JRegexpTester is a standalone Swing application that helps you test regular expressions with the Sun Java standard API (java.util.regex). The extracted data can be modified with formatters similar to those used by sprintf, or with standard Java date and decimal formatters. It features RegExLib library integration with more than 900 patterns.

Since the release 0.3, JRegexpTester helps you manage CSV (comma-separated values) files.


Default demoPreferencesLarge file
Large regexpSplitRegexp Search
large regexpsplitsearch
Choice of fonts


JRegexpTester provides the following features :

  • easy to use interface.
  • immediate response.
  • large file extraction permitted (line by line).
  • automatic integration of the entire RegExLib.com library (more than 1000 patterns ready to use except those .Net specific).
  • save/load/export(text,html)/search
  • users can easily see all the groups capturing text moving the cursor into the pane of details.
  • the open-close brackets (curly and square) and parenthesis are clearly highlighted into the regexp text area.
  • easy CSV file management (extract/transform). JRegexpTester can help you manage files with more than 65536 rows which can't be read entirely by Gnumeric.

Very interesting : the CsvParser used by JRegexpTester is explained in details by its author Julian M Bucknall at http://www.boyet.com/.


Top Ten Data Crunching Tips and Tricks (06/09/2005)

"... As well as illustrating reluctant matches, this example also shows why regular expressions can be so hard to debug: adding one character completely changes the way the RE behaves. This is why I'm very fond of graphical tools for building and debugging REs, such as Edi Weitz's Regex Coach, JRegexpTester, and the Rx Toolkit in ActiveState's Komodo IDE."

Greg Wilson has been crunching data for more than 20 years. He is an independent programming consultant, an adjunct professor at the University of Toronto, and a contributing editor with Doctor Dobb's Journal. He is the author of Data Crunching and Practical Parallel Programming.

My favorite motto is :


The quality that makes you go to great effort to reduce overall energy expenditure. It makes you write labour-saving programs that other people will find useful, and document what you wrote so you don't have to answer so many questions about it. Hence the first great virtue of a programmer."

Larry Wall [Programming Perl, Larry Wall and Randal. L. Schwartz, 1992 O'Reilly and Associates, Inc., page 426.]

If you appreciate JRegexpTester or have any suggestions, you are free to send me your comments.


Rated top 5% by the JARS panel of judges. Score : 960 (out of a possible 1000.) 
		Presentation : 200 points ( out of possible 200 )
		AppletPerfect: 300 points ( out of possible 300 )
( www.jars.com )

Listed into the "Java News Headlines" of java.net 
powered by Sun Microsystems, Inc., O'Reilly and CollabNet (30 May 2005)

( http://today.java.net/today/archive/index_05302005.html )
Great Software!   
2004-09-22 09:00  

This is very useful! And looks quite programmer-friendly too! 
(I mean, user-friendly, but the user is a programmer :) 

Gustavo Hexsel ( The Edmonton Java Meetup Group - Canada ) 
Excellent for testing
Mon, 24 Jan 2005 02:23:01 -0800

To learn more about regexp I strongly recommend you download JRegexpTester.
It's excellent for testing.

Anders Haal ( www.ingby.com ) 

Help and contact

JRegexpTester has a help file (F1). This set of samples are designed to act as tutorial too.

You can also send a mail to the project administrator, who is Alain Cabon. Any feedback, including error statements, is more than welcome.