String script, String region, String variant) {
                 List<String> variants = null;
 
-                if (variant.length() > 0) {
+                if (!variant.isEmpty()) {
                     variants = new LinkedList<>();
                     int idx = variant.length();
                     while (idx != -1) {
@@ -2960,14 +2960,14 @@
                         list.add(Locale.getInstance(language, script, region, v, null));
                     }
                 }
-                if (region.length() > 0) {
+                if (!region.isEmpty()) {
                     list.add(Locale.getInstance(language, script, region, "", null));
                 }
-                if (script.length() > 0) {
+                if (!script.isEmpty()) {
                     list.add(Locale.getInstance(language, script, "", "", null));
                     // Special handling for Chinese
                     if (language.equals("zh")) {
-                        if (region.length() == 0) {
+                        if (region.isEmpty()) {
                             // Supply region(country) for users who still package Chinese
                             // bundles using old convension.
                             switch (script) {
@@ -2988,11 +2988,11 @@
                             list.add(Locale.getInstance(language, "", region, v, null));
                         }
                     }
-                    if (region.length() > 0) {
+                    if (!region.isEmpty()) {
                         list.add(Locale.getInstance(language, "", region, "", null));
                     }
                 }
-                if (language.length() > 0) {
+                if (!language.isEmpty()) {
                     list.add(Locale.getInstance(language, "", "", "", null));
                 }
                 // Add root locale at the end
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/util/Scanner.java
--- a/src/java.base/share/classes/java/util/Scanner.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/util/Scanner.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1297,16 +1297,16 @@
         nanString = "\\Q" + dfs.getNaN() + "\\E";
         infinityString = "\\Q" + dfs.getInfinity() + "\\E";
         positivePrefix = df.getPositivePrefix();
-        if (positivePrefix.length() > 0)
+        if (!positivePrefix.isEmpty())
             positivePrefix = "\\Q" + positivePrefix + "\\E";
         negativePrefix = df.getNegativePrefix();
-        if (negativePrefix.length() > 0)
+        if (!negativePrefix.isEmpty())
             negativePrefix = "\\Q" + negativePrefix + "\\E";
         positiveSuffix = df.getPositiveSuffix();
-        if (positiveSuffix.length() > 0)
+        if (!positiveSuffix.isEmpty())
             positiveSuffix = "\\Q" + positiveSuffix + "\\E";
         negativeSuffix = df.getNegativeSuffix();
-        if (negativeSuffix.length() > 0)
+        if (!negativeSuffix.isEmpty())
             negativeSuffix = "\\Q" + negativeSuffix + "\\E";
 
         // Force rebuilding and recompilation of locale dependent
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/java/util/regex/Pattern.java
--- a/src/java.base/share/classes/java/util/regex/Pattern.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/java/util/regex/Pattern.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1390,7 +1390,7 @@
         localTCNCount = 0;
 
         // if length > 0, the Pattern is lazily compiled
-        if (pattern.length() == 0) {
+        if (pattern.isEmpty()) {
             root = new Start(lastAccept);
             matchRoot = lastAccept;
             compiled = true;
@@ -1423,7 +1423,7 @@
         localCount = 0;
         localTCNCount = 0;
 
-        if (pattern.length() > 0) {
+        if (!pattern.isEmpty()) {
             compile();
         } else {
             root = new Start(lastAccept);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/crypto/Cipher.java
--- a/src/java.base/share/classes/javax/crypto/Cipher.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/crypto/Cipher.java	Thu Dec 13 11:51:06 2018 -0800
@@ -341,7 +341,7 @@
             throw new NoSuchAlgorithmException("Invalid transformation " +
                                            "format:" + transformation);
         }
-        if ((parts[0] == null) || (parts[0].length() == 0)) {
+        if ((parts[0] == null) || (parts[0].isEmpty())) {
             throw new NoSuchAlgorithmException("Invalid transformation:" +
                                    "algorithm not specified-"
                                    + transformation);
@@ -445,10 +445,10 @@
         String alg = parts[0];
         String mode = parts[1];
         String pad = parts[2];
-        if ((mode != null) && (mode.length() == 0)) {
+        if ((mode != null) && (mode.isEmpty())) {
             mode = null;
         }
-        if ((pad != null) && (pad.length() == 0)) {
+        if ((pad != null) && (pad.isEmpty())) {
             pad = null;
         }
 
@@ -634,7 +634,7 @@
         if ((transformation == null) || transformation.isEmpty()) {
             throw new NoSuchAlgorithmException("Null or empty transformation");
         }
-        if ((provider == null) || (provider.length() == 0)) {
+        if ((provider == null) || (provider.isEmpty())) {
             throw new IllegalArgumentException("Missing provider");
         }
         Provider p = Security.getProvider(provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/crypto/SealedObject.java
--- a/src/java.base/share/classes/javax/crypto/SealedObject.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/crypto/SealedObject.java	Thu Dec 13 11:51:06 2018 -0800
@@ -337,7 +337,7 @@
         if (key == null) {
             throw new NullPointerException("key is null");
         }
-        if (provider == null || provider.length() == 0) {
+        if (provider == null || provider.isEmpty()) {
             throw new IllegalArgumentException("missing provider");
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/net/ssl/SSLSocketFactory.java
--- a/src/java.base/share/classes/javax/net/ssl/SSLSocketFactory.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/net/ssl/SSLSocketFactory.java	Thu Dec 13 11:51:06 2018 -0800
@@ -133,7 +133,7 @@
                 String s = java.security.Security.getProperty(name);
                 if (s != null) {
                     s = s.trim();
-                    if (s.length() == 0) {
+                    if (s.isEmpty()) {
                         s = null;
                     }
                 }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/PrivateCredentialPermission.java
--- a/src/java.base/share/classes/javax/security/auth/PrivateCredentialPermission.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/PrivateCredentialPermission.java	Thu Dec 13 11:51:06 2018 -0800
@@ -312,7 +312,7 @@
 
     private void init(String name) {
 
-        if (name == null || name.trim().length() == 0) {
+        if (name == null || name.trim().isEmpty()) {
             throw new IllegalArgumentException("invalid empty name");
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/callback/ChoiceCallback.java
--- a/src/java.base/share/classes/javax/security/auth/callback/ChoiceCallback.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/callback/ChoiceCallback.java	Thu Dec 13 11:51:06 2018 -0800
@@ -98,13 +98,13 @@
     public ChoiceCallback(String prompt, String[] choices,
                 int defaultChoice, boolean multipleSelectionsAllowed) {
 
-        if (prompt == null || prompt.length() == 0 ||
+        if (prompt == null || prompt.isEmpty() ||
             choices == null || choices.length == 0 ||
             defaultChoice < 0 || defaultChoice >= choices.length)
             throw new IllegalArgumentException();
 
         for (int i = 0; i < choices.length; i++) {
-            if (choices[i] == null || choices[i].length() == 0)
+            if (choices[i] == null || choices[i].isEmpty())
                 throw new IllegalArgumentException();
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/callback/ConfirmationCallback.java
--- a/src/java.base/share/classes/javax/security/auth/callback/ConfirmationCallback.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/callback/ConfirmationCallback.java	Thu Dec 13 11:51:06 2018 -0800
@@ -248,7 +248,7 @@
             throw new IllegalArgumentException();
 
         for (int i = 0; i < options.length; i++) {
-            if (options[i] == null || options[i].length() == 0)
+            if (options[i] == null || options[i].isEmpty())
                 throw new IllegalArgumentException();
         }
 
@@ -294,7 +294,7 @@
     public ConfirmationCallback(String prompt, int messageType,
                 int optionType, int defaultOption) {
 
-        if (prompt == null || prompt.length() == 0 ||
+        if (prompt == null || prompt.isEmpty() ||
             messageType < INFORMATION || messageType > ERROR ||
             optionType < YES_NO_OPTION || optionType > OK_CANCEL_OPTION)
             throw new IllegalArgumentException();
@@ -357,14 +357,14 @@
     public ConfirmationCallback(String prompt, int messageType,
                 String[] options, int defaultOption) {
 
-        if (prompt == null || prompt.length() == 0 ||
+        if (prompt == null || prompt.isEmpty() ||
             messageType < INFORMATION || messageType > ERROR ||
             options == null || options.length == 0 ||
             defaultOption < 0 || defaultOption >= options.length)
             throw new IllegalArgumentException();
 
         for (int i = 0; i < options.length; i++) {
-            if (options[i] == null || options[i].length() == 0)
+            if (options[i] == null || options[i].isEmpty())
                 throw new IllegalArgumentException();
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/callback/NameCallback.java
--- a/src/java.base/share/classes/javax/security/auth/callback/NameCallback.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/callback/NameCallback.java	Thu Dec 13 11:51:06 2018 -0800
@@ -62,7 +62,7 @@
      *                  or if {@code prompt} has a length of 0.
      */
     public NameCallback(String prompt) {
-        if (prompt == null || prompt.length() == 0)
+        if (prompt == null || prompt.isEmpty())
             throw new IllegalArgumentException();
         this.prompt = prompt;
     }
@@ -82,8 +82,8 @@
      *                  or if {@code defaultName} has a length of 0.
      */
     public NameCallback(String prompt, String defaultName) {
-        if (prompt == null || prompt.length() == 0 ||
-            defaultName == null || defaultName.length() == 0)
+        if (prompt == null || prompt.isEmpty() ||
+            defaultName == null || defaultName.isEmpty())
             throw new IllegalArgumentException();
 
         this.prompt = prompt;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/callback/PasswordCallback.java
--- a/src/java.base/share/classes/javax/security/auth/callback/PasswordCallback.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/callback/PasswordCallback.java	Thu Dec 13 11:51:06 2018 -0800
@@ -67,7 +67,7 @@
      *                  if {@code prompt} has a length of 0.
      */
     public PasswordCallback(String prompt, boolean echoOn) {
-        if (prompt == null || prompt.length() == 0)
+        if (prompt == null || prompt.isEmpty())
             throw new IllegalArgumentException();
 
         this.prompt = prompt;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/callback/TextInputCallback.java
--- a/src/java.base/share/classes/javax/security/auth/callback/TextInputCallback.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/callback/TextInputCallback.java	Thu Dec 13 11:51:06 2018 -0800
@@ -63,7 +63,7 @@
      *                  or if {@code prompt} has a length of 0.
      */
     public TextInputCallback(String prompt) {
-        if (prompt == null || prompt.length() == 0)
+        if (prompt == null || prompt.isEmpty())
             throw new IllegalArgumentException();
         this.prompt = prompt;
     }
@@ -83,8 +83,8 @@
      *                  or if {@code defaultText} has a length of 0.
      */
     public TextInputCallback(String prompt, String defaultText) {
-        if (prompt == null || prompt.length() == 0 ||
-            defaultText == null || defaultText.length() == 0)
+        if (prompt == null || prompt.isEmpty() ||
+            defaultText == null || defaultText.isEmpty())
             throw new IllegalArgumentException();
 
         this.prompt = prompt;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/callback/TextOutputCallback.java
--- a/src/java.base/share/classes/javax/security/auth/callback/TextOutputCallback.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/callback/TextOutputCallback.java	Thu Dec 13 11:51:06 2018 -0800
@@ -74,7 +74,7 @@
     public TextOutputCallback(int messageType, String message) {
         if ((messageType != INFORMATION &&
                 messageType != WARNING && messageType != ERROR) ||
-            message == null || message.length() == 0)
+            message == null || message.isEmpty())
             throw new IllegalArgumentException();
 
         this.messageType = messageType;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/login/AppConfigurationEntry.java
--- a/src/java.base/share/classes/javax/security/auth/login/AppConfigurationEntry.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/login/AppConfigurationEntry.java	Thu Dec 13 11:51:06 2018 -0800
@@ -75,7 +75,7 @@
                                 LoginModuleControlFlag controlFlag,
                                 Map<String,?> options)
     {
-        if (loginModuleName == null || loginModuleName.length() == 0 ||
+        if (loginModuleName == null || loginModuleName.isEmpty() ||
             (controlFlag != LoginModuleControlFlag.REQUIRED &&
                 controlFlag != LoginModuleControlFlag.REQUISITE &&
                 controlFlag != LoginModuleControlFlag.SUFFICIENT &&
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/login/Configuration.java
--- a/src/java.base/share/classes/javax/security/auth/login/Configuration.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/login/Configuration.java	Thu Dec 13 11:51:06 2018 -0800
@@ -418,7 +418,7 @@
                 throws NoSuchProviderException, NoSuchAlgorithmException {
 
         Objects.requireNonNull(type, "null type name");
-        if (provider == null || provider.length() == 0) {
+        if (provider == null || provider.isEmpty()) {
             throw new IllegalArgumentException("missing provider");
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/auth/login/LoginContext.java
--- a/src/java.base/share/classes/javax/security/auth/login/LoginContext.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/auth/login/LoginContext.java	Thu Dec 13 11:51:06 2018 -0800
@@ -300,7 +300,7 @@
                 public CallbackHandler run() throws Exception {
                     String defaultHandler = java.security.Security.getProperty
                         (DEFAULT_HANDLER);
-                    if (defaultHandler == null || defaultHandler.length() == 0)
+                    if (defaultHandler == null || defaultHandler.isEmpty())
                         return null;
                     Class<? extends CallbackHandler> c = Class.forName(
                             defaultHandler, true,
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/javax/security/cert/X509Certificate.java
--- a/src/java.base/share/classes/javax/security/cert/X509Certificate.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/javax/security/cert/X509Certificate.java	Thu Dec 13 11:51:06 2018 -0800
@@ -210,7 +210,7 @@
          * under JDK1.1.
          */
         String className = X509Provider;
-        if (className == null || className.length() == 0) {
+        if (className == null || className.isEmpty()) {
             // shouldn't happen, but assume corrupted properties file
             // provide access to sun implementation
             className = "com.sun.security.cert.internal.x509.X509V1CertImpl";
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/jimage/decompressor/SignatureParser.java
--- a/src/java.base/share/classes/jdk/internal/jimage/decompressor/SignatureParser.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/jimage/decompressor/SignatureParser.java	Thu Dec 13 11:51:06 2018 -0800
@@ -60,7 +60,7 @@
             switch (c) {
                 case 'L': {
                     String pkg = arguments.get(arg_index);
-                    if(pkg.length() > 0) {
+                    if(!pkg.isEmpty()) {
                         out.append(pkg).append("/");
                     }
                     arg_index+=1;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/jimage/decompressor/StringSharingDecompressor.java
--- a/src/java.base/share/classes/jdk/internal/jimage/decompressor/StringSharingDecompressor.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/jimage/decompressor/StringSharingDecompressor.java	Thu Dec 13 11:51:06 2018 -0800
@@ -168,7 +168,7 @@
                 int index = indices.get(argIndex);
                 argIndex += 1;
                 String pkg = reader.getString(index);
-                if (pkg.length() > 0) {
+                if (!pkg.isEmpty()) {
                     pkg = pkg + "/";
                     byte[] encoded = getEncoded(pkg);
                     buffer = safeAdd(buffer, encoded);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/jrtfs/JrtFileSystem.java
--- a/src/java.base/share/classes/jdk/internal/jrtfs/JrtFileSystem.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/jrtfs/JrtFileSystem.java	Thu Dec 13 11:51:06 2018 -0800
@@ -123,7 +123,7 @@
         StringBuilder sb = new StringBuilder();
         sb.append(first);
         for (String path : more) {
-            if (path.length() > 0) {
+            if (!path.isEmpty()) {
                 if (sb.length() > 0) {
                     sb.append('/');
                 }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/jrtfs/JrtPath.java
--- a/src/java.base/share/classes/jdk/internal/jrtfs/JrtPath.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/jrtfs/JrtPath.java	Thu Dec 13 11:51:06 2018 -0800
@@ -88,7 +88,7 @@
 
     @Override
     public final JrtPath getFileName() {
-        if (path.length() == 0)
+        if (path.isEmpty())
             return this;
         if (path.length() == 1 && path.charAt(0) == '/')
             return null;
@@ -210,7 +210,7 @@
         if (o.equals(this)) {
             return new JrtPath(jrtfs, "", true);
         }
-        if (path.length() == 0) {
+        if (path.isEmpty()) {
             return o;
         }
         if (jrtfs != o.jrtfs || isAbsolute() != o.isAbsolute()) {
@@ -262,16 +262,16 @@
 
     @Override
     public final boolean isAbsolute() {
-        return path.length() > 0 && path.charAt(0) == '/';
+        return !path.isEmpty() && path.charAt(0) == '/';
     }
 
     @Override
     public final JrtPath resolve(Path other) {
         final JrtPath o = checkPath(other);
-        if (this.path.length() == 0 || o.isAbsolute()) {
+        if (this.path.isEmpty() || o.isAbsolute()) {
             return o;
         }
-        if (o.path.length() == 0) {
+        if (o.path.isEmpty()) {
             return this;
         }
         StringBuilder sb = new StringBuilder(path.length() + o.path.length() + 1);
@@ -301,7 +301,7 @@
         }
         int off = op.length();
         if (off == 0) {
-            return tp.length() == 0;
+            return tp.isEmpty();
         }
         // check match is on name boundary
         return tp.length() == off || tp.charAt(off) == '/' ||
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/loader/ClassLoaders.java
--- a/src/java.base/share/classes/jdk/internal/loader/ClassLoaders.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/loader/ClassLoaders.java	Thu Dec 13 11:51:06 2018 -0800
@@ -59,7 +59,7 @@
         // -Xbootclasspath/a or -javaagent with Boot-Class-Path attribute
         String append = VM.getSavedProperty("jdk.boot.class.path.append");
         BOOT_LOADER =
-            new BootClassLoader((append != null && append.length() > 0)
+            new BootClassLoader((append != null && !append.isEmpty())
                 ? new URLClassPath(append, true)
                 : null);
         PLATFORM_LOADER = new PlatformClassLoader(BOOT_LOADER);
@@ -70,7 +70,7 @@
         // contrary, we drop this historic interpretation of the empty
         // string and instead treat it as unspecified.
         String cp = System.getProperty("java.class.path");
-        if (cp == null || cp.length() == 0) {
+        if (cp == null || cp.isEmpty()) {
             String initialModuleName = System.getProperty("jdk.module.main");
             cp = (initialModuleName == null) ? "" : null;
         }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/loader/URLClassPath.java
--- a/src/java.base/share/classes/jdk/internal/loader/URLClassPath.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/loader/URLClassPath.java	Thu Dec 13 11:51:06 2018 -0800
@@ -190,7 +190,7 @@
                 String element = (next == -1)
                     ? cp.substring(off)
                     : cp.substring(off, next);
-                if (element.length() > 0 || !skipEmptyElements) {
+                if (!element.isEmpty() || !skipEmptyElements) {
                     URL url = toFileURL(element);
                     if (url != null) path.add(url);
                 }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/module/Checks.java
--- a/src/java.base/share/classes/jdk/internal/module/Checks.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/module/Checks.java	Thu Dec 13 11:51:06 2018 -0800
@@ -63,22 +63,6 @@
     }
 
     /**
-     * Returns {@code true} if the given name is a legal module name.
-     */
-    public static boolean isModuleName(String name) {
-        int next;
-        int off = 0;
-        while ((next = name.indexOf('.', off)) != -1) {
-            String id = name.substring(off, next);
-            if (!isJavaIdentifier(id))
-                return false;
-            off = next+1;
-        }
-        String last = name.substring(off);
-        return isJavaIdentifier(last);
-    }
-
-    /**
      * Checks a name to ensure that it's a legal package name.
      *
      * @throws IllegalArgumentException if name is null or not a legal
@@ -181,20 +165,20 @@
     }
 
     /**
-     * Returns true if the given char sequence is a legal Java identifier,
+     * Returns true if the given string is a legal Java identifier,
      * otherwise false.
      */
-    private static boolean isJavaIdentifier(CharSequence cs) {
-        if (cs.length() == 0 || RESERVED.contains(cs))
+    private static boolean isJavaIdentifier(String str) {
+        if (str.isEmpty() || RESERVED.contains(str))
             return false;
 
-        int first = Character.codePointAt(cs, 0);
+        int first = Character.codePointAt(str, 0);
         if (!Character.isJavaIdentifierStart(first))
             return false;
 
         int i = Character.charCount(first);
-        while (i < cs.length()) {
-            int cp = Character.codePointAt(cs, i);
+        while (i < str.length()) {
+            int cp = Character.codePointAt(str, i);
             if (!Character.isJavaIdentifierPart(cp))
                 return false;
             i += Character.charCount(cp);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java
--- a/src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java	Thu Dec 13 11:51:06 2018 -0800
@@ -604,7 +604,8 @@
             Set<String> modules = new HashSet<>();
             while (value != null) {
                 for (String s : value.split(",")) {
-                    if (s.length() > 0) modules.add(s);
+                    if (!s.isEmpty())
+                        modules.add(s);
                 }
                 index++;
                 value = getAndRemoveProperty(prefix + index);
@@ -895,7 +896,7 @@
             List<String> values = map.computeIfAbsent(key, k -> new ArrayList<>());
             int ntargets = 0;
             for (String s : rhs.split(regex)) {
-                if (s.length() > 0) {
+                if (!s.isEmpty()) {
                     values.add(s);
                     ntargets++;
                 }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/module/ModulePatcher.java
--- a/src/java.base/share/classes/jdk/internal/module/ModulePatcher.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/module/ModulePatcher.java	Thu Dec 13 11:51:06 2018 -0800
@@ -552,7 +552,7 @@
         public Stream<String> list() throws IOException {
             return Files.walk(dir, Integer.MAX_VALUE)
                         .map(f -> Resources.toResourceName(dir, f))
-                        .filter(s -> s.length() > 0);
+                        .filter(s -> !s.isEmpty());
         }
     }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/module/ModulePath.java
--- a/src/java.base/share/classes/jdk/internal/module/ModulePath.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/module/ModulePath.java	Thu Dec 13 11:51:06 2018 -0800
@@ -546,7 +546,7 @@
                     = new BufferedReader(new InputStreamReader(in, "UTF-8"));
                 String cn;
                 while ((cn = nextLine(reader)) != null) {
-                    if (cn.length() > 0) {
+                    if (!cn.isEmpty()) {
                         String pn = packageName(cn);
                         if (!packages.contains(pn)) {
                             String msg = "Provider class " + cn + " not in module";
@@ -599,7 +599,7 @@
         mn = Patterns.REPEATING_DOTS.matcher(mn).replaceAll(".");
 
         // drop leading dots
-        if (mn.length() > 0 && mn.charAt(0) == '.')
+        if (!mn.isEmpty() && mn.charAt(0) == '.')
             mn = Patterns.LEADING_DOTS.matcher(mn).replaceAll("");
 
         // drop trailing dots
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/module/Resources.java
--- a/src/java.base/share/classes/jdk/internal/module/Resources.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/module/Resources.java	Thu Dec 13 11:51:06 2018 -0800
@@ -78,7 +78,7 @@
         String s = dir.relativize(file)
                       .toString()
                       .replace(File.separatorChar, '/');
-        if (s.length() > 0 && Files.isDirectory(file))
+        if (!s.isEmpty() && Files.isDirectory(file))
             s += "/";
         return s;
     }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/module/SystemModuleFinders.java
--- a/src/java.base/share/classes/jdk/internal/module/SystemModuleFinders.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/module/SystemModuleFinders.java	Thu Dec 13 11:51:06 2018 -0800
@@ -83,7 +83,7 @@
         if (value == null) {
             USE_FAST_PATH = true;
         } else {
-            USE_FAST_PATH = (value.length() > 0) && !Boolean.parseBoolean(value);
+            USE_FAST_PATH = !value.isEmpty() && !Boolean.parseBoolean(value);
         }
     }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/org/objectweb/asm/TypePath.java
--- a/src/java.base/share/classes/jdk/internal/org/objectweb/asm/TypePath.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/org/objectweb/asm/TypePath.java	Thu Dec 13 11:51:06 2018 -0800
@@ -147,7 +147,7 @@
       * @return the corresponding TypePath object, or {@literal null} if the path is empty.
       */
     public static TypePath fromString(final String typePath) {
-        if (typePath == null || typePath.length() == 0) {
+        if (typePath == null || typePath.isEmpty()) {
             return null;
         }
         int typePathLength = typePath.length();
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/org/objectweb/asm/util/CheckMethodAdapter.java
--- a/src/java.base/share/classes/jdk/internal/org/objectweb/asm/util/CheckMethodAdapter.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/org/objectweb/asm/util/CheckMethodAdapter.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1314,7 +1314,7 @@
       * @param message the message to use in case of error.
       */
     static void checkMethodIdentifier(final int version, final String name, final String message) {
-        if (name == null || name.length() == 0) {
+        if (name == null || name.isEmpty()) {
             throw new IllegalArgumentException(INVALID + message + MUST_NOT_BE_NULL_OR_EMPTY);
         }
         if ((version & 0xFFFF) >= Opcodes.V1_5) {
@@ -1347,7 +1347,7 @@
       * @param message the message to use in case of error.
       */
     static void checkInternalName(final int version, final String name, final String message) {
-        if (name == null || name.length() == 0) {
+        if (name == null || name.isEmpty()) {
             throw new IllegalArgumentException(INVALID + message + MUST_NOT_BE_NULL_OR_EMPTY);
         }
         if (name.charAt(0) == '[') {
@@ -1457,7 +1457,7 @@
       * @param descriptor the string to be checked.
       */
     static void checkMethodDescriptor(final int version, final String descriptor) {
-        if (descriptor == null || descriptor.length() == 0) {
+        if (descriptor == null || descriptor.isEmpty()) {
             throw new IllegalArgumentException("Invalid method descriptor (must not be null or empty)");
         }
         if (descriptor.charAt(0) != '(' || descriptor.length() < 3) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/org/objectweb/asm/util/CheckSignatureAdapter.java
--- a/src/java.base/share/classes/jdk/internal/org/objectweb/asm/util/CheckSignatureAdapter.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/org/objectweb/asm/util/CheckSignatureAdapter.java	Thu Dec 13 11:51:06 2018 -0800
@@ -365,7 +365,7 @@
     }
 
     private void checkClassName(final String name, final String message) {
-        if (name == null || name.length() == 0) {
+        if (name == null || name.isEmpty()) {
             throw new IllegalArgumentException(INVALID + message + " (must not be null or empty)");
         }
         for (int i = 0; i < name.length(); ++i) {
@@ -377,7 +377,7 @@
     }
 
     private void checkIdentifier(final String name, final String message) {
-        if (name == null || name.length() == 0) {
+        if (name == null || name.isEmpty()) {
             throw new IllegalArgumentException(INVALID + message + " (must not be null or empty)");
         }
         for (int i = 0; i < name.length(); ++i) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/reflect/UnsafeFieldAccessorImpl.java
--- a/src/java.base/share/classes/jdk/internal/reflect/UnsafeFieldAccessorImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/reflect/UnsafeFieldAccessorImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -151,10 +151,10 @@
         if (isFinal)
             err += " final";
         err += " " + field.getType().getName() + " field " + getQualifiedFieldName() + " to ";
-        if (attemptedValue.length() > 0) {
+        if (!attemptedValue.isEmpty()) {
             err += "(" + attemptedType + ")" + attemptedValue;
         } else {
-            if (attemptedType.length() > 0)
+            if (!attemptedType.isEmpty())
                 err += attemptedType;
             else
                 err += "null value";
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/util/jar/JarIndex.java
--- a/src/java.base/share/classes/jdk/internal/util/jar/JarIndex.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/util/jar/JarIndex.java	Thu Dec 13 11:51:06 2018 -0800
@@ -291,7 +291,7 @@
         while((line = br.readLine()) != null && !line.endsWith(".jar"));
 
         for(;line != null; line = br.readLine()) {
-            if (line.length() == 0)
+            if (line.isEmpty())
                 continue;
 
             if (line.endsWith(".jar")) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/util/xml/PropertiesDefaultHandler.java
--- a/src/java.base/share/classes/jdk/internal/util/xml/PropertiesDefaultHandler.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/util/xml/PropertiesDefaultHandler.java	Thu Dec 13 11:51:06 2018 -0800
@@ -103,7 +103,7 @@
             writer.writeStartDocument();
             writer.writeDTD(PROPS_DTD_DECL);
             writer.writeStartElement(ELEMENT_ROOT);
-            if (comment != null && comment.length() > 0) {
+            if (comment != null && !comment.isEmpty()) {
                 writer.writeStartElement(ELEMENT_COMMENT);
                 writer.writeCharacters(comment);
                 writer.writeEndElement();
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/util/xml/impl/Parser.java
--- a/src/java.base/share/classes/jdk/internal/util/xml/impl/Parser.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/util/xml/impl/Parser.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1591,7 +1591,7 @@
                             str = name(false);
                             //          PI target name may not be empty string [#2.6]
                             //          PI target name 'XML' is reserved [#2.6]
-                            if ((str.length() == 0)
+                            if ((str.isEmpty())
                                     || (mXml.name.equals(str.toLowerCase()) == true)) {
                                 panic(FAULT);
                             }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/jdk/internal/util/xml/impl/XMLStreamWriterImpl.java
--- a/src/java.base/share/classes/jdk/internal/util/xml/impl/XMLStreamWriterImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/jdk/internal/util/xml/impl/XMLStreamWriterImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -205,7 +205,7 @@
      * @throws XMLStreamException
      */
     public void writeStartElement(String localName) throws XMLStreamException {
-        if (localName == null || localName.length() == 0) {
+        if (localName == null || localName.isEmpty()) {
             throw new XMLStreamException("Local Name cannot be null or empty");
         }
 
@@ -420,7 +420,7 @@
     }
 
     private void writeXMLContent(String content) throws XMLStreamException {
-        if ((content != null) && (content.length() > 0)) {
+        if (content != null && !content.isEmpty()) {
             writeXMLContent(content,
                     _escapeCharacters, // boolean = escapeChars
                     false);             // false = escapeDoubleQuotes
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/invoke/util/BytecodeName.java
--- a/src/java.base/share/classes/sun/invoke/util/BytecodeName.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/invoke/util/BytecodeName.java	Thu Dec 13 11:51:06 2018 -0800
@@ -451,7 +451,7 @@
      * @return true if the name is non-empty and all of its characters are safe
      */
     public static boolean isSafeBytecodeName(String s) {
-        if (s.length() == 0)  return false;
+        if (s.isEmpty())  return false;
         // check occurrences of each DANGEROUS char
         for (char xc : DANGEROUS_CHARS_A) {
             if (xc == ESCAPE_C)  continue;  // not really that dangerous
@@ -476,7 +476,7 @@
     }
 
     private static String mangle(String s) {
-        if (s.length() == 0)
+        if (s.isEmpty())
             return NULL_ESCAPE;
 
         // build this lazily, when we first need an escape:
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/TransferProtocolClient.java
--- a/src/java.base/share/classes/sun/net/TransferProtocolClient.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/TransferProtocolClient.java	Thu Dec 13 11:51:06 2018 -0800
@@ -76,7 +76,7 @@
                 System.out.print(response);
             }
 
-            if (response.length() == 0) {
+            if (response.isEmpty()) {
                 code = -1;
             } else {
                 try {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/ftp/impl/FtpClient.java
--- a/src/java.base/share/classes/sun/net/ftp/impl/FtpClient.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/ftp/impl/FtpClient.java	Thu Dec 13 11:51:06 2018 -0800
@@ -433,7 +433,7 @@
                 logger.finest("Server [" + serverAddr + "] --> " + response);
             }
 
-            if (response.length() == 0) {
+            if (response.isEmpty()) {
                 code = -1;
             } else {
                 try {
@@ -1049,7 +1049,7 @@
         if (!isConnected()) {
             throw new sun.net.ftp.FtpProtocolException("Not connected yet", FtpReplyCode.BAD_SEQUENCE);
         }
-        if (user == null || user.length() == 0) {
+        if (user == null || user.isEmpty()) {
             throw new IllegalArgumentException("User name can't be null or empty");
         }
         tryLogin(user, password);
@@ -1088,7 +1088,7 @@
         if (!isConnected()) {
             throw new sun.net.ftp.FtpProtocolException("Not connected yet", FtpReplyCode.BAD_SEQUENCE);
         }
-        if (user == null || user.length() == 0) {
+        if (user == null || user.isEmpty()) {
             throw new IllegalArgumentException("User name can't be null or empty");
         }
         tryLogin(user, password);
@@ -1152,7 +1152,7 @@
      * @exception <code>FtpProtocolException</code>
      */
     public sun.net.ftp.FtpClient changeDirectory(String remoteDirectory) throws sun.net.ftp.FtpProtocolException, IOException {
-        if (remoteDirectory == null || "".equals(remoteDirectory)) {
+        if (remoteDirectory == null || remoteDirectory.isEmpty()) {
             throw new IllegalArgumentException("directory can't be null or empty");
         }
 
@@ -1738,7 +1738,7 @@
      * @throws IOException if an error occurs during the transmission.
      */
     public long getSize(String path) throws sun.net.ftp.FtpProtocolException, IOException {
-        if (path == null || path.length() == 0) {
+        if (path == null || path.isEmpty()) {
             throw new IllegalArgumentException("path can't be null or empty");
         }
         issueCommandCheck("SIZE " + path);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/spi/DefaultProxySelector.java
--- a/src/java.base/share/classes/sun/net/spi/DefaultProxySelector.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/spi/DefaultProxySelector.java	Thu Dec 13 11:51:06 2018 -0800
@@ -238,7 +238,7 @@
                                 if (phost != null && phost.length() != 0)
                                     break;
                             }
-                            if (phost == null || phost.length() == 0) {
+                            if (phost == null || phost.isEmpty()) {
                                 /**
                                  * No system property defined for that
                                  * protocol. Let's check System Proxy
@@ -267,7 +267,7 @@
                                             nprop.hostsSource = null;
                                             nprop.pattern = null;
                                         }
-                                    } else if (nphosts.length() != 0) {
+                                    } else if (!nphosts.isEmpty()) {
                                         // add the required default patterns
                                         // but only if property no set. If it
                                         // is empty, leave empty.
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/HeaderParser.java
--- a/src/java.base/share/classes/sun/net/www/HeaderParser.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/HeaderParser.java	Thu Dec 13 11:51:06 2018 -0800
@@ -226,7 +226,7 @@
         for (int i=0; k.hasNext(); i++) {
             String key = k.next();
             String val = findValue (i);
-            if (val != null && "".equals (val)) {
+            if (val != null && val.isEmpty()) {
                 val = null;
             }
             sb.append(" {").append(key).append(val == null ? "" : "," + val)
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/MimeEntry.java
--- a/src/java.base/share/classes/sun/net/www/MimeEntry.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/MimeEntry.java	Thu Dec 13 11:51:06 2018 -0800
@@ -201,9 +201,7 @@
     }
 
     private boolean isStarred(String typeName) {
-        return (typeName != null)
-            && (typeName.length() > 0)
-            && (typeName.endsWith("/*"));
+        return typeName != null && typeName.endsWith("/*");
     }
 
     /**
@@ -300,7 +298,7 @@
         }
 
         String extensions = getExtensionsAsList();
-        if (extensions.length() > 0) {
+        if (!extensions.isEmpty()) {
             sj.add("file_extensions=" + extensions);
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/MimeLauncher.java
--- a/src/java.base/share/classes/sun/net/www/MimeLauncher.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/MimeLauncher.java	Thu Dec 13 11:51:06 2018 -0800
@@ -162,7 +162,7 @@
        location the application.  If a valid path is not found, it
        returns false else true.  */
     private boolean findExecutablePath(String str) {
-        if (str == null || str.length() == 0) {
+        if (str == null || str.isEmpty()) {
             return false;
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/ParseUtil.java
--- a/src/java.base/share/classes/sun/net/www/ParseUtil.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/ParseUtil.java	Thu Dec 13 11:51:06 2018 -0800
@@ -536,8 +536,7 @@
         throws URISyntaxException
     {
         if (scheme != null) {
-            if ((path != null)
-                && ((path.length() > 0) && (path.charAt(0) != '/')))
+            if (path != null && !path.isEmpty() && path.charAt(0) != '/')
                 throw new URISyntaxException(s,
                                              "Relative path in absolute URI");
         }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/http/HttpClient.java
--- a/src/java.base/share/classes/sun/net/www/http/HttpClient.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/http/HttpClient.java	Thu Dec 13 11:51:06 2018 -0800
@@ -603,7 +603,7 @@
             StringBuilder result = new StringBuilder(128);
             result.append(url.getProtocol());
             result.append(":");
-            if (url.getAuthority() != null && url.getAuthority().length() > 0) {
+            if (url.getAuthority() != null && !url.getAuthority().isEmpty()) {
                 result.append("//");
                 result.append(url.getAuthority());
             }
@@ -619,7 +619,7 @@
         } else {
             fileName = url.getFile();
 
-            if ((fileName == null) || (fileName.length() == 0)) {
+            if ((fileName == null) || (fileName.isEmpty())) {
                 fileName = "/";
             } else if (fileName.charAt(0) == '?') {
                 /* HTTP/1.1 spec says in 5.1.2. about Request-URI:
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/protocol/ftp/FtpURLConnection.java
--- a/src/java.base/share/classes/sun/net/www/protocol/ftp/FtpURLConnection.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/protocol/ftp/FtpURLConnection.java	Thu Dec 13 11:51:06 2018 -0800
@@ -341,7 +341,7 @@
                 path.charAt(0) == '/') {
             path = path.substring(1);
         }
-        if (path == null || path.length() == 0) {
+        if (path == null || path.isEmpty()) {
             path = "./";
         }
         if (!path.endsWith("/")) {
@@ -555,7 +555,7 @@
         }
 
         decodePath(url.getPath());
-        if (filename == null || filename.length() == 0) {
+        if (filename == null || filename.isEmpty()) {
             throw new IOException("illegal filename for a PUT");
         }
         try {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/protocol/http/AuthenticationInfo.java
--- a/src/java.base/share/classes/sun/net/www/protocol/http/AuthenticationInfo.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/protocol/http/AuthenticationInfo.java	Thu Dec 13 11:51:06 2018 -0800
@@ -248,7 +248,7 @@
         this.realm = realm;
 
         String urlPath = url.getPath();
-        if (urlPath.length() == 0)
+        if (urlPath.isEmpty())
             this.path = urlPath;
         else {
             this.path = reducePath (urlPath);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/protocol/http/DigestAuthentication.java
--- a/src/java.base/share/classes/sun/net/www/protocol/http/DigestAuthentication.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/protocol/http/DigestAuthentication.java	Thu Dec 13 11:51:06 2018 -0800
@@ -279,7 +279,7 @@
         if (s == null || !s.equals("true"))
             return false;
         String newNonce = p.findValue ("nonce");
-        if (newNonce == null || "".equals(newNonce)) {
+        if (newNonce == null || newNonce.isEmpty()) {
             return false;
         }
         params.setNonce (newNonce);
@@ -323,7 +323,7 @@
                         + authMethod.substring(1).toLowerCase();
         }
         String algorithm = p.findValue("algorithm");
-        if (algorithm == null || "".equals(algorithm)) {
+        if (algorithm == null || algorithm.isEmpty()) {
             algorithm = "MD5";  // The default, accoriding to rfc2069
         }
         params.setAlgorithm (algorithm);
@@ -451,7 +451,7 @@
             }
             /* Check if there is a nextnonce field */
             String nextnonce = p.findValue ("nextnonce");
-            if (nextnonce != null && ! "".equals(nextnonce)) {
+            if (nextnonce != null && !nextnonce.isEmpty()) {
                 params.setNonce (nextnonce);
             }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/protocol/http/HttpURLConnection.java
--- a/src/java.base/share/classes/sun/net/www/protocol/http/HttpURLConnection.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/protocol/http/HttpURLConnection.java	Thu Dec 13 11:51:06 2018 -0800
@@ -3026,7 +3026,7 @@
 
             // Filtering only if there is a cookie handler. [Assumption: the
             // cookie handler will store/retrieve the HttpOnly cookies]
-            if (cookieHandler == null || value.length() == 0)
+            if (cookieHandler == null || value.isEmpty())
                 return value;
 
             JavaNetHttpCookieAccess access =
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/protocol/https/HttpsClient.java
--- a/src/java.base/share/classes/sun/net/www/protocol/https/HttpsClient.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/protocol/https/HttpsClient.java	Thu Dec 13 11:51:06 2018 -0800
@@ -143,7 +143,7 @@
         String cipherString =
                 GetPropertyAction.privilegedGetProperty("https.cipherSuites");
 
-        if (cipherString == null || "".equals(cipherString)) {
+        if (cipherString == null || cipherString.isEmpty()) {
             ciphers = null;
         } else {
             StringTokenizer     tokenizer;
@@ -167,7 +167,7 @@
         String protocolString =
                 GetPropertyAction.privilegedGetProperty("https.protocols");
 
-        if (protocolString == null || "".equals(protocolString)) {
+        if (protocolString == null || protocolString.isEmpty()) {
             protocols = null;
         } else {
             StringTokenizer     tokenizer;
@@ -187,7 +187,7 @@
     private String getUserAgent() {
         String userAgent =
                 GetPropertyAction.privilegedGetProperty("https.agent");
-        if (userAgent == null || userAgent.length() == 0) {
+        if (userAgent == null || userAgent.isEmpty()) {
             userAgent = "JSSE";
         }
         return userAgent;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/net/www/protocol/jrt/JavaRuntimeURLConnection.java
--- a/src/java.base/share/classes/sun/net/www/protocol/jrt/JavaRuntimeURLConnection.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/net/www/protocol/jrt/JavaRuntimeURLConnection.java	Thu Dec 13 11:51:06 2018 -0800
@@ -66,7 +66,7 @@
     JavaRuntimeURLConnection(URL url) throws IOException {
         super(url);
         String path = url.getPath();
-        if (path.length() == 0 || path.charAt(0) != '/')
+        if (path.isEmpty() || path.charAt(0) != '/')
             throw new MalformedURLException(url + " missing path or /");
         if (path.length() == 1) {
             this.module = null;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/nio/ch/Net.java
--- a/src/java.base/share/classes/sun/nio/ch/Net.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/nio/ch/Net.java	Thu Dec 13 11:51:06 2018 -0800
@@ -403,14 +403,8 @@
 
     public static boolean isFastTcpLoopbackRequested() {
         String loopbackProp = GetPropertyAction
-                .privilegedGetProperty("jdk.net.useFastTcpLoopback");
-        boolean enable;
-        if ("".equals(loopbackProp)) {
-            enable = true;
-        } else {
-            enable = Boolean.parseBoolean(loopbackProp);
-        }
-        return enable;
+                .privilegedGetProperty("jdk.net.useFastTcpLoopback", "false");
+        return loopbackProp.isEmpty() ? true : Boolean.parseBoolean(loopbackProp);
     }
 
     // -- Socket operations --
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/nio/fs/AbstractFileSystemProvider.java
--- a/src/java.base/share/classes/sun/nio/fs/AbstractFileSystemProvider.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/nio/fs/AbstractFileSystemProvider.java	Thu Dec 13 11:51:06 2018 -0800
@@ -73,7 +73,7 @@
         throws IOException
     {
         String[] s = split(attribute);
-        if (s[0].length() == 0)
+        if (s[0].isEmpty())
             throw new IllegalArgumentException(attribute);
         DynamicFileAttributeView view = getFileAttributeView(file, s[0], options);
         if (view == null)
@@ -86,7 +86,7 @@
         throws IOException
     {
         String[] s = split(attributes);
-        if (s[0].length() == 0)
+        if (s[0].isEmpty())
             throw new IllegalArgumentException(attributes);
         DynamicFileAttributeView view = getFileAttributeView(file, s[0], options);
         if (view == null)
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/nio/fs/AbstractUserDefinedFileAttributeView.java
--- a/src/java.base/share/classes/sun/nio/fs/AbstractUserDefinedFileAttributeView.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/nio/fs/AbstractUserDefinedFileAttributeView.java	Thu Dec 13 11:51:06 2018 -0800
@@ -83,7 +83,7 @@
                 names = list();
                 break;
             } else {
-                if (name.length() == 0)
+                if (name.isEmpty())
                     throw new IllegalArgumentException();
                 names.add(name);
             }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/jca/GetInstance.java
--- a/src/java.base/share/classes/sun/security/jca/GetInstance.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/jca/GetInstance.java	Thu Dec 13 11:51:06 2018 -0800
@@ -75,7 +75,7 @@
     public static Service getService(String type, String algorithm,
             String provider) throws NoSuchAlgorithmException,
             NoSuchProviderException {
-        if ((provider == null) || (provider.length() == 0)) {
+        if (provider == null || provider.isEmpty()) {
             throw new IllegalArgumentException("missing provider");
         }
         Provider p = Providers.getProviderList().getProvider(provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/jca/ProviderConfig.java
--- a/src/java.base/share/classes/sun/security/jca/ProviderConfig.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/jca/ProviderConfig.java	Thu Dec 13 11:51:06 2018 -0800
@@ -114,7 +114,7 @@
     }
 
     private boolean hasArgument() {
-        return argument.length() != 0;
+        return !argument.isEmpty();
     }
 
     // should we try to load this provider?
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/jca/ProviderList.java
--- a/src/java.base/share/classes/sun/security/jca/ProviderList.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/jca/ProviderList.java	Thu Dec 13 11:51:06 2018 -0800
@@ -175,7 +175,7 @@
 
         while ((entry = Security.getProperty("security.provider." + i)) != null) {
             entry = entry.trim();
-            if (entry.length() == 0) {
+            if (entry.isEmpty()) {
                 System.err.println("invalid entry for " +
                                    "security.provider." + i);
                 break;
@@ -200,7 +200,7 @@
 
         // Load config entries for use when getInstance is called
         entry = Security.getProperty("jdk.security.provider.preferred");
-        if (entry != null && (entry = entry.trim()).length() > 0) {
+        if (entry != null && !(entry = entry.trim()).isEmpty()) {
             String[] entries = entry.split(",");
             if (ProviderList.preferredPropList == null) {
                 ProviderList.preferredPropList = new PreferredList();
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/provider/ConfigFile.java
--- a/src/java.base/share/classes/sun/security/provider/ConfigFile.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/provider/ConfigFile.java	Thu Dec 13 11:51:06 2018 -0800
@@ -626,7 +626,7 @@
                     return url.openStream();
                 } catch (Exception e) {
                     String file = url.getPath();
-                    if (url.getHost().length() > 0) {  // For Windows UNC
+                    if (!url.getHost().isEmpty()) {  // For Windows UNC
                         file = "//" + url.getHost() + file;
                     }
                     if (debugConfig != null) {
@@ -651,7 +651,7 @@
                 return value;
             }
             String s = PropertyExpander.expand(value);
-            if (s == null || s.length() == 0) {
+            if (s == null || s.isEmpty()) {
                 throw ioException(
                     "Configuration.Error.Line.line.system.property.value.expanded.to.empty.value",
                     linenum, value);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/provider/PolicyParser.java
--- a/src/java.base/share/classes/sun/security/provider/PolicyParser.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/provider/PolicyParser.java	Thu Dec 13 11:51:06 2018 -0800
@@ -391,9 +391,9 @@
         out.print("keystore \"");
         out.print(keyStoreUrlString);
         out.print('"');
-        if (keyStoreType != null && keyStoreType.length() > 0)
+        if (keyStoreType != null && !keyStoreType.isEmpty())
             out.print(", \"" + keyStoreType + "\"");
-        if (keyStoreProvider != null && keyStoreProvider.length() > 0)
+        if (keyStoreProvider != null && !keyStoreProvider.isEmpty())
             out.print(", \"" + keyStoreProvider + "\"");
         out.println(";");
         out.println();
@@ -446,7 +446,7 @@
                     String alias = aliases.nextToken().trim();
                     if (alias.equals(","))
                         cctr++;
-                    else if (alias.length() > 0)
+                    else if (!alias.isEmpty())
                         actr++;
                 }
                 if (actr <= cctr)
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/provider/SeedGenerator.java
--- a/src/java.base/share/classes/sun/security/provider/SeedGenerator.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/provider/SeedGenerator.java	Thu Dec 13 11:51:06 2018 -0800
@@ -113,7 +113,7 @@
                                   + "generator: " + e.toString());
                 }
             }
-        } else if (egdSource.length() != 0) {
+        } else if (!egdSource.isEmpty()) {
             try {
                 instance = new URLSeedGenerator(egdSource);
                 if (debug != null) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/ssl/CertificateMessage.java
--- a/src/java.base/share/classes/sun/security/ssl/CertificateMessage.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/ssl/CertificateMessage.java	Thu Dec 13 11:51:06 2018 -0800
@@ -440,7 +440,7 @@
                 // It is not necessary to check the certificate update if
                 // endpoint identification is enabled.
                 String identityAlg = chc.sslConfig.identificationProtocol;
-                if ((identityAlg == null || identityAlg.length() == 0) &&
+                if ((identityAlg == null || identityAlg.isEmpty()) &&
                         !isIdentityEquivalent(x509Certs[0],
                                 chc.reservedServerCerts[0])) {
                     chc.conContext.fatal(Alert.BAD_CERTIFICATE,
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/ssl/ClientHello.java
--- a/src/java.base/share/classes/sun/security/ssl/ClientHello.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/ssl/ClientHello.java	Thu Dec 13 11:51:06 2018 -0800
@@ -491,7 +491,7 @@
                     // It is fine to move on with abbreviate handshake if
                     // endpoint identification is enabled.
                     String identityAlg = chc.sslConfig.identificationProtocol;
-                    if ((identityAlg == null || identityAlg.length() == 0)) {
+                    if (identityAlg == null || identityAlg.isEmpty()) {
                         if (isEmsAvailable) {
                             if (!session.useExtendedMasterSecret) {
                                 // perform full handshake instead
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/ssl/DHKeyExchange.java
--- a/src/java.base/share/classes/sun/security/ssl/DHKeyExchange.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/ssl/DHKeyExchange.java	Thu Dec 13 11:51:06 2018 -0800
@@ -253,7 +253,7 @@
         static {
             String property = GetPropertyAction.privilegedGetProperty(
                     "jdk.tls.ephemeralDHKeySize");
-            if (property == null || property.length() == 0) {
+            if (property == null || property.isEmpty()) {
                 useLegacyEphemeralDHKeys = false;
                 useSmartEphemeralDHKeys = false;
                 customizedDHKeySize = -1;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/ssl/SSLAlgorithmConstraints.java
--- a/src/java.base/share/classes/sun/security/ssl/SSLAlgorithmConstraints.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/ssl/SSLAlgorithmConstraints.java	Thu Dec 13 11:51:06 2018 -0800
@@ -237,7 +237,7 @@
         public boolean permits(Set<CryptoPrimitive> primitives,
                 String algorithm, AlgorithmParameters parameters) {
 
-            if (algorithm == null || algorithm.length() == 0) {
+            if (algorithm == null || algorithm.isEmpty()) {
                 throw new IllegalArgumentException(
                         "No algorithm name specified");
             }
@@ -276,7 +276,7 @@
         public final boolean permits(Set<CryptoPrimitive> primitives,
                 String algorithm, Key key, AlgorithmParameters parameters) {
 
-            if (algorithm == null || algorithm.length() == 0) {
+            if (algorithm == null || algorithm.isEmpty()) {
                 throw new IllegalArgumentException(
                         "No algorithm name specified");
             }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/ssl/SSLContextImpl.java
--- a/src/java.base/share/classes/sun/security/ssl/SSLContextImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/ssl/SSLContextImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -436,7 +436,7 @@
                     "System property " + propertyName + " is set to '" +
                     property + "'");
         }
-        if (property != null && property.length() != 0) {
+        if (property != null && !property.isEmpty()) {
             // remove double quote marks from beginning/end of the property
             if (property.length() > 1 && property.charAt(0) == '"' &&
                     property.charAt(property.length() - 1) == '"') {
@@ -444,7 +444,7 @@
             }
         }
 
-        if (property != null && property.length() != 0) {
+        if (property != null && !property.isEmpty()) {
             String[] cipherSuiteNames = property.split(",");
             Collection<CipherSuite> cipherSuites =
                         new ArrayList<>(cipherSuiteNames.length);
@@ -845,7 +845,7 @@
                 return;
             }
 
-            if (property.length() != 0) {
+            if (!property.isEmpty()) {
                 // remove double quote marks from beginning/end of the property
                 if (property.length() > 1 && property.charAt(0) == '"' &&
                         property.charAt(property.length() - 1) == '"') {
@@ -853,7 +853,7 @@
                 }
             }
 
-            if (property.length() != 0) {
+            if (!property.isEmpty()) {
                 String[] protocols = property.split(",");
                 for (int i = 0; i < protocols.length; i++) {
                     protocols[i] = protocols[i].trim();
@@ -1109,7 +1109,7 @@
             KeyStore ks = null;
             char[] passwd = null;
             try {
-                if (defaultKeyStore.length() != 0 &&
+                if (!defaultKeyStore.isEmpty() &&
                         !NONE.equals(defaultKeyStore)) {
                     fs = AccessController.doPrivileged(
                             new PrivilegedExceptionAction<FileInputStream>() {
@@ -1121,7 +1121,7 @@
                 }
 
                 String defaultKeyStorePassword = props.get("keyStorePasswd");
-                if (defaultKeyStorePassword.length() != 0) {
+                if (!defaultKeyStorePassword.isEmpty()) {
                     passwd = defaultKeyStorePassword.toCharArray();
                 }
 
@@ -1132,7 +1132,7 @@
                     if (SSLLogger.isOn && SSLLogger.isOn("ssl,defaultctx")) {
                         SSLLogger.finest("init keystore");
                     }
-                    if (defaultKeyStoreProvider.length() == 0) {
+                    if (defaultKeyStoreProvider.isEmpty()) {
                         ks = KeyStore.getInstance(defaultKeyStoreType);
                     } else {
                         ks = KeyStore.getInstance(defaultKeyStoreType,
@@ -1561,7 +1561,7 @@
             // check endpoint identity
             String identityAlg = sslSocket.getSSLParameters().
                                         getEndpointIdentificationAlgorithm();
-            if (identityAlg != null && identityAlg.length() != 0) {
+            if (identityAlg != null && !identityAlg.isEmpty()) {
                 String hostname = session.getPeerHost();
                 X509TrustManagerImpl.checkIdentity(
                                     hostname, chain[0], identityAlg);
@@ -1601,7 +1601,7 @@
             // check endpoint identity
             String identityAlg = engine.getSSLParameters().
                                         getEndpointIdentificationAlgorithm();
-            if (identityAlg != null && identityAlg.length() != 0) {
+            if (identityAlg != null && !identityAlg.isEmpty()) {
                 String hostname = session.getPeerHost();
                 X509TrustManagerImpl.checkIdentity(
                                     hostname, chain[0], identityAlg);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java
--- a/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1203,7 +1203,7 @@
     synchronized void doneConnect() throws IOException {
         // In server mode, it is not necessary to set host and serverNames.
         // Otherwise, would require a reverse DNS lookup to get the hostname.
-        if ((peerHost == null) || (peerHost.length() == 0)) {
+        if (peerHost == null || peerHost.isEmpty()) {
             boolean useNameService =
                     trustNameService && conContext.sslConfig.isClientMode;
             useImplicitHost(useNameService);
@@ -1238,8 +1238,7 @@
         JavaNetInetAddressAccess jna =
                 SharedSecrets.getJavaNetInetAddressAccess();
         String originalHostname = jna.getOriginalHostName(inetAddress);
-        if ((originalHostname != null) &&
-                (originalHostname.length() != 0)) {
+        if (originalHostname != null && !originalHostname.isEmpty()) {
 
             this.peerHost = originalHostname;
             if (conContext.sslConfig.serverNames.isEmpty() &&
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/ssl/SupportedGroupsExtension.java
--- a/src/java.base/share/classes/sun/security/ssl/SupportedGroupsExtension.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/ssl/SupportedGroupsExtension.java	Thu Dec 13 11:51:06 2018 -0800
@@ -483,7 +483,7 @@
             // default groups and preferences will be used.
             String property = GetPropertyAction
                     .privilegedGetProperty("jdk.tls.namedGroups");
-            if (property != null && property.length() != 0) {
+            if (property != null && !property.isEmpty()) {
                 // remove double quote marks from beginning/end of the property
                 if (property.length() > 1 && property.charAt(0) == '"' &&
                         property.charAt(property.length() - 1) == '"') {
@@ -492,7 +492,7 @@
             }
 
             ArrayList<NamedGroup> groupList;
-            if (property != null && property.length() != 0) {
+            if (property != null && !property.isEmpty()) {
                 String[] groups = property.split(",");
                 groupList = new ArrayList<>(groups.length);
                 for (String group : groups) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/ssl/X509TrustManagerImpl.java
--- a/src/java.base/share/classes/sun/security/ssl/X509TrustManagerImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/ssl/X509TrustManagerImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -148,7 +148,7 @@
                 "null or zero-length certificate chain");
         }
 
-        if (authType == null || authType.length() == 0) {
+        if (authType == null || authType.isEmpty()) {
             throw new IllegalArgumentException(
                 "null or zero-length authentication type");
         }
@@ -229,7 +229,7 @@
             // check endpoint identity
             String identityAlg = sslSocket.getSSLParameters().
                     getEndpointIdentificationAlgorithm();
-            if (identityAlg != null && identityAlg.length() != 0) {
+            if (identityAlg != null && !identityAlg.isEmpty()) {
                 checkIdentity(session, trustedChain[0], identityAlg, isClient,
                         getRequestedServerNames(socket), chainsToPublicCA);
             }
@@ -287,7 +287,7 @@
             // check endpoint identity
             String identityAlg = engine.getSSLParameters().
                     getEndpointIdentificationAlgorithm();
-            if (identityAlg != null && identityAlg.length() != 0) {
+            if (identityAlg != null && !identityAlg.isEmpty()) {
                 checkIdentity(session, trustedChain[0], identityAlg, isClient,
                         getRequestedServerNames(engine), chainsToPublicCA);
             }
@@ -448,7 +448,7 @@
     private static void checkIdentity(String hostname, X509Certificate cert,
             String algorithm, boolean chainsToPublicCA)
             throws CertificateException {
-        if (algorithm != null && algorithm.length() != 0) {
+        if (algorithm != null && !algorithm.isEmpty()) {
             // if IPv6 strip off the "[]"
             if ((hostname != null) && hostname.startsWith("[") &&
                     hostname.endsWith("]")) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/tools/PathList.java
--- a/src/java.base/share/classes/sun/security/tools/PathList.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/tools/PathList.java	Thu Dec 13 11:51:06 2018 -0800
@@ -46,9 +46,9 @@
      * @return the resulting path
      */
     public static String appendPath(String pathTo, String pathFrom) {
-        if (pathTo == null || pathTo.length() == 0) {
+        if (pathTo == null || pathTo.isEmpty()) {
             return pathFrom;
-        } else if (pathFrom == null || pathFrom.length() == 0) {
+        } else if (pathFrom == null || pathFrom.isEmpty()) {
             return pathTo;
         } else {
             return pathTo  + File.pathSeparator + pathFrom;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/util/AbstractAlgorithmConstraints.java
--- a/src/java.base/share/classes/sun/security/util/AbstractAlgorithmConstraints.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/util/AbstractAlgorithmConstraints.java	Thu Dec 13 11:51:06 2018 -0800
@@ -75,7 +75,7 @@
 
     static boolean checkAlgorithm(String[] algorithms, String algorithm,
             AlgorithmDecomposer decomposer) {
-        if (algorithm == null || algorithm.length() == 0) {
+        if (algorithm == null || algorithm.isEmpty()) {
             throw new IllegalArgumentException("No algorithm name specified");
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/util/AlgorithmDecomposer.java
--- a/src/java.base/share/classes/sun/security/util/AlgorithmDecomposer.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/util/AlgorithmDecomposer.java	Thu Dec 13 11:51:06 2018 -0800
@@ -80,7 +80,7 @@
      * Please override the method if need to support more name pattern.
      */
     public Set<String> decompose(String algorithm) {
-        if (algorithm == null || algorithm.length() == 0) {
+        if (algorithm == null || algorithm.isEmpty()) {
             return new HashSet<>();
         }
 
@@ -167,7 +167,7 @@
      * message digest algorithm name to avoid overly complicated checking.
      */
     public static Set<String> decomposeOneHash(String algorithm) {
-        if (algorithm == null || algorithm.length() == 0) {
+        if (algorithm == null || algorithm.isEmpty()) {
             return new HashSet<>();
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/util/DisabledAlgorithmConstraints.java
--- a/src/java.base/share/classes/sun/security/util/DisabledAlgorithmConstraints.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/util/DisabledAlgorithmConstraints.java	Thu Dec 13 11:51:06 2018 -0800
@@ -135,7 +135,7 @@
     public final boolean permits(Set<CryptoPrimitive> primitives,
             String algorithm, Key key, AlgorithmParameters parameters) {
 
-        if (algorithm == null || algorithm.length() == 0) {
+        if (algorithm == null || algorithm.isEmpty()) {
             throw new IllegalArgumentException("No algorithm name specified");
         }
 
@@ -188,7 +188,7 @@
         }
 
         // check the signature algorithm with parameters
-        if (algorithm != null && algorithm.length() != 0) {
+        if (algorithm != null && !algorithm.isEmpty()) {
             if (!permits(primitives, algorithm, parameters)) {
                 return false;
             }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/util/SignatureFileVerifier.java
--- a/src/java.base/share/classes/sun/security/util/SignatureFileVerifier.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/util/SignatureFileVerifier.java	Thu Dec 13 11:51:06 2018 -0800
@@ -423,7 +423,7 @@
 
         // This means we have an error in finding weak algorithms, run in
         // debug mode to see permittedAlgs map's values.
-        if (w.length() == 0) {
+        if (w.isEmpty()) {
             return "Unknown Algorithm(s)";
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/x509/AVA.java
--- a/src/java.base/share/classes/sun/security/x509/AVA.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/x509/AVA.java	Thu Dec 13 11:51:06 2018 -0800
@@ -1245,7 +1245,7 @@
         }
 
         boolean number = false;
-        if (keyword.length() != 0) {
+        if (!keyword.isEmpty()) {
             char ch = keyword.charAt(0);
             if ((ch >= '0') && (ch <= '9')) {
                 number = true;
@@ -1285,7 +1285,7 @@
                 return ak.keyword;
             }
         } else {
-            if (keywordString.length() == 0) {
+            if (keywordString.isEmpty()) {
                 throw new IllegalArgumentException("keyword cannot be empty");
             }
             keywordString = keywordString.trim();
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/x509/DNSName.java
--- a/src/java.base/share/classes/sun/security/x509/DNSName.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/x509/DNSName.java	Thu Dec 13 11:51:06 2018 -0800
@@ -72,7 +72,7 @@
      * @throws IOException if the name is not a valid DNSName subjectAltName
      */
     public DNSName(String name) throws IOException {
-        if (name == null || name.length() == 0)
+        if (name == null || name.isEmpty())
             throw new IOException("DNSName must not be null or empty");
         if (name.contains(" "))
             throw new IOException("DNSName with blank components is not permitted");
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/x509/IPAddressName.java
--- a/src/java.base/share/classes/sun/security/x509/IPAddressName.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/x509/IPAddressName.java	Thu Dec 13 11:51:06 2018 -0800
@@ -125,7 +125,7 @@
      */
     public IPAddressName(String name) throws IOException {
 
-        if (name == null || name.length() == 0) {
+        if (name == null || name.isEmpty()) {
             throw new IOException("IPAddress cannot be null or empty");
         }
         if (name.charAt(name.length() - 1) == '/') {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/x509/RDN.java
--- a/src/java.base/share/classes/sun/security/x509/RDN.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/x509/RDN.java	Thu Dec 13 11:51:06 2018 -0800
@@ -121,7 +121,7 @@
                  * Plus sign is a separator
                  */
                 String avaString = name.substring(avaOffset, nextPlus);
-                if (avaString.length() == 0) {
+                if (avaString.isEmpty()) {
                     throw new IOException("empty AVA in RDN \"" + name + "\"");
                 }
 
@@ -141,7 +141,7 @@
 
         // parse last or only AVA
         String avaString = name.substring(avaOffset);
-        if (avaString.length() == 0) {
+        if (avaString.isEmpty()) {
             throw new IOException("empty AVA in RDN \"" + name + "\"");
         }
         AVA ava = new AVA(new StringReader(avaString), keywordMap);
@@ -199,7 +199,7 @@
                  * Plus sign is a separator
                  */
                 String avaString = name.substring(avaOffset, nextPlus);
-                if (avaString.length() == 0) {
+                if (avaString.isEmpty()) {
                     throw new IOException("empty AVA in RDN \"" + name + "\"");
                 }
 
@@ -217,7 +217,7 @@
 
         // parse last or only AVA
         String avaString = name.substring(avaOffset);
-        if (avaString.length() == 0) {
+        if (avaString.isEmpty()) {
             throw new IOException("empty AVA in RDN \"" + name + "\"");
         }
         AVA ava = new AVA(new StringReader(avaString), AVA.RFC2253, keywordMap);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/x509/RFC822Name.java
--- a/src/java.base/share/classes/sun/security/x509/RFC822Name.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/x509/RFC822Name.java	Thu Dec 13 11:51:06 2018 -0800
@@ -79,12 +79,12 @@
      * @throws IOException if name is not valid
      */
     public void parseName(String name) throws IOException {
-        if (name == null || name.length() == 0) {
+        if (name == null || name.isEmpty()) {
             throw new IOException("RFC822Name may not be null or empty");
         }
         // See if domain is a valid domain name
         String domain = name.substring(name.indexOf('@')+1);
-        if (domain.length() == 0) {
+        if (domain.isEmpty()) {
             throw new IOException("RFC822Name may not end with @");
         } else {
             //An RFC822 NameConstraint could start with a ., although
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/x509/X500Name.java
--- a/src/java.base/share/classes/sun/security/x509/X500Name.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/x509/X500Name.java	Thu Dec 13 11:51:06 2018 -0800
@@ -865,7 +865,7 @@
      */
     private void parseDN(String input, Map<String, String> keywordMap)
         throws IOException {
-        if (input == null || input.length() == 0) {
+        if (input == null || input.isEmpty()) {
             names = new RDN[0];
             return;
         }
@@ -937,7 +937,7 @@
     }
 
     private void parseRFC2253DN(String dnString) throws IOException {
-        if (dnString.length() == 0) {
+        if (dnString.isEmpty()) {
             names = new RDN[0];
             return;
          }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/x509/X509CRLImpl.java
--- a/src/java.base/share/classes/sun/security/x509/X509CRLImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/x509/X509CRLImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -370,7 +370,7 @@
             throw new CRLException("Uninitialized CRL");
         }
         Signature   sigVerf = null;
-        if (sigProvider.length() == 0) {
+        if (sigProvider.isEmpty()) {
             sigVerf = Signature.getInstance(sigAlgId.getName());
         } else {
             sigVerf = Signature.getInstance(sigAlgId.getName(), sigProvider);
@@ -495,7 +495,7 @@
             if (readOnly)
                 throw new CRLException("cannot over-write existing CRL");
             Signature sigEngine = null;
-            if ((provider == null) || (provider.length() == 0))
+            if (provider == null || provider.isEmpty())
                 sigEngine = Signature.getInstance(algorithm);
             else
                 sigEngine = Signature.getInstance(algorithm, provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/security/x509/X509CertImpl.java
--- a/src/java.base/share/classes/sun/security/x509/X509CertImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/security/x509/X509CertImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -429,7 +429,7 @@
         }
         // Verify the signature ...
         Signature sigVerf = null;
-        if (sigProvider.length() == 0) {
+        if (sigProvider.isEmpty()) {
             sigVerf = Signature.getInstance(algId.getName());
         } else {
             sigVerf = Signature.getInstance(algId.getName(), sigProvider);
@@ -598,7 +598,7 @@
                 throw new CertificateEncodingException(
                               "cannot over-write existing certificate");
             Signature sigEngine = null;
-            if ((provider == null) || (provider.length() == 0))
+            if (provider == null || provider.isEmpty())
                 sigEngine = Signature.getInstance(algorithm);
             else
                 sigEngine = Signature.getInstance(algorithm, provider);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/util/locale/InternalLocaleBuilder.java
--- a/src/java.base/share/classes/sun/util/locale/InternalLocaleBuilder.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/util/locale/InternalLocaleBuilder.java	Thu Dec 13 11:51:06 2018 -0800
@@ -331,7 +331,7 @@
                 done.add(key);
             }
         }
-        if (privateuse != null && privateuse.length() > 0) {
+        if (privateuse != null && !privateuse.isEmpty()) {
             // privateuse string contains prefix, e.g. "x-abc-def"
             if (extensions == null) {
                 extensions = new HashMap<>(1);
@@ -406,19 +406,19 @@
         // Validate base locale fields before updating internal state.
         // LocaleExtensions always store validated/canonicalized values,
         // so no checks are necessary.
-        if (language.length() > 0 && !LanguageTag.isLanguage(language)) {
+        if (!language.isEmpty() && !LanguageTag.isLanguage(language)) {
             throw new LocaleSyntaxException("Ill-formed language: " + language);
         }
 
-        if (script.length() > 0 && !LanguageTag.isScript(script)) {
+        if (!script.isEmpty() && !LanguageTag.isScript(script)) {
             throw new LocaleSyntaxException("Ill-formed script: " + script);
         }
 
-        if (region.length() > 0 && !LanguageTag.isRegion(region)) {
+        if (!region.isEmpty() && !LanguageTag.isRegion(region)) {
             throw new LocaleSyntaxException("Ill-formed region: " + region);
         }
 
-        if (variant.length() > 0) {
+        if (!variant.isEmpty()) {
             int errIdx = checkVariants(variant, BaseLocale.SEP);
             if (errIdx != -1) {
                 throw new LocaleSyntaxException("Ill-formed variant: " + variant, errIdx);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/util/locale/LanguageTag.java
--- a/src/java.base/share/classes/sun/util/locale/LanguageTag.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/util/locale/LanguageTag.java	Thu Dec 13 11:51:06 2018 -0800
@@ -212,7 +212,7 @@
         if (!itr.isDone() && !sts.isError()) {
             String s = itr.current();
             sts.errorIndex = itr.currentStart();
-            if (s.length() == 0) {
+            if (s.isEmpty()) {
                 sts.errorMsg = "Empty subtag";
             } else {
                 sts.errorMsg = "Invalid subtag: " + s;
@@ -454,7 +454,7 @@
             variant = "";
         }
 
-        if (variant.length() > 0) {
+        if (!variant.isEmpty()) {
             List<String> variants = null;
             StringTokenIterator varitr = new StringTokenIterator(variant, BaseLocale.SEP);
             while (!varitr.isDone()) {
@@ -527,7 +527,7 @@
             tag.privateuse = privateuse;
         }
 
-        if (tag.language.length() == 0 && (hasSubtag || privateuse == null)) {
+        if (tag.language.isEmpty() && (hasSubtag || privateuse == null)) {
             // use lang "und" when 1) no language is available AND
             // 2) any of other subtags other than private use are available or
             // no private use tag is available
@@ -712,18 +712,18 @@
     public String toString() {
         StringBuilder sb = new StringBuilder();
 
-        if (language.length() > 0) {
+        if (!language.isEmpty()) {
             sb.append(language);
 
             for (String extlang : extlangs) {
                 sb.append(SEP).append(extlang);
             }
 
-            if (script.length() > 0) {
+            if (!script.isEmpty()) {
                 sb.append(SEP).append(script);
             }
 
-            if (region.length() > 0) {
+            if (!region.isEmpty()) {
                 sb.append(SEP).append(region);
             }
 
@@ -735,7 +735,7 @@
                 sb.append(SEP).append(extension);
             }
         }
-        if (privateuse.length() > 0) {
+        if (!privateuse.isEmpty()) {
             if (sb.length() > 0) {
                 sb.append(SEP);
             }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/util/locale/LocaleMatcher.java
--- a/src/java.base/share/classes/sun/util/locale/LocaleMatcher.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/util/locale/LocaleMatcher.java	Thu Dec 13 11:51:06 2018 -0800
@@ -402,7 +402,7 @@
             }
 
             String rangeForRegex = range.replace("*", "\\p{Alnum}*");
-            while (rangeForRegex.length() > 0) {
+            while (!rangeForRegex.isEmpty()) {
                 for (String tag : tags) {
                     // change to lowercase for case-insensitive matching
                     String lowerCaseTag = tag.toLowerCase(Locale.ROOT);
@@ -437,7 +437,7 @@
             }
 
             String rangeForRegex = range.replace("*", "\\p{Alnum}*");
-            while (rangeForRegex.length() > 0) {
+            while (!rangeForRegex.isEmpty()) {
                 if (tag.matches(rangeForRegex)) {
                     return true;
                 }
@@ -591,7 +591,7 @@
     private static String[] getEquivalentsForLanguage(String range) {
         String r = range;
 
-        while (r.length() > 0) {
+        while (!r.isEmpty()) {
             if (LocaleEquivalentMaps.singleEquivMap.containsKey(r)) {
                 String equiv = LocaleEquivalentMaps.singleEquivMap.get(r);
                 // Return immediately for performance if the first matching
@@ -680,7 +680,7 @@
             String r = range;
             boolean hasEquivalent = false;
 
-            while (r.length() > 0) {
+            while (!r.isEmpty()) {
                 if (keyMap.containsKey(r)) {
                     hasEquivalent = true;
                     List<String> equivalents = map.get(keyMap.get(r));
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/util/locale/LocaleUtils.java
--- a/src/java.base/share/classes/sun/util/locale/LocaleUtils.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/util/locale/LocaleUtils.java	Thu Dec 13 11:51:06 2018 -0800
@@ -207,7 +207,7 @@
     }
 
     static boolean isEmpty(String str) {
-        return str == null || str.length() == 0;
+        return str == null || str.isEmpty();
     }
 
     static boolean isEmpty(Set<?> set) {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/util/locale/UnicodeLocaleExtension.java
--- a/src/java.base/share/classes/sun/util/locale/UnicodeLocaleExtension.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/util/locale/UnicodeLocaleExtension.java	Thu Dec 13 11:51:06 2018 -0800
@@ -80,7 +80,7 @@
                 String value = keyword.getValue();
 
                 sj.add(key);
-                if (value.length() > 0) {
+                if (!value.isEmpty()) {
                     sj.add(value);
                 }
             }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/util/locale/provider/CalendarNameProviderImpl.java
--- a/src/java.base/share/classes/sun/util/locale/provider/CalendarNameProviderImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/util/locale/provider/CalendarNameProviderImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -117,7 +117,7 @@
                 }
                 name = strings[value];
                 // If name is empty in standalone, try its `format' style.
-                if (name.length() == 0
+                if (name.isEmpty()
                         && (style == SHORT_STANDALONE || style == LONG_STANDALONE
                             || style == NARROW_STANDALONE)) {
                     name = getDisplayName(calendarType, field, value,
@@ -183,7 +183,7 @@
                             String name = strings[i];
                             // Ignore any empty string (some standalone month names
                             // are not defined)
-                            if (name.length() == 0) {
+                            if (name.isEmpty()) {
                                 continue;
                             }
                             map.put(name, base + i);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/util/locale/provider/JRELocaleProviderAdapter.java
--- a/src/java.base/share/classes/sun/util/locale/provider/JRELocaleProviderAdapter.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/util/locale/provider/JRELocaleProviderAdapter.java	Thu Dec 13 11:51:06 2018 -0800
@@ -503,7 +503,7 @@
          */
         String supportedLocaleString = createSupportedLocaleString("AvailableLocales");
 
-        if (supportedLocaleString.length() == 0) {
+        if (supportedLocaleString.isEmpty()) {
             throw new InternalError("No available locales for JRE");
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/share/classes/sun/util/locale/provider/LocaleProviderAdapter.java
--- a/src/java.base/share/classes/sun/util/locale/provider/LocaleProviderAdapter.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/share/classes/sun/util/locale/provider/LocaleProviderAdapter.java	Thu Dec 13 11:51:06 2018 -0800
@@ -121,7 +121,7 @@
         List<Type> typeList = new ArrayList<>();
 
         // Check user specified adapter preference
-        if (order != null && order.length() != 0) {
+        if (order != null && !order.isEmpty()) {
             String[] types = order.split(",");
             for (String type : types) {
                 type = type.trim().toUpperCase(Locale.ROOT);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/unix/classes/java/io/UnixFileSystem.java
--- a/src/java.base/unix/classes/java/io/UnixFileSystem.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/unix/classes/java/io/UnixFileSystem.java	Thu Dec 13 11:51:06 2018 -0800
@@ -98,7 +98,7 @@
     }
 
     public int prefixLength(String pathname) {
-        if (pathname.length() == 0) return 0;
+        if (pathname.isEmpty()) return 0;
         return (pathname.charAt(0) == '/') ? 1 : 0;
     }
 
@@ -249,7 +249,7 @@
     public int getBooleanAttributes(File f) {
         int rv = getBooleanAttributes0(f);
         String name = f.getName();
-        boolean hidden = (name.length() > 0) && (name.charAt(0) == '.');
+        boolean hidden = !name.isEmpty() && name.charAt(0) == '.';
         return rv | (hidden ? BA_HIDDEN : 0);
     }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/unix/classes/jdk/internal/loader/FileURLMapper.java
--- a/src/java.base/unix/classes/jdk/internal/loader/FileURLMapper.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/unix/classes/jdk/internal/loader/FileURLMapper.java	Thu Dec 13 11:51:06 2018 -0800
@@ -59,9 +59,9 @@
             return path;
         }
         String host = url.getHost();
-        if (host == null || "".equals(host) || "localhost".equalsIgnoreCase (host)) {
+        if (host == null || host.isEmpty() || "localhost".equalsIgnoreCase(host)) {
             path = url.getFile();
-            path = ParseUtil.decode (path);
+            path = ParseUtil.decode(path);
         }
         return path;
     }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/unix/classes/sun/net/dns/ResolverConfigurationImpl.java
--- a/src/java.base/unix/classes/sun/net/dns/ResolverConfigurationImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/unix/classes/sun/net/dns/ResolverConfigurationImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -68,14 +68,14 @@
             String line;
             while ((line = in.readLine()) != null) {
                 int maxvalues = maxperkeyword;
-                if (line.length() == 0)
+                if (line.isEmpty())
                    continue;
                 if (line.charAt(0) == '#' || line.charAt(0) == ';')
                     continue;
                 if (!line.startsWith(keyword))
                     continue;
                 String value = line.substring(keyword.length());
-                if (value.length() == 0)
+                if (value.isEmpty())
                     continue;
                 if (value.charAt(0) != ' ' && value.charAt(0) != '\t')
                     continue;
@@ -181,7 +181,7 @@
         // LOCALDOMAIN has absolute priority on Solaris
 
         String localDomain = localDomain0();
-        if (localDomain != null && localDomain.length() > 0) {
+        if (localDomain != null && !localDomain.isEmpty()) {
             sl = new LinkedList<>();
             sl.add(localDomain);
             return sl;
@@ -211,7 +211,7 @@
 
         sl = new LinkedList<>();
         String domain = fallbackDomain0();
-        if (domain != null && domain.length() > 0) {
+        if (domain != null && !domain.isEmpty()) {
             sl.add(domain);
         }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/unix/classes/sun/net/sdp/SdpProvider.java
--- a/src/java.base/unix/classes/sun/net/sdp/SdpProvider.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/unix/classes/sun/net/sdp/SdpProvider.java	Thu Dec 13 11:51:06 2018 -0800
@@ -77,7 +77,7 @@
         String logfile = props.getProperty("com.sun.sdp.debug");
         if (logfile != null) {
             out = System.out;
-            if (logfile.length() > 0) {
+            if (!logfile.isEmpty()) {
                 try {
                     out = new PrintStream(logfile);
                 } catch (IOException ignore) { }
@@ -167,9 +167,9 @@
                 result[1] = all ? MAX_PORT : result[0];
             } else {
                 String low = s.substring(0, pos);
-                if (low.length() == 0) low = "*";
+                if (low.isEmpty()) low = "*";
                 String high = s.substring(pos+1);
-                if (high.length() == 0) high = "*";
+                if (high.isEmpty()) high = "*";
                 result[0] = low.equals("*") ? 0 : Integer.parseInt(low);
                 result[1] = high.equals("*") ? MAX_PORT : Integer.parseInt(high);
             }
@@ -199,7 +199,7 @@
                 String line = scanner.nextLine().trim();
 
                 // skip blank lines and comments
-                if (line.length() == 0 || line.charAt(0) == '#')
+                if (line.isEmpty() || line.charAt(0) == '#')
                     continue;
 
                 // must have 3 fields
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/unix/classes/sun/net/www/protocol/file/Handler.java
--- a/src/java.base/unix/classes/sun/net/www/protocol/file/Handler.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/unix/classes/sun/net/www/protocol/file/Handler.java	Thu Dec 13 11:51:06 2018 -0800
@@ -127,9 +127,9 @@
          */
         String s1 = u1.getHost();
         String s2 = u2.getHost();
-        if ("localhost".equalsIgnoreCase(s1) && ( s2 == null || "".equals(s2)))
+        if ("localhost".equalsIgnoreCase(s1) && (s2 == null || s2.isEmpty()))
             return true;
-        if ("localhost".equalsIgnoreCase(s2) && ( s1 == null || "".equals(s1)))
+        if ("localhost".equalsIgnoreCase(s2) && (s1 == null || s1.isEmpty()))
             return true;
         return super.hostsEqual(u1, u2);
     }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/unix/classes/sun/nio/ch/UnixAsynchronousSocketChannelImpl.java
--- a/src/java.base/unix/classes/sun/nio/ch/UnixAsynchronousSocketChannelImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/unix/classes/sun/nio/ch/UnixAsynchronousSocketChannelImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -49,8 +49,8 @@
     static {
         String propValue = GetPropertyAction.privilegedGetProperty(
             "sun.nio.ch.disableSynchronousRead", "false");
-        disableSynchronousRead = (propValue.length() == 0) ?
-            true : Boolean.valueOf(propValue);
+        disableSynchronousRead = propValue.isEmpty() ?
+            true : Boolean.parseBoolean(propValue);
     }
 
     private final Port port;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/unix/classes/sun/nio/fs/UnixFileSystem.java
--- a/src/java.base/unix/classes/sun/nio/fs/UnixFileSystem.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/unix/classes/sun/nio/fs/UnixFileSystem.java	Thu Dec 13 11:51:06 2018 -0800
@@ -58,8 +58,7 @@
         // default directory.
         String propValue = GetPropertyAction
                 .privilegedGetProperty("sun.nio.fs.chdirAllowed", "false");
-        boolean chdirAllowed = (propValue.length() == 0) ?
-            true : Boolean.valueOf(propValue);
+        boolean chdirAllowed = propValue.isEmpty() ? true : Boolean.parseBoolean(propValue);
         if (chdirAllowed) {
             this.needToResolveAgainstDefaultDirectory = true;
         } else {
@@ -269,7 +268,7 @@
             StringBuilder sb = new StringBuilder();
             sb.append(first);
             for (String segment: more) {
-                if (segment.length() > 0) {
+                if (!segment.isEmpty()) {
                     if (sb.length() > 0)
                         sb.append('/');
                     sb.append(segment);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/windows/classes/java/io/WinNTFileSystem.java
--- a/src/java.base/windows/classes/java/io/WinNTFileSystem.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/windows/classes/java/io/WinNTFileSystem.java	Thu Dec 13 11:51:06 2018 -0800
@@ -64,7 +64,7 @@
     }
 
     private String slashify(String p) {
-        if ((p.length() > 0) && (p.charAt(0) != slash)) return slash + p;
+        if (!p.isEmpty() && p.charAt(0) != slash) return slash + p;
         else return p;
     }
 
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/windows/classes/sun/net/www/protocol/file/Handler.java
--- a/src/java.base/windows/classes/sun/net/www/protocol/file/Handler.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/windows/classes/sun/net/www/protocol/file/Handler.java	Thu Dec 13 11:51:06 2018 -0800
@@ -145,9 +145,9 @@
          */
         String s1 = u1.getHost();
         String s2 = u2.getHost();
-        if ("localhost".equalsIgnoreCase(s1) && ( s2 == null || "".equals(s2)))
+        if ("localhost".equalsIgnoreCase(s1) && (s2 == null || s2.isEmpty()))
             return true;
-        if ("localhost".equalsIgnoreCase(s2) && ( s1 == null || "".equals(s1)))
+        if ("localhost".equalsIgnoreCase(s2) && (s1 == null || s1.isEmpty()))
             return true;
         return super.hostsEqual(u1, u2);
     }
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/windows/classes/sun/nio/ch/FileDispatcherImpl.java
--- a/src/java.base/windows/classes/sun/nio/ch/FileDispatcherImpl.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/windows/classes/sun/nio/ch/FileDispatcherImpl.java	Thu Dec 13 11:51:06 2018 -0800
@@ -141,14 +141,8 @@
 
     static boolean isFastFileTransferRequested() {
         String fileTransferProp = GetPropertyAction
-                .privilegedGetProperty("jdk.nio.enableFastFileTransfer");
-        boolean enable;
-        if ("".equals(fileTransferProp)) {
-            enable = true;
-        } else {
-            enable = Boolean.parseBoolean(fileTransferProp);
-        }
-        return enable;
+                .privilegedGetProperty("jdk.nio.enableFastFileTransfer", "false");
+        return fileTransferProp.isEmpty() ? true : Boolean.parseBoolean(fileTransferProp);
     }
 
     static {
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/windows/classes/sun/nio/fs/WindowsFileAttributes.java
--- a/src/java.base/windows/classes/sun/nio/fs/WindowsFileAttributes.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/windows/classes/sun/nio/fs/WindowsFileAttributes.java	Thu Dec 13 11:51:06 2018 -0800
@@ -116,8 +116,7 @@
     static {
         String propValue = GetPropertyAction.privilegedGetProperty(
             "sun.nio.fs.ensureAccurateMetadata", "false");
-        ensureAccurateMetadata = (propValue.length() == 0) ?
-            true : Boolean.valueOf(propValue);
+        ensureAccurateMetadata = propValue.isEmpty() ? true : Boolean.parseBoolean(propValue);
     }
 
     // attributes
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/windows/classes/sun/nio/fs/WindowsFileStore.java
--- a/src/java.base/windows/classes/sun/nio/fs/WindowsFileStore.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/windows/classes/sun/nio/fs/WindowsFileStore.java	Thu Dec 13 11:51:06 2018 -0800
@@ -52,7 +52,7 @@
 
         // file store "display name" is the volume name if available
         String vol = volInfo.volumeName();
-        if (vol.length() > 0) {
+        if (!vol.isEmpty()) {
             this.displayName = vol;
         } else {
             // TBD - should we map all types? Does this need to be localized?
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/windows/classes/sun/nio/fs/WindowsFileSystem.java
--- a/src/java.base/windows/classes/sun/nio/fs/WindowsFileSystem.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/windows/classes/sun/nio/fs/WindowsFileSystem.java	Thu Dec 13 11:51:06 2018 -0800
@@ -218,7 +218,7 @@
             StringBuilder sb = new StringBuilder();
             sb.append(first);
             for (String segment: more) {
-                if (segment.length() > 0) {
+                if (!segment.isEmpty()) {
                     if (sb.length() > 0)
                         sb.append('\\');
                     sb.append(segment);
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/windows/classes/sun/nio/fs/WindowsLinkSupport.java
--- a/src/java.base/windows/classes/sun/nio/fs/WindowsLinkSupport.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/windows/classes/sun/nio/fs/WindowsLinkSupport.java	Thu Dec 13 11:51:06 2018 -0800
@@ -329,7 +329,7 @@
 
             // remove special prefix
             String target = stripPrefix(new String(name));
-            if (target.length() == 0) {
+            if (target.isEmpty()) {
                 throw new IOException("Symbolic link target is invalid");
             }
             return target;
diff -r fd6de53a0d6e -r b94283cb226b src/java.base/windows/classes/sun/nio/fs/WindowsPath.java
--- a/src/java.base/windows/classes/sun/nio/fs/WindowsPath.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/java.base/windows/classes/sun/nio/fs/WindowsPath.java	Thu Dec 13 11:51:06 2018 -0800
@@ -243,7 +243,7 @@
             // relative to default directory
             String remaining = path.substring(root.length());
             String defaultDirectory = getFileSystem().defaultDirectory();
-            if (remaining.length() == 0) {
+            if (remaining.isEmpty()) {
                 return defaultDirectory;
             } else if (defaultDirectory.endsWith("\\")) {
                  return defaultDirectory + remaining;
@@ -299,7 +299,7 @@
     // -- Path operations --
 
     private boolean isEmpty() {
-        return path.length() == 0;
+        return path.isEmpty();
     }
 
     private WindowsPath emptyPath() {
@@ -340,7 +340,7 @@
 
     @Override
     public WindowsPath getRoot() {
-        if (root.length() == 0)
+        if (root.isEmpty())
             return null;
         return new WindowsPath(getFileSystem(), type, root, root);
     }
@@ -556,7 +556,7 @@
 
         // corner case - all names removed
         if (remaining == 0) {
-            return (root.length() == 0) ? emptyPath() : getRoot();
+            return root.isEmpty() ? emptyPath() : getRoot();
         }
 
         // re-constitute the path from the remaining names.
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/Recording.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/Recording.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/Recording.java	Thu Dec 13 11:51:06 2018 -0800
@@ -54,7 +54,7 @@
  *   System.gc();
  *   Thread.sleep(5000);
  *   r.stop();
- *   r.copyTo(Files.createTempFile("my-recording", ".jfr"));
+ *   r.dump(Files.createTempFile("my-recording", ".jfr"));
  * </code>
  * </pre>
  *
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/consumer/package-info.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/consumer/package-info.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/consumer/package-info.java	Thu Dec 13 11:51:06 2018 -0800
@@ -29,40 +29,27 @@
  * In the following example, the program prints a histogram of all method samples in a recording.
  * <pre>
  * <code>
- *   public static void main(String[] args) {
- *     if (args.length != 0) {
- *       System.out.println("Must specify recording file.");
- *       return;
+ * public static void main(String[] args) throws IOException {
+ *     if (args.length != 1) {
+ *         System.err.println("Must specify a recording file.");
+ *         return;
  *     }
- *     try (RecordingFile f = new RecordingFile(Paths.get(args[0]))) {
- *       Map{@literal <}String, SimpleEntry{@literal <}String, Integer{@literal >}{@literal >} histogram = new HashMap{@literal <}{@literal >}();
- *       int total = 0;
- *       while (f.hasMoreEvents()) {
- *         RecordedEvent event = f.readEvent();
- *         if (event.getEventType().getName().equals("jdk.ExecutionSample")) {
- *           RecordedStackTrace s = event.getStackTrace();
- *           if (s != null) {
- *             RecordedFrame topFrame= s.getFrames().get(0);
- *             if (topFrame.isJavaFrame())  {
- *               RecordedMethod method = topFrame.getMethod();
- *               String methodName = method.getType().getName() + "#" + method.getName() + " " + method.getDescriptor();
- *               Entry entry = histogram.computeIfAbsent(methodName, u -{@literal >} new SimpleEntry{@literal <}String, Integer{@literal >}(methodName, 0));
- *               entry.setValue(entry.getValue() + 1);
- *               total++;
- *             }
- *           }
- *         }
- *       }
- *       List{@literal <}SimpleEntry{@literal <}String, Integer{@literal >}{@literal >} entries = new ArrayList{@literal <}{@literal >}(histogram.values());
- *       entries.sort((u, v) -{@literal >} v.getValue().compareTo(u.getValue()));
- *       for (SimpleEntry{@literal <}String, Integer{@literal >} c : entries) {
- *         System.out.printf("%2.0f%% %s\n", 100 * (float) c.getValue() / total, c.getKey());
- *       }
- *       System.out.println("\nSample count: " + total);
- *     } catch (IOException ioe) {
- *       System.out.println("Error reading file " + args[0] + ". " + ioe.getMessage());
- *     }
- *   }
+ *
+ *     RecordingFile.readAllEvents(Path.of(args[0])).stream()
+ *         .filter(e -> e.getEventType().getName().equals("jdk.ExecutionSample"))
+ *         .map(e -> e.getStackTrace())
+ *         .filter(s -> s != null)
+ *         .map(s -> s.getFrames().get(0))
+ *         .filter(f -> f.isJavaFrame())
+ *         .map(f -> f.getMethod())
+ *         .collect(
+ *             Collectors.groupingBy(m -> m.getType().getName() + "." + m.getName() + " " + m.getDescriptor(),
+ *             Collectors.counting()))
+ *         .entrySet()
+ *         .stream()
+ *         .sorted((a, b) -> b.getValue().compareTo(a.getValue()))
+ *         .forEach(e -> System.out.printf("%8d %s\n", e.getValue(), e.getKey()));
+ * }
  * </code>
  * </pre>
  * <p>
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/internal/JVM.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/JVM.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/JVM.java	Thu Dec 13 11:51:06 2018 -0800
@@ -516,4 +516,11 @@
      * @param emitAll emit all samples in old object queue
      */
     public native void emitOldObjectSamples(long cutoff, boolean emitAll);
+
+    /**
+     * Test if a chunk rotation is warranted.
+     *
+     * @return if it is time to perform a chunk rotation
+     */
+    public native boolean shouldRotateDisk();
 }
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/internal/MetadataHandler.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/MetadataHandler.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/MetadataHandler.java	Thu Dec 13 11:51:06 2018 -0800
@@ -100,7 +100,7 @@
 
     final Map<String, TypeElement> types = new LinkedHashMap<>(200);
     final Map<String, XmlType> xmlTypes = new HashMap<>(20);
-    final Map<String, AnnotationElement> xmlContentTypes = new HashMap<>(20);
+    final Map<String, List<AnnotationElement>> xmlContentTypes = new HashMap<>(20);
     final List<String> relations = new ArrayList<>();
     long eventTypeId = 255;
     long structTypeId = 33;
@@ -148,11 +148,8 @@
             break;
         case "XmlContentType":
             String name = attributes.getValue("name");
-            String type = attributes.getValue("annotationType");
-            String value = attributes.getValue("annotationValue");
-            Class<? extends Annotation> annotationType = createAnnotationClass(type);
-            AnnotationElement ae = value == null ? new AnnotationElement(annotationType) : new AnnotationElement(annotationType, value);
-            xmlContentTypes.put(name, ae);
+            String annotation = attributes.getValue("annotation");
+            xmlContentTypes.put(name, createAnnotationElements(annotation));
             break;
         case "Relation":
             String n = attributes.getValue("name");
@@ -161,6 +158,27 @@
         }
     }
 
+    private List<AnnotationElement> createAnnotationElements(String annotation) throws InternalError {
+        String[] annotations = annotation.split(",");
+        List<AnnotationElement> annotationElements = new ArrayList<>();
+        for (String a : annotations) {
+            a = a.trim();
+            int leftParenthesis = a.indexOf("(");
+            if (leftParenthesis == -1) {
+                annotationElements.add(new AnnotationElement(createAnnotationClass(a)));
+            } else {
+                int rightParenthesis = a.lastIndexOf(")");
+                if (rightParenthesis == -1) {
+                    throw new InternalError("Expected closing parenthesis for 'XMLContentType'");
+                }
+                String value = a.substring(leftParenthesis + 1, rightParenthesis);
+                String type = a.substring(0, leftParenthesis);
+                annotationElements.add(new AnnotationElement(createAnnotationClass(type), value));
+            }
+        }
+        return annotationElements;
+    }
+
     @SuppressWarnings("unchecked")
     private Class<? extends Annotation> createAnnotationClass(String type) {
         try {
@@ -255,7 +273,7 @@
                     aes.add(new AnnotationElement(Unsigned.class));
                 }
                 if (f.contentType != null) {
-                    aes.add(Objects.requireNonNull(xmlContentTypes.get(f.contentType)));
+                    aes.addAll(Objects.requireNonNull(xmlContentTypes.get(f.contentType)));
                 }
                 if (f.relation != null) {
                     aes.add(Objects.requireNonNull(relationMap.get(f.relation)));
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/internal/PlatformRecorder.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/PlatformRecorder.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/PlatformRecorder.java	Thu Dec 13 11:51:06 2018 -0800
@@ -427,19 +427,13 @@
     }
 
     private void periodicTask() {
+        if (!jvm.hasNativeJFR()) {
+            return;
+        }
         while (true) {
             synchronized (this) {
-                if (!jvm.hasNativeJFR()) {
-                    return;
-                }
-                if (currentChunk != null) {
-                    try {
-                        if (SecuritySupport.getFileSize(currentChunk.getUnfishedFile()) > Options.getMaxChunkSize()) {
-                            rotateDisk();
-                        }
-                    } catch (IOException e) {
-                        Logger.log(JFR_SYSTEM, WARN, "Could not check file size to determine chunk rotation");
-                    }
+                if (jvm.shouldRotateDisk()) {
+                    rotateDisk();
                 }
             }
             long minDelta = RequestEngine.doPeriodic();
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/internal/PlatformRecording.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/PlatformRecording.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/PlatformRecording.java	Thu Dec 13 11:51:06 2018 -0800
@@ -123,7 +123,7 @@
                     options.add("maxage=" + Utils.formatTimespan(maxAge, ""));
                 }
                 if (maxSize != 0) {
-                    options.add("maxsize=" + Utils.formatBytes(maxSize, ""));
+                    options.add("maxsize=" + Utils.formatBytesCompact(maxSize));
                 }
                 if (dumpOnExit) {
                     options.add("dumponexit=true");
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/internal/Utils.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/Utils.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/Utils.java	Thu Dec 13 11:51:06 2018 -0800
@@ -103,18 +103,53 @@
         }
     }
 
-    public static String formatBytes(long bytes, String separation) {
-        if (bytes == 1) {
-            return "1 byte";
+    // Tjis method can't handle Long.MIN_VALUE because absolute value is negative
+    private static String formatDataAmount(String formatter, long amount) {
+        int exp = (int) (Math.log(Math.abs(amount)) / Math.log(1024));
+        char unitPrefix = "kMGTPE".charAt(exp - 1);
+        return String.format(formatter, amount / Math.pow(1024, exp), unitPrefix);
+    }
+
+    public static String formatBytesCompact(long bytes) {
+        if (bytes < 1024) {
+            return String.valueOf(bytes);
         }
-        if (bytes < 1024) {
+        return formatDataAmount("%.1f%cB", bytes);
+    }
+
+    public static String formatBits(long bits) {
+        if (bits == 1 || bits == -1) {
+            return bits + " bit";
+        }
+        if (bits < 1024 && bits > -1024) {
+            return bits + " bits";
+        }
+        return formatDataAmount("%.1f %cbit", bits);
+    }
+
+    public static String formatBytes(long bytes) {
+        if (bytes == 1 || bytes == -1) {
+            return bytes + " byte";
+        }
+        if (bytes < 1024 && bytes > -1024) {
             return bytes + " bytes";
         }
-        int exp = (int) (Math.log(bytes) / Math.log(1024));
-        char bytePrefix = "kMGTPE".charAt(exp - 1);
-        return String.format("%.1f%s%cB", bytes / Math.pow(1024, exp), separation, bytePrefix);
+        return formatDataAmount("%.1f %cB", bytes);
     }
 
+    public static String formatBytesPerSecond(long bytes) {
+        if (bytes < 1024 && bytes > -1024) {
+            return bytes + " byte/s";
+        }
+        return formatDataAmount("%.1f %cB/s", bytes);
+    }
+
+    public static String formatBitsPerSecond(long bits) {
+        if (bits < 1024 && bits > -1024) {
+            return bits + " bps";
+        }
+        return formatDataAmount("%.1f %cbps", bits);
+    }
     public static String formatTimespan(Duration dValue, String separation) {
         if (dValue == null) {
             return "0";
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/AbstractDCmd.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/AbstractDCmd.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/AbstractDCmd.java	Thu Dec 13 11:51:06 2018 -0800
@@ -109,7 +109,7 @@
             try {
                 print(" ");
                 long bytes = SecuritySupport.getFileSize(file);
-                printBytes(bytes, " ");
+                printBytes(bytes);
             } catch (IOException e) {
                 // Ignore, not essential
             }
@@ -152,8 +152,8 @@
         println();
     }
 
-    protected final void printBytes(long bytes, String separation) {
-        print(Utils.formatBytes(bytes, separation));
+    protected final void printBytes(long bytes) {
+        print(Utils.formatBytes(bytes));
     }
 
     protected final void printTimespan(Duration timespan, String separator) {
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/DCmdCheck.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/DCmdCheck.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/DCmdCheck.java	Thu Dec 13 11:51:06 2018 -0800
@@ -39,6 +39,7 @@
 import jdk.jfr.internal.LogLevel;
 import jdk.jfr.internal.LogTag;
 import jdk.jfr.internal.Logger;
+import jdk.jfr.internal.Utils;
 
 /**
  * JFR.check - invoked from native
@@ -117,7 +118,7 @@
         long maxSize = recording.getMaxSize();
         if (maxSize != 0) {
             print(" maxsize=");
-            printBytes(maxSize, "");
+            print(Utils.formatBytesCompact(maxSize));
         }
         Duration maxAge = recording.getMaxAge();
         if (maxAge != null) {
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/DCmdConfigure.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/DCmdConfigure.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/dcmd/DCmdConfigure.java	Thu Dec 13 11:51:06 2018 -0800
@@ -193,25 +193,25 @@
 
     private void printGlobalBufferSize() {
         print("Global buffer size: ");
-        printBytes(Options.getGlobalBufferSize(), " ");
+        printBytes(Options.getGlobalBufferSize());
         println();
     }
 
     private void printThreadBufferSize() {
         print("Thread buffer size: ");
-        printBytes(Options.getThreadBufferSize(), " ");
+        printBytes(Options.getThreadBufferSize());
         println();
     }
 
     private void printMemorySize() {
         print("Memory size: ");
-        printBytes(Options.getMemorySize(), " ");
+        printBytes(Options.getMemorySize());
         println();
     }
 
     private void printMaxChunkSize() {
         print("Max chunk size: ");
-        printBytes(Options.getMaxChunkSize(), " ");
+        printBytes(Options.getMaxChunkSize());
         println();
     }
 }
diff -r fd6de53a0d6e -r b94283cb226b src/jdk.jfr/share/classes/jdk/jfr/internal/tool/PrettyWriter.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/tool/PrettyWriter.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/tool/PrettyWriter.java	Thu Dec 13 11:51:06 2018 -0800
@@ -315,11 +315,7 @@
             printArray((Object[]) value);
             return;
         }
-        if (field.getContentType() != null) {
-            if (printFormatted(field, value)) {
-                return;
-            }
-        }
+
         if (value instanceof Double) {
             Double d = (Double) value;
             if (Double.isNaN(d) || d == Double.NEGATIVE_INFINITY) {
@@ -349,6 +345,12 @@
             }
         }
 
+        if (field.getContentType() != null) {
+            if (printFormatted(field, value)) {
+                return;
+            }
+        }
+
         String text = String.valueOf(value);
         if (value instanceof String) {
             text = "\"" + text + "\"";
@@ -472,7 +474,7 @@
     private boolean printFormatted(ValueDescriptor field, Object value) {
         if (value instanceof Duration) {
             Duration d = (Duration) value;
-            if (d.getSeconds() == Long.MIN_VALUE)  {
+            if (d.getSeconds() == Long.MIN_VALUE && d.getNano() == 0)  {
                 println("N/A");
                 return true;
             }
@@ -513,12 +515,26 @@
         if (dataAmount != null) {
             if (value instanceof Number) {
                 Number n = (Number) value;
-                String bytes = Utils.formatBytes(n.longValue(), " ");
+                long amount = n.longValue();
                 if (field.getAnnotation(Frequency.class) != null) {
-                    bytes += "/s";
+                    if (dataAmount.value().equals(DataAmount.BYTES)) {
+                        println(Utils.formatBytesPerSecond(amount));
+                        return true;
+                    }
+                    if (dataAmount.value().equals(DataAmount.BITS)) {
+                        println(Utils.formatBitsPerSecond(amount));
+                        return true;
+                    }
+                } else {
+                    if (dataAmount.value().equals(DataAmount.BYTES)) {
+                        println(Utils.formatBytes(amount));
+                        return true;
+                    }
+                    if (dataAmount.value().equals(DataAmount.BITS)) {
+                        println(Utils.formatBits(amount));
+                        return true;
+                    }
                 }
-                println(bytes);
-                return true;
             }
         }
         MemoryAddress memoryAddress = field.getAnnotation(MemoryAddress.class);
@@ -529,6 +545,14 @@
                 return true;
             }
         }
+        Frequency frequency = field.getAnnotation(Frequency.class);
+        if (frequency != null) {
+            if (value instanceof Number) {
+                println(value + " Hz");
+                return true;
+            }
+        }
+
         return false;
     }
 
diff -r fd6de53a0d6e -r b94283cb226b test/hotspot/jtreg/runtime/Safepoint/TestAbortOnVMOperationTimeout.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/runtime/Safepoint/TestAbortOnVMOperationTimeout.java	Thu Dec 13 11:51:06 2018 -0800
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import jdk.test.lib.*;
+import jdk.test.lib.process.*;
+
+/*
+ * @test TestAbortOnVMOperationTimeout
+ * @bug 8181143
+ * @summary Check abort on VM timeout is working
+ * @library /test/lib
+ * @modules java.base/jdk.internal.misc
+ *          java.management
+ */
+
+public class TestAbortOnVMOperationTimeout {
+
+    public static void main(String[] args) throws Exception {
+        if (args.length > 0) {
+            Object[] arr = new Object[10_000_000];
+            for (int i = 0; i < arr.length; i++) {
+               arr[i] = new Object();
+            }
+            return;
+        }
+
+        // These should definitely pass: more than a minute is enough for Serial to act.
+        // The values are deliberately non-round to trip off periodic task granularity.
+        for (int delay : new int[]{63423, 12388131}) {
+            testWith(delay, true);
+        }
+
+        // These should fail: Serial is not very fast. Traversing 10M objects in 5 ms
+        // means less than 0.5 ns per object, which is not doable.
+        for (int delay : new int[]{0, 1, 5}) {
+            testWith(delay, false);
+        }
+    }
+
+    public static void testWith(int delay, boolean shouldPass) throws Exception {
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
+                "-XX:+UnlockDiagnosticVMOptions",
+                "-XX:+AbortVMOnVMOperationTimeout",
+                "-XX:AbortVMOnVMOperationTimeoutDelay=" + delay,
+                "-Xmx256m",
+                "-XX:+UseSerialGC",
+                "-XX:-CreateCoredumpOnCrash",
+                "TestAbortOnVMOperationTimeout",
+                "foo"
+        );
+
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+        if (shouldPass) {
+            output.shouldHaveExitValue(0);
+        } else {
+            output.shouldMatch("VM operation took too long");
+            output.shouldNotHaveExitValue(0);
+        }
+    }
+}
+
diff -r fd6de53a0d6e -r b94283cb226b test/jdk/java/lang/constant/ClassDescTest.java
--- a/test/jdk/java/lang/constant/ClassDescTest.java	Thu Dec 13 11:47:35 2018 -0800
+++ b/test/jdk/java/lang/constant/ClassDescTest.java	Thu Dec 13 11:51:06 2018 -0800
@@ -244,6 +244,29 @@
             testBadNestedClasses(ClassDesc.ofDescriptor(p.descriptor), "any");
             testBadNestedClasses(ClassDesc.ofDescriptor(p.descriptor), "any", "other");
         }
+
+        ClassDesc stringDesc = ClassDesc.ofDescriptor("Ljava/lang/String;");
+        ClassDesc stringArrDesc = stringDesc.arrayType(255);
+        try {
+            ClassDesc arrGreaterThan255 = stringArrDesc.arrayType();
+            fail("can't create an array type descriptor with more than 255 dimensions");
+        } catch (IllegalStateException e) {
+            // good
+        }
+        String descWith255ArrayDims = new String(new char[255]).replace('\0', '[');
+        try {
+            ClassDesc arrGreaterThan255 = ClassDesc.ofDescriptor(descWith255ArrayDims + "[Ljava/lang/String;");
+            fail("can't create an array type descriptor with more than 255 dimensions");
+        } catch (IllegalArgumentException e) {
+            // good
+        }
+        try {
+            ClassDesc arrWith255Dims = ClassDesc.ofDescriptor(descWith255ArrayDims + "Ljava/lang/String;");
+            arrWith255Dims.arrayType(1);
+            fail("can't create an array type descriptor with more than 255 dimensions");
+        } catch (IllegalArgumentException e) {
+            // good
+        }
     }
 
     private void testBadNestedClasses(ClassDesc cr, String firstNestedName, String... moreNestedNames) {
diff -r fd6de53a0d6e -r b94283cb226b test/jdk/jdk/jfr/api/metadata/annotations/TestFormatMissingValue.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/jdk/jfr/api/metadata/annotations/TestFormatMissingValue.java	Thu Dec 13 11:51:06 2018 -0800
@@ -0,0 +1,125 @@
+/*
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.jfr.api.metadata.annotations;
+
+import jdk.jfr.DataAmount;
+import jdk.jfr.Event;
+import jdk.jfr.Frequency;
+import jdk.jfr.Recording;
+import jdk.jfr.StackTrace;
+import jdk.jfr.consumer.RecordedEvent;
+import jdk.test.lib.Asserts;
+import jdk.test.lib.jfr.Events;
+
+/**
+ * @test
+ * @key jfr
+ * @summary Check that event values are properly formatted and sanity check
+ *              that extreme values don't throws exceptions
+ * @requires vm.hasJFR
+ * @library /test/lib
+ * @run main/othervm jdk.jfr.api.metadata.annotations.TestFormatMissingValue
+ */
+public class TestFormatMissingValue {
+
+    @StackTrace(false)
+    static class MultiContentTypeEvent extends Event {
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        long a = Long.MIN_VALUE;
+
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        long b = Long.MAX_VALUE;
+
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        int c = Integer.MIN_VALUE;
+
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        int d = Integer.MAX_VALUE;
+
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        double e = Double.NEGATIVE_INFINITY;
+
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        double f = Double.POSITIVE_INFINITY;
+
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        double g = Double.NaN;
+
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        float h = Float.NEGATIVE_INFINITY;
+
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        float i = Float.POSITIVE_INFINITY;
+
+        @DataAmount(DataAmount.BYTES)
+        @Frequency
+        float j = Float.NaN;
+    }
+
+    public static void main(String[] args) throws Exception {
+        try (Recording r = new Recording()) {
+            r.start();
+            MultiContentTypeEvent m = new MultiContentTypeEvent();
+            m.commit();
+            r.stop();
+            for (RecordedEvent e : Events.fromRecording(r)) {
+                String t = e.toString();
+                assertContains(t, "a = N/A");
+                assertContains(t, "c = N/A");
+                assertContains(t, "e = N/A");
+                assertContains(t, "g = N/A");
+                assertContains(t, "h = N/A");
+                assertContains(t, "j = N/A");
+
+                assertNotContains(t, "b = N/A");
+                assertNotContains(t, "d = N/A");
+                assertNotContains(t, "f = N/A");
+                assertNotContains(t, "i = N/A");
+            }
+        }
+    }
+
+    private static void assertContains(String t, String text) {
+        if (!t.contains(text)) {
+            Asserts.fail("Expected '" + t + "' to contain text '" + text + "'");
+        }
+    }
+
+    private static void assertNotContains(String t, String text) {
+        if (t.contains(text)) {
+            Asserts.fail("Found unexpected value '" + text + "'  in text '" + t + "'");
+        }
+    }
+}