pick 3rd number in String

Question

Given this String: "a001212a a1212a a00333a a00334a abvbv";

I'm trying to pick the third number just by changing the regex. But I can't figure it out. I am only allowed to change the regex. My code below works if i change the argument to matcher.group(2) but not for group(1).

Help?

String nthNumber(String string) {
        Pattern pat = Pattern.compile(
                "(\\D+0*(\\d+)\\D+){3,}.*"
        );

        Matcher matcher = pat.matcher(string);
        matcher.matches();
        return matcher.group(1);
    }

Answer 1

You can make the first group a non-capturing group like below. Then, group(1) should work.

String nthNumber(String string) {
        Pattern pat = Pattern.compile(
                "(?:\\D+0*(\\d+)\\D+){3,}.*"
        );

        Matcher matcher = pat.matcher(string);
        matcher.matches();
        return matcher.group(1);
    }