Finding duplication of words : Validation « Regular Expressions « Java Tutorial

1. Java Tutorial
2. Regular Expressions
3. Validation

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

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

    String phrase = "a word word";
    String duplicatePattern = "\\b(\\w+) \\1\\b";

    Pattern p = null;
    try {
      p = Pattern.compile(duplicatePattern);
    } catch (PatternSyntaxException pex) {
      pex.printStackTrace();
      System.exit(0);
    }
    // count the number of matches.
    int matches = 0;

    // get the matcher
    Matcher m = p.matcher(phrase);
    String val = null;

    // find all matching Strings
    while (m.find()) {
      val = ":" + m.group() + ":";
      System.out.println(val);
      matches++;
    }
  }
}