# Java Regular Expression Help

**URL:** <https://boards.straightdope.com/t/java-regular-expression-help/325202>\
**Category:** Factual Questions\
**Created:** [October 7, 2005, 3:17pm UTC](https://boards.straightdope.com/t/java-regular-expression-help/325202 "2005-10-07T15:17:55Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![rayray5884](https://avatars.discourse-cdn.com/v4/letter/r/57b2e6/32.png) [@rayray5884](https://boards.straightdope.com/u/rayray5884)\
**Post date:** [October 7, 2005, 3:17pm UTC](https://boards.straightdope.com/t/java-regular-expression-help/325202/1 "2005-10-07T15:17:55Z")

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Although I’m rather new to the Java Regex scene I think I have a pretty good grasp on the concepts. That being said I have a problem. What I’m trying to do is search through an htm file and find a string that looks like either of the following:

VALUE=“this is the string i want”  
NAME=“or this is what i want”

Basically the goal is to extract the string within the quotes if a VALUE attribute exists OR a NAME attribute if the VALUE does not exist. So I can easily do the following:

Pattern style = Pattern.compile(“VALUE=”([^"]\*)"");

Check to see if I found a match, and if not recompile with the NAME attribute instead and process all over again. I’m relatively sure I can combine these into something that looks like this:

Pattern style = Pattern.compile(“VALUE=”([^"]_)" | NAME="([^"]_)"");

This way I can check either OR and group the string of whichever one it finds. The problem is it doesn’t seem to work and won’t find a match.

My question is, is this correct syntax or am I just not able to match and group something like this? If you need any other information just let me know. Thanks in advance!

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**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\
**Post date:** [October 7, 2005, 3:24pm UTC](https://boards.straightdope.com/t/java-regular-expression-help/325202/2 "2005-10-07T15:24:21Z")

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That’s not exactly right, because the " character has meaning in a regular expression, so you need to escape it(Java Regular Expressions are quite annoying for things like this). You want:

String regexp = “(VALUE|NAME)=\\”([^"]\*)\\"";  
Pattern.compile(regexp);  
// and so on

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**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\
**Post date:** [October 7, 2005, 3:25pm UTC](https://boards.straightdope.com/t/java-regular-expression-help/325202/3 "2005-10-07T15:25:33Z")

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Wait, I messed that up. It should be:

String regexp = “(VALUE|NAME)=\”([^"]\*)\"";

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**Author:** ![rayray5884](https://avatars.discourse-cdn.com/v4/letter/r/57b2e6/32.png) [@rayray5884](https://boards.straightdope.com/u/rayray5884)\
**Post date:** [October 7, 2005, 3:36pm UTC](https://boards.straightdope.com/t/java-regular-expression-help/325202/4 "2005-10-07T15:36:32Z")

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Thanks **Rysto**!

I was looking at that earlier and figured I was trying to OR too much. This ended up working for me:

Pattern.compile(“VALUE|NAME=”([^"]\*)"");

Kind of…

This is what I’m looking at in my html file:

\<PARAM NAME=“string-name” VALUE=“string-value”\>

If a VALUE exists I’d prefer that over the NAME but apparently the regex doesnt check the expressions in order. Is there another way for me to do this or am I stuck compiling and checking for each one in order to check in the right order?

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**Author:** ![rayray5884](https://avatars.discourse-cdn.com/v4/letter/r/57b2e6/32.png) [@rayray5884](https://boards.straightdope.com/u/rayray5884)\
**Post date:** [October 7, 2005, 3:45pm UTC](https://boards.straightdope.com/t/java-regular-expression-help/325202/5 "2005-10-07T15:45:30Z")

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Now that I think about it that makes perfect sense. I have no idea why I thought it wouldn’t check it like it is. :smack:

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**Author:** ![jawdirk](https://avatars.discourse-cdn.com/v4/letter/j/df705f/32.png) [@jawdirk](https://boards.straightdope.com/u/jawdirk)\
**Post date:** [October 7, 2005, 6:53pm UTC](https://boards.straightdope.com/t/java-regular-expression-help/325202/6 "2005-10-07T18:53:31Z")

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You want to use the repeating search capability of Matcher.find()

Use Matcher.find(). Use the pattern (VALUE|NAME)="(^"\*)" if the search succeeds and Matcher.group(1) is VALUE then you’re done, just get Matcher.group(2). If Matcher.group(1) is NAME, save Matcher.group(2) in a variable and call Matcher.find() again. If you get a match, check that Matcher.group(1) is VALUE and if it is, use Matcher.group(2) instead of the variable you saved.

Make sense?