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++;
}
}
}