Finite-state automata and regular expressions for Java. The package includes a DFA/NFA implementation with Unicode alphabet and support for all standard regular expression operations, like concatenation, union, intersection, complement, Kleene star.

Pure Java implementation of a traditional (non-POSIX) NFA regular expression engine. Its syntax can emulate many popular development tools, including awk, sed, emacs, perl and grep. [Open Source, LGPL]

Regular expression support that offers a superset of Perl5.6 regex syntax, compatibility with JDK 1.1). Includes documentation, examples, and demonstration applet. [Open Source, BSD-like]

A package that provides a mechanism for compiling and matching regular expressions in Java. Download, documentation and news.

A regular expression API for textual pattern matching based on the finite state automaton theory written in Java. It also offers set operations (union, intersection, difference, complement) for combination of automatons. [Open source, LGPL]

A set of text-processing classes that provide Perl5 compatible regular expressions, AWK-like regular expressions, glob expressions, and utility classes for performing substitutions, splits, and filtering filenames. This library is the open source succ...

Lightweight regular expressions pattern matcher. [Open Source, BSD-like]

Provides a package to perform Regular Expressions in Java. Documentation and download including source.

Applets reads simple regular expressions and builds a state machine that recognizes regular expression. Provided source code is appropriate for educational purposes.

Regular expressions are a useful programming tool. The fact that Java now natively supports them simplifies many programming tasks that used to require cumbersome code. A description of the new features on earthweb.com.