Java: regex - groups in general

Question

Lets say i have some regex = "..(group1)..|..(group2).."

pattern.matcher(regex)
matcher.find()
// how can i access the result?? 
// i dont wanna use matcher.group(1) or matcher.group(2) 
// since i don't really know what will be the result.

As u can see i don't know how to get my result. im looking for something like matcher.getResultedGroup.. Could anyone please explain what should i do?

If u have other suggestion to expand my knowledge i'd love to hear..

Hi Popokoko, is there a reason why this question has no accepted answers? — Maarten Bodewes
– Maarten Bodewes, Commented Jun 30, 2012 at 10:06

Paul · Accepted Answer · 2012-05-28 22:33:57Z

2

You can use a single capturing group, with non capturing groups inside:

((?:group1)|(?:group2))

edited May 28, 2012 at 22:33

Paul

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answered May 28, 2012 at 22:24

Emmanuel Bourg

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2 Comments

Maarten Bodewes Over a year ago

There is no need to put parantheses around the complete regexp, the actual match of the full regexp is in group 0.

Emmanuel Bourg Over a year ago

Yes, this example is meaningful as part of a larger expression.

malenkiy_scot · Accepted Answer · 2012-05-28 22:32:43Z

1

Iterate over Matcher.start(groupNum). groupNum that is not 0, but starts at 0 is what you are looking for (assuming that it's your whole expression).

Otherwise include your whole subexpression into a capturing group: ((group1)|(group2)...) and compare the starting indexes of the inner groups to the outer group.

edited May 28, 2012 at 22:32

answered May 28, 2012 at 22:26

malenkiy_scot

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1 Comment

Popokoko Over a year ago

This is what ive been doing.. though it looks pretty wired it does work (but not perfect..) for (int m = 1; m <= matcher.groupCount(); m++) { if (matcher.group(m) != null) { r = matcher.group(m); } }

user3001 · Accepted Answer · 2012-05-28 22:31:39Z

0

See the Javadoc http://docs.oracle.com/javase/6/docs/api/java/util/regex/Pattern.html and http://docs.oracle.com/javase/6/docs/api/java/util/regex/Matcher.html

Maybe somthing like this will work:

while(matcher.find()) {
    String groupMatch = matcher.group(groupIndex)
}

matcher.find will try to find all subsequences (substrings) of a string which are matched by your regular expression.

edited May 28, 2012 at 22:31

answered May 28, 2012 at 22:24

user3001

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2 Comments

Popokoko Over a year ago

i should have mention im pretty new with regex and it takes a while to understand everything

user3001 Over a year ago

See my updated comment and the others as well, each of them are good on their own :)

Maarten Bodewes · Accepted Answer · 2012-05-29 00:19:41Z

0

You don't need to go into subgroups if you don't want to. The actual match is in group 0: Matcher.group(0) or the equivalent Matcher.group(). Note that you might want to use non-capturing groups to safe resources.

answered May 29, 2012 at 0:19

Maarten Bodewes

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