--- a/src/java.base/share/classes/java/nio/Heap-X-Buffer.java.template	Thu Feb 28 10:04:27 2019 -0800
+++ b/src/java.base/share/classes/java/nio/Heap-X-Buffer.java.template	Thu Feb 28 12:05:59 2019 -0800
@@ -27,6 +27,8 @@
 
 package java.nio;
 
+import java.util.Objects;
+
 /**
 #if[rw]
  * A read/write Heap$Type$Buffer.
@@ -38,8 +40,6 @@
 #end[rw]
  */
 
-import java.util.Objects;
-
 class Heap$Type$Buffer$RW$
     extends {#if[ro]?Heap}$Type$Buffer
 {
@@ -112,19 +112,17 @@
                                         this.position() + offset);
     }
 
-#if[byte]
-    $Type$Buffer slice(int pos, int lim) {
-        assert (pos >= 0);
-        assert (pos <= lim);
-        int rem = lim - pos;
+    @Override
+    public $Type$Buffer slice(int index, int length) {
+        Objects.checkIndex(index, limit() + 1);
+        Objects.checkIndex(length, limit() - index + 1);
         return new Heap$Type$Buffer$RW$(hb,
                                         -1,
                                         0,
-                                        rem,
-                                        rem,
-                                        pos + offset);
+                                        length,
+                                        length,
+                                        index + offset);
     }
-#end[byte]
 
     public $Type$Buffer duplicate() {
         return new Heap$Type$Buffer$RW$(hb,