Regexp is a 100% Pure Java Regular Expression package that was graciously donated to the Apache Software Foundation by Jonathan Locke. He originally wrote this software back in 1996 and it has stood up quite well to the test of time. It includes complete Javadoc documentation as well as a simple Applet for visual debugging and testing suite for compatibility.

The Jakarta-ORO Java classes are a set of text-processing Java classes that provide Perl5 compatible regular expressions, AWK-like regular expressions, glob expressions, and utility classes for performing substitutions, splits, filtering filenames, etc.