Question

Matcher.find finds the next subsequence, starting at a given index, which is compliant with the regex.

How can I make it so that it fails if the next character sequence is not compliant?

Ex:

    String input = "123456text123";
    Matcher mat1 = Pattern.compile("\\d+").matcher(input);

    mat1.find();
    System.out.println(mat1.group()); //123456
    mat1.find(mat1.end());
    System.out.println(mat1.group()); //123

I want to know if there’s a way to make the second find fail, since the next sequence does not match the mat1 pattern.

I want to be able to ‘compose’ matchers, in such a way that they MUST always be found in sequence.

Is it possible at all?

Answer 1

You can check that the previous mat1.end() equals the next mat1.start().

int lastEnd = -1;
while (mat1.find()) {

    // Was there any junk between last two matches?
    if (mat1.start() != lastEnd+1) {
        System.out.println("Fail.");
        break;
    }

    System.out.println(mat1.group());
    lastEnd = mat1.end();

}