How to get the LAN IP of a client using Java?

Question

How can i get the LAN IP-address of a computer using Java? I want the IP-address which is connected to the router and the rest of the network.

I\'ve tried something like

Answer 1

At first: There is no single address. Your machine has at least two adresses (127.0.0.1 on "lo" and maybe 192.168.1.1 on "eth1").

You want this: Listing network interfaces

As you may expect, you cannot automatically detect which one is connected to any of your routers, since this needs potentially complex parsing of your routing tables. But if you just want any non-local address this should be enought. To be sure, try to use this at least one time on vista or Windows 7, since they add IPv6 addresses.

import java.io.*;
import java.net.*;
import java.util.*;
import static java.lang.System.out;

public class ListNets 
{
    public static void main(String args[]) throws SocketException {
        Enumeration nets = NetworkInterface.getNetworkInterfaces();
        for (NetworkInterface netint : Collections.list(nets))
            displayInterfaceInformation(netint);
    }

    static void displayInterfaceInformation(NetworkInterface netint) throws SocketException {
        out.printf("Display name: %s\n", netint.getDisplayName());
        out.printf("Name: %s\n", netint.getName());
        Enumeration inetAddresses = netint.getInetAddresses();
        for (InetAddress inetAddress : Collections.list(inetAddresses)) {
            out.printf("InetAddress: %s\n", inetAddress);
        }
        out.printf("\n");
     }
}  

The following is sample output from the example program:

Display name: bge0
Name: bge0
InetAddress: /fe80:0:0:0:203:baff:fef2:e99d%2
InetAddress: /121.153.225.59

Display name: lo0
Name: lo0
InetAddress: /0:0:0:0:0:0:0:1%1
InetAddress: /127.0.0.1