Program: How to validate user name using regular expression?

The below given example shows how to validate a user name. The regular expression pattern allows lower case alphanumeric characters, allows '-', '_'. Incase if you want to support uppercase characters then regular expression should be ^[a-zA-Z0-9_-]{6,14}$

package com.java2novice.regex;

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

public class MyUsernameValidate {

	private static Pattern usrNamePtrn = Pattern.compile("^[a-z0-9_-]{6,14}$");
	
	public static boolean validateUserName(String userName){
		
		Matcher mtch = usrNamePtrn.matcher(userName);
		if(mtch.matches()){
			return true;
		}
		return false;
	}
	
	public static void main(String a[]){
		System.out.println("Is 'java2novice' a valid user name? "
						+validateUserName("java2novice"));
		System.out.println("Is 'cric' a valid user name? "
						+validateUserName("cric"));
		System.out.println("Is 'JAVA2NOVICE' a valid user name? "
						+validateUserName("JAVA2NOVICE"));
		System.out.println("Is 'java.2.novice' a valid user name? "
						+validateUserName("java.2.novice"));
		System.out.println("Is 'java_2-novice' a valid user name? "
						+validateUserName("java_2-novice"));
	}
}

Is 'java2novice' a valid user name? true
Is 'cric' a valid user name? false
Is 'JAVA2NOVICE' a valid user name? false
Is 'java.2.novice' a valid user name? false
Is 'java_2-novice' a valid user name? true