Matcher.appendReplacement method : Matcher « Regular Expressions « Java Tutorial

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

public class MainClass {
  public static void main(String args[]) {
    Pattern p = Pattern.compile("(\\w+) (\\w+)");
    StringBuffer sb = new StringBuffer();

    String candidateString = "Jack Lee";

    String replacement = "$2, $1";
    Matcher matcher = p.matcher(candidateString);

    matcher.appendReplacement(sb, replacement);

Lee, Jack

8.4.1.Create a Matcher from Pattern
8.4.2.Matcher.start() method
8.4.3.Matcher.end(int) method
8.4.4.Matcher.LookingAt method
8.4.5.Matcher.matches method
8.4.6.Matcher.pattern method
8.4.7.Matcher.replaceAll method
8.4.8.Matcher.reset(CharSequence) method method
8.4.10.Matcher.find method
8.4.11.Matcher.find(int) method
8.4.12.Find the starting point of the first 'Bond'
8.4.13.Demonstrates the usage of the Matcher.reset() method
8.4.14.Matcher.appendReplacement method
8.4.15.REGEX = '\\bdog\\b'
8.4.16.lookingAt vs matches