Matcher.appendReplacement example

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

0 34 1 minute read

With this example we are going to demonstrate how to use Matcher.appendReplacement(StringBuffer sb, String replacement) API method to append to a StringBuffer the result of a Matcher. In short, to use a StringBuffer to append a Matcher’s result you should:

Compile a given 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.
Create a new StringBuffer.
Find the next subsequence of the input sequence that matches the pattern, with find() API method of Matcher and append it to the StringBuffer, implementing a non-terminal append-and-replace step, using appendReplacement(StringBuffer sb, String replacement) API method of Matcher.

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 AppendReplacement {
    
  public static void main(String args[]) {


    Pattern pattern = Pattern.compile("(another) (test)");
    StringBuffer sb = new StringBuffer();

    String candidateString = "This is another test.";

    String replacement = "$1 AAA $2";
    Matcher m = pattern.matcher(candidateString);
    m.find();

    m.appendReplacement(sb, replacement);
    String msg = sb.toString();
    System.out.println(msg);
    
  }
}

Output: