Simple validation using the Pattern and Matcher objects : Introduction « Regular Expressions « Java Tutorial

1. Java Tutorial
2. Regular Expressions
3. Introduction

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

public class MainClass {
  public static void main(String args[]) {

    Pattern p = null;
    try {
      p = Pattern.compile("Java \\d");
    } catch (PatternSyntaxException pex) {
      pex.printStackTrace();
      System.exit(0);
    }

    String candidate = "Java 4";
    Matcher m = p.matcher(candidate);

    if (m != null)
      System.out.println(m.find());
  }
}