/**
 * Check is the given string is an IP adresse.
 */
public static boolean isIp(String ip) {
	return ip != null && !ip.equals("") && ip.matches("^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$");
}