You didn't try very hard did you? Google "jakarta regexp".
You're in luck - it's open-source and free, so you can probably use it in your application.
Note, however, that Java has had regular expression capabilities for some years, now. If you are writing a new application, or modifying an application that uses a modern version of Java, you should probably prefer Java's own implementation to Jakarta's. Nothing wrong with Jakarta's, but why make it complicated?
If you have an existing application that uses Jakarta Regexp, then that's fine. Likewise, if you need to use a really old version of Java (e.g. 1.2), for some reason, then using Jakarta Regexp could make sense. [ January 14, 2008: Message edited by: Peter Chase ]
Betty Rubble? Well, I would go with Betty... but I'd be thinking of Wilma.