Comments on: java.lang.IllegalArgumentException: Illegal group reference in String.replaceAll

By: Raghavan alias Saravanan M

Raghavan alias Saravanan M — Sat, 15 Oct 2011 09:32:09 +0000

A good post!

// This incident reminds me that debugging can teach us a lot than the actual development.//

Well said

By: Ali Hammad

Ali Hammad — Fri, 14 Oct 2011 11:41:10 +0000

Thank you very much Veera, that solved my problem. A huge string that may take a whole day to find the error. I just removed $ and its working, wow, what a fail:P

By: Veera

Veera — Thu, 28 Apr 2011 06:29:37 +0000

that should word.

By: Philon

Philon — Wed, 27 Apr 2011 12:24:39 +0000

dudes,

String oldPattern = Pattern.quote( aOldPattern );
String newPattern = Matcher.quoteReplacement( aNewPattern );
return aInput.replaceAll( oldPattern, newPattern );

By: thizz

thizz — Fri, 29 Oct 2010 10:56:32 +0000

thx you saved a lot of my time

By: Veera

Veera — Mon, 25 Jan 2010 07:10:45 +0000

according to the API documentation of Matcher.appendReplacement method,

The replacement string may contain references to subsequences captured during the previous match: Each occurrence of $g will be replaced by the result of evaluating group(g).

and that's what I meant by grouping.

By: Sreenivas

Sreenivas — Mon, 25 Jan 2010 05:02:35 +0000

Veera, the replaceAll method takes in regular expressions as the parameter and ‘$’ in regex is a special character that represents end of a line.

Grouping, on the other hand is done using parantheses.

By: Veera

Veera — Thu, 21 Jan 2010 03:07:38 +0000

I haven’t tested the code for other regex symbols, but I guess those symbols also should be escaped.

By: JB

JB — Thu, 21 Jan 2010 00:18:24 +0000

Yes, debugging teaches a few lessons.

I thought it was due to $ being a regex symbol. Pardon me, I am not a Java programmer, but know javascripting.

java.util.regex namespace gave me solace

Did you try with other regex symbols like ^

By: Veera

Veera — Wed, 20 Jan 2010 15:50:13 +0000

agreed. Otherwise it is little difficult to figure it out why the replaceAll() method fails.