Matcher group example – Part 2

Byron KiourtzoglouNovember 11th, 2012Last Updated: August 14th, 2013

0 47 1 minute read

This is an example of how to use Matcher.group(int group) API method to get the input subsequence captured by the given group during the previous match operation. Grouping with a Matcher implies that you should:

Compile a String regular expression to a Pattern, using compile(String regex) API method of Pattern.
Use matcher(CharSequence input) API method of Pattern to create a Matcher that will match the given String input against this pattern.
Use group(int group) API method to get subsequence captured by the group during the previous match, or null if the group failed to match part of the input.

Let’s take a look at the code snippet that follows:

package com.javacodegeeks.snippets.core;

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

public class MatcherGroup {
  public static void main(String args[]) {
    String regex = "(\w+)(\d\d)(\w+)";

    Pattern pattern = Pattern.compile(regex);

    String candidate = "X99SuperJava";

    Matcher matcher = pattern.matcher(candidate);

    matcher.find();

    System.out.println(matcher.group(1));
    System.out.println(matcher.group(2));
    System.out.println(matcher.group(3));
  }
}

Output: