--- a/src/java.base/share/classes/java/text/PatternEntry.java	Thu Dec 13 16:14:07 2018 +0100
+++ b/src/java.base/share/classes/java/text/PatternEntry.java	Thu Dec 13 15:31:05 2018 +0100
@@ -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);
         }