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Regular expression match group example

This is an example of how to use a regular expression match group. Using a regular expression to group matches of a String with a pattern 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 find() API method of Matcher to get the matches of the input with the pattern.
  • Use group(int group) API method to get the input subsequence captured by the given group during the previous match operation.

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;

/**
 * REmatch -- demonstrate RE Match -> group()
 *
 */
public class MatchGroup {

    public static void main(String[] argv) {


  String pattern = "Q[^u]\d+\.";

  Pattern reg = Pattern.compile(pattern);

  String str = "Order QT300. Now!";

  Matcher matcher = reg.matcher(str);

  if (matcher.find()) {


System.out.println(pattern + " matches "" + matcher.group(0) + "" in ""



  + str + """);

  } else {


System.out.println("NO MATCH");

  }
    }
}

Output:

Q[^u]d+. matches "QT300." in "Order QT300. Now!"

  
This was an example of how to use a regular expression match group in Java.

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