Index: src/main/java/java/util/regex/Matcher.java =================================================================== --- src/main/java/java/util/regex/Matcher.java (revision 495509) +++ src/main/java/java/util/regex/Matcher.java (working copy) @@ -508,6 +508,9 @@ * @com.intel.drl.spec_ref */ public Matcher usePattern(Pattern pat) { + if (pat == null) { + throw new IllegalArgumentException(Messages.getString("regex.1B")); + } int startIndex = matchResult.getPreviousMatchEnd(); int mode = matchResult.mode(); this.pat = pat; Index: src/main/java/org/apache/harmony/regex/internal/nls/messages.properties =================================================================== --- src/main/java/org/apache/harmony/regex/internal/nls/messages.properties (revision 495509) +++ src/main/java/org/apache/harmony/regex/internal/nls/messages.properties (working copy) @@ -41,3 +41,4 @@ regex.18=Invalid {0} escape sequence regex.19=Invalid octal escape sequence regex.1A=Illegal inline construct +regex.1B=Pattern cannot be null