diff -r e10a1f7aaa13 -r 8bf9268df0e2 src/java.base/share/classes/java/util/regex/Pattern.java
--- a/src/java.base/share/classes/java/util/regex/Pattern.java	Thu Dec 13 16:14:07 2018 +0100
+++ b/src/java.base/share/classes/java/util/regex/Pattern.java	Thu Dec 13 15:31:05 2018 +0100
@@ -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);