Useful regex test site for java: http://www.ocpsoft.org/tutorials/regular-expressions/java-visual-regex-tester/ http://java-regex-tester.appspot.com/ Very good site(non-java): http://regexr.com/ Very good learning site: http://www.regular-expressions.info/ http://www.bearcave.com/software/antlr/antlr_examples.html