In java, when using regex to find patterns, how to get nested result?

Question

The case is that, I want to find string which satisfies "c+d" in a string "cccd". My code is as follows,

String str="cccd";
String regex="c+d";
Pattern pattern = Pattern.compile(regex);
Matcher matcher =pattern.matcher(str);
While(matcher.find()){
    System.out.println(matcher.group())
}

The result is only "cccd". But what I want is to get all the possible results, including nested ones, which are cd, ccd and cccd. How should I fix it, thanks in advance.

Have you tried matcher.group(2) ?

ponomandr
– ponomandr

2014-08-25 07:02:19 +00:00
Commented Aug 25, 2014 at 7:02 — ponomandr
– ponomandr, Commented Aug 25, 2014 at 7:02
Related: stackoverflow.com/questions/11228384/…

sp00m
– sp00m

2014-12-02 09:32:33 +00:00
Commented Dec 2, 2014 at 9:32 — sp00m
– sp00m, Commented Dec 2, 2014 at 9:32

Avinash Raj · Accepted Answer · 2014-08-25 07:06:28Z

5

Just Use a lookahead to capture the overlapping characters,

(?=(c+d))

And finally print the group index 1.

DEMO

Your code would be,

String str="cccd";
String regex="(?=(c+d))";
Pattern pattern = Pattern.compile(regex);
Matcher matcher =pattern.matcher(str);
while(matcher.find()){
    System.out.println(matcher.group(1));
}

Output:

cccd
ccd
cd

edited Aug 25, 2014 at 7:06

answered Aug 25, 2014 at 7:01

Avinash Raj

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