As any Perl developer will tell you, regular expressions are an extremely powerful addition to the programmer's problem-solving arsenal, so the inclusion of the java.util.regex API in Java 1.4 is definitely a Good Thing™. While there are countless web tutorials and examples on the API and regexes generally, what I was after was an actual tester, something quick-and-dirty I could simply type straight into and check how a real, live pattern would match against actual input.

Enter my humble regex tester; I originally created this as a standalone Swing application, but applet-ised it to enhance its world-wide-web appeal. The source is included in the jar file; do with it as you please.

• Could hardly be any easier to use:

  Enter some text to search over in the input text area, and provide a Java-style regex in the pattern field. (That's Java-style: although modelled on Perl regexes, there are some minor differences.)

  Optionally, you can specify Pattern modifier flags via the options checkboxes. These flags are described in the API documentation.

  If your pattern is legal (green), you'll be able to step through all matches by clicking the next match button. The reset button returns you to the start (before the first match).

• If your regex includes groups (in parentheses), the captured values will be shown for each match
• Initial values for the pattern and input fields can be specified via applet <param> elements; view the source of this page for an example.
• You'll need an appropriate 1.4 JRE installed and properly configured for your browser.(1) Oh, and make sure applets are enabled (duh).

Not Quite Right

• Can only traverse matches forwards.
• Obscure applet (browser/plugin?) bug: greyed-out components remain enabled.
• Damn horrible HTML hack to get the <object> tag to work with IE.