Question

public static void main(String args[]) {
    Pattern p = Pattern.compile("ab");  // Case 1
    Pattern p = Pattern.compile("bab");  // Case 2
    Matcher m = p.matcher("abababa");
    while(m.find()){
        System.out.print(m.start());
    }
}

When I used Case 1, then output is 024 as expected. But, when I used Case 2 then output is 1, but I was expected 13. So, anyone explain me, is there any exceptional rule in regex, which causes this output, if not. Then, why I’m getting this output.

Help appreciated !!

Note : Case 1 and Case 2 are independently used.

Answer 1

The match consumes the input, so the next match is found after the end of the previous match:

Position of “bab” matcher’s pointer before each match would be:

1. |abababa
2. abab|aba