How to get the ip of the computer on linux through Java?

Do not forget about loopback addresses, which are not visible outside. Here is a function which extracts the first non-loopback IP(IPv4 or IPv6)

private static InetAddress getFirstNonLoopbackAddress(boolean preferIpv4, boolean preferIPv6) throws SocketException {    Enumeration en = NetworkInterface.getNetworkInterfaces();    while (en.hasMoreElements()) {        NetworkInterface i = (NetworkInterface) en.nextElement();        for (Enumeration en2 = i.getInetAddresses(); en2.hasMoreElements();) {            InetAddress addr = (InetAddress) en2.nextElement();            if (!addr.isLoopbackAddress()) {                if (addr instanceof Inet4Address) {                    if (preferIPv6) {                        continue;                    }                    return addr;                }                if (addr instanceof Inet6Address) {                    if (preferIpv4) {                        continue;                    }                    return addr;                }            }        }    }    return null;}

From Java Tutorial

Why is InetAddress not a good solution? I don't see anything in the docs about cross platform compatibility?

This code will enumerate all network interfaces and retrieve their information.

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<NetworkInterface> 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<InetAddress> 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: bge0Name: bge0InetAddress: /fe80:0:0:0:203:baff:fef2:e99d%2InetAddress: /121.153.225.59Display name: lo0Name: lo0InetAddress: /0:0:0:0:0:0:0:1%1InetAddress: /127.0.0.1

This code worked 4me:

import java.net.InetAddress;import java.net.NetworkInterface;import java.net.SocketException;import java.util.Enumeration;public class ShowIp {    public static void main(String[] args) throws SocketException {        NetworkInterface ni = NetworkInterface.getByName("eth0");        Enumeration<InetAddress> inetAddresses =  ni.getInetAddresses();        while(inetAddresses.hasMoreElements()) {            InetAddress ia = inetAddresses.nextElement();            if(!ia.isLinkLocalAddress()) {                System.out.println("IP: " + ia.getHostAddress());            }        }    }}