Simple Java Regular Expression Parser and Recognizer

This applet lets you enter a simple regular expression and tells you if strings match that regular expression. Currently, the regular expression language supports contatenation (ab), intesection (a+b), and repeat zero or more times (a*). '?' matches any symbol. '^' is the NULL symbol. Parenthesis are recommended. Spaces are treated like symbols. Source code is provided.

Sample regular expressions:

Source Code