--- a/src/java.base/share/classes/sun/security/util/SignatureFileVerifier.java	Thu Dec 13 16:14:07 2018 +0100
+++ b/src/java.base/share/classes/sun/security/util/SignatureFileVerifier.java	Thu Dec 13 15:31:05 2018 +0100
@@ -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)";
         }