Fetches the public IP of the machine

IPUtil.java

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

public class IPUtil
{
    /**
     * Returns true if the ip is private IP
     * @param ip
     * @return
     */
    public static boolean isPrivateIP( String ip )
    {
        boolean local = ip.startsWith( "192.168." ) || ip.startsWith( "10." );
        if ( local ) {
            return true;
        } else {
            if ( ip.startsWith( "172." ) ) {
                Integer second = Integer.parseInt( ip.split( "\\." )[1] );
                if ( second >= 16 && second <= 31 ) {
                    return true;
                }
            }
        }
        return false;
    }


    public static boolean isLocalHost( String ip )
    {
        return "127.0.0.1".equals( ip );
    }


    /**
     * Returns the most 'public' IP
     * @return
     * @throws SocketException
     */
    public static String getIP() throws SocketException
    {
        Enumeration e = NetworkInterface.getNetworkInterfaces();
        List<String> allIPs = new ArrayList<>();
        while ( e.hasMoreElements() ) {
            NetworkInterface n = (NetworkInterface) e.nextElement();
            Enumeration ee = n.getInetAddresses();
            while ( ee.hasMoreElements() ) {
                InetAddress i = (InetAddress) ee.nextElement();
                allIPs.add( i.getHostAddress() );
            }
        }

        for ( String ip : allIPs ) {
            if ( isPrivateIP( ip ) || isLocalHost( ip ) ) {
                continue;
            }
            // Return the first non-private, non-localhost ip
            return ip;
        }

        // If no public IP is found, return the first private IP
        for ( String ip : allIPs ) {
            if ( isLocalHost( ip ) ) {
                continue;
            }
            // Return the first non-private, non-localhost ip
            return ip;
        }

        // If nothing else works, return localhost
        return "127.0.0.1";
    }
}