A eclipse plugin to test regular expressions (regex). Full highlighting of regexp syntax. Tooltip with detailed description of regex items, etc... Very usefull. Project page has java-applet to test regexp online. (Regex implementation: java.util.regex.*)
javautilcmdline /javautil is a reusable Java library for common programming tasks, such as String, File, RegEx (Regular Expressions), Array manipulation, etc. The package also contains command line tools that mimic many Unix commands.