Is there any regular expression to return the number of matches

May 19, 2022

I’m trying to return how many matches I’ve got using regex on a single text. I need the regex to be global and case insensitive so it can match what I need.

What I actually need is the following:

Given this regex String regex = "one[^\w]*million" (global and case-insensitive)
Given this text as input String text = "estoOne␣⏎␣Million jvegax ONE␣MILLION million one OnE>>% mIllion spam"
It should return 3 matches on the string count = 3

What I actually have is just a simple check that returns true or false if at least one of the character matches the sequence, but not the actual number of matches.

My code:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {

    public static void main(final String[] args) {
        Main.findStrongSpamWords();
    }

    public static void findStrongSpamWords() {
        final String body = "estoOne␣⏎␣Million jvegax ONE␣MILLION million one OnE>>% mIllion spam";
        final Pattern pattern = Pattern.compile("one[^\\w]*million", Pattern.CASE_INSENSITIVE);
        final Matcher matchResult = pattern.matcher(body);
        
        System.out.println(matchResult.find());
    }
}

>Solution :

There are no regex that can do that. However, with Java 9 and later, use Matcher.results().count().

    public static void findStrongSpamWords() {
        final String body = "estoOne␣⏎␣Million jvegax ONE␣MILLION million one OnE>>% mIllion spam";
        final Pattern pattern = Pattern.compile("one[^\\w]*million", Pattern.CASE_INSENSITIVE);
        final Matcher matchResult = pattern.matcher(body);
        
        System.out.println(matchResult.results().count());
    }

If you are on Java 8 or earlier, you must count yourself:

public static void findStrongSpamWords() {
    final String body = "estoOne␣⏎␣Million jvegax ONE␣MILLION million one OnE>>% mIllion spam";
    final Pattern pattern = Pattern.compile("one[^\\w]*million", Pattern.CASE_INSENSITIVE);
    final Matcher matchResult = pattern.matcher(body);
    
    int count = 0;
    while (matchResult.find()) {
      count++;
    }
    System.out.println(count);
}