Extracting the same string structures with regex

Question

I'm running the next code:

Pattern p = Pattern.compile("(<http:.*>)");
    Matcher m = p.matcher("<http:[email protected]>,<http:[email protected]>");
    if (m.find()) {
        int groupCount = m.groupCount();
        for(int i = 0; i < groupCount; i++){
            String groupValue = m.group(i);
            System.out.println(groupValue);
        }
    } else {
        System.out.println("nothing was fined");
    }

And as output I have only one group value: "http:[email protected],http:[email protected]" But I expect that there should be two groups : Group_1: http:[email protected] Group_2: http:[email protected]

How should I change my regex to achieve this?

Thanks!

Or better yet, use a negated character class that matches anything but `>` instead of `.` : `]*>` — Aaron, Feb 27 '20 at 13:51

User9123 · Accepted Answer · 2020-02-27T14:02:05.730

1

It's not group. It will be group if your pattern look like "(http:.*)(http:.*)". Group is expression between parentheses. Try this:

Pattern p = Pattern.compile("(<http:([^>]+)>)");
Matcher m = p.matcher("<http:[email protected]>,<http:[email protected]>");
while (m.find()) {
    String groupValue = m.group(1); // m.group(2) for email only without http: and <>
    System.out.println(groupValue);
}

edited Feb 27 '20 at 14:02

answered Feb 27 '20 at 13:54

User9123

1,643
1
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Why group_2 match email? – denis Feb 27 '20 at 14:14
first group - expression within first parentheses - (]+)>) and second group - expression within second parentheses - ([^>]+) – User9123 Feb 27 '20 at 14:15

score 0 · Answer 2 · answered Feb 27 '20 at 13:56

Please refer below code:

   Pattern p = Pattern.compile("(<http:.*?>)");
    Matcher m = p.matcher("<http:[email protected]> , <http:[email protected]>");
    if (m.find()) {
        int groupCount = m.groupCount();
        for(int i = 0; i <= groupCount; i++){
            String groupValue = m.group(i);
            System.out.println("Group("+i+")"+groupValue);
        }
    } else {
        System.out.println("nothing was fined");
    }

Hope this will help you.

Alexandru Somai · Answer 3 · 2020-02-27T14:03:16.790

0

As @user3783243 suggested in one of the comments, you could change the regex to a non-greedy (lazy) evaluation, by adding a ? to the * quantifier:

*? Quantifier — Matches between zero and unlimited times, as few times as possible, expanding as needed (lazy)

The resulting regex would be:

(<http:.*?>)

Here's the test for it: https://regex101.com/r/7751x9/1

edited Feb 27 '20 at 14:03

answered Feb 27 '20 at 13:56

Alexandru Somai

1,395
1
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16

Extracting the same string structures with regex

3 Answers3