Java program to find the whether given IP is IPv4 or IPv6

import java.util.regex.Pattern;

/**
 * Program to find whether given ip is IPv4 or IPv6 address
 * 
 * @author sahir maredia (Kotia Solutions)
 * 
 */
public class IPType {

 private static final String IPv4 = "(([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.){3}([01]?\\d\\d?|2[0-4]\\d|25[0-5])";
 private static final String IPv6 = "([0-9a-f]{1,4}:){7}([0-9a-f]){1,4}";

 /**
  * @param args
  */
 public static void main(String[] args) {
  if (args.length != 1) {
   System.out.println("Please provide IP address as argument");
   return;
  }
  String ipaddress = args[0];
  
  Pattern ipv4 = Pattern.compile(IPv4);
  Pattern ipv6 = Pattern.compile(IPv6);
  if (ipv4.matcher(ipaddress).matches()) {
   System.out.println("Given IP Address : " + ipaddress + " is IPv4");
   return;
  } else if (ipv6.matcher(ipaddress).matches()) {
   System.out.println("Given IP Address : " + ipaddress + " is IPv6");
   return;
  } else {
   System.out.println("Given string is an invalid IP address");
  }
 }

}

Run this program as follows :

sahir@sahir-laptop:~/networklab$ javac IPType.java
sahir@sahir-laptop:~/networklab$ java IPType 192.168.1.1
Given IP Address : 192.168.1.1 is IPv4
sahir@sahir-laptop:~/networklab$ java IPType 0000:ffff:1234:4567:0000:4321:4567:ffff
Given IP Address : 0000:ffff:1234:4567:0000:4321:4567:ffff is IPv6
sahir@sahir-laptop:~/networklab$