Regular Expressions are powerful but can be confusing at times. I regularly found myself working with scrapbook-pages to test my regular expressions (or working late-night shifts to fix problems in production :-( ). QuickREx was written to get around using scrapbook pages or working on the high-wire and to be able to play with regular expressions more easily.
QuickREx gives you a view in which you can enter test-texts and try regular expressions. The expressions are evaluated against the test-text on the fly, matches are highlighted and you can navigate between the matches. You can also navigate through groups within each match (if groups are defined in your regular expression).
Regular Expressions are edited either within the view or within a composition-dialog which offers the most useful building-blocks grouped in categories and accompanied by short explanations.
QuickREx also offers TAB-completion for regular expressions and conversion of regular expressions to Java-Strings (including e.g. proper escaping of the ubiquitous backslash). All TAB-completion suggestions as well as the corresponding help-text popups are customizable. They are defined in .xml-files distributed with the plug-in. These files can be changed to add additional hints, remove rarely used hints or change the descriptions.
Click on this link to get more detail: http://www.bastian-bergerhoff.com/eclipse/features/web/QuickREx/toc.html
Recommend the tutorial