determining the class of an IPv4 address

package com.isga.isi.reseaux;

    import java.net.InetAddress;
    import java.net.UnknownHostException;

public class IPClasses {

    public static String findClass(InetAddress ia) {
        byte[] ip=ia.getAddress();
        String res=null;

        if ((ip[0]& 0x80)==0) res="A";
        if ((ip[0]& 0xC0)==0x80) res="B";
        if ((ip[0]& 0xE0)==0xC0) res="C";
        if ((ip[0]& 0xF0)==0xE0) res="D";
        if ((ip[0]& 0xF0)==0xF0) res="E";

        return res;
    }

    public static String printSquareBrackets(InetAddress ia) {

        byte[] ip=ia.getAddress();
        if(ip.length==4) { //adresse IPv4

        }else { //adresse IPv6

        }


        return null;
    }


public static void main(String[] args) {

            try {
                InetAddress myLocalHost = InetAddress.getLocalHost();
                System.out.println("My own \"local\" address is : " + myLocalHost);
                String name=null;
                int i;
                for (i = 0; i < args.length; i++) {
                    name=args[i];
                    InetAddress ia = InetAddress.getByName(name);
                    System.out.println("l'adresse "+ia + " est de classe "+findClass(ia));
                }
            } catch (UnknownHostException uhe) {
                System.out.println("Une exception a eu lieu:");
                System.out.println(uhe.getMessage());
            }
        }
    }