Java program to find IP address of your computer

An IP(Internet Protocol) address is an identifier assigned to each computer and other device(e.g., router, mobile, etc) connected to a TCP/IP network that is used to locate and identify the node in communication with other nodes on the network. IP addresses are usually written and displayed in human-readable notation such as 192.168.1.35 in IPv4(32-bit IP address).

An IP address serves two principle functions : host or network interface identification and local addressing. It’s role has been characterized as follows : “A name indicate what we seek. An address indicate where it is. A route indicate how to get there.”

Prerequisites : Networking in Java | Set 1 (InetAddress class), trim() in Java.

InetAddress.getLocalHost() is used to find private IP address used in LAN or any other local network.

To find public IP, we use http://bot.whatismyipaddress.com (An online utility to find your public IP), we open the URL, read a line and print the line.

Below is Java implementation of above steps.

// Java program to find IP address of your computer
// java.net.InetAddress class provides method to get
// IP of any host name
import java.net.*;
import java.io.*;
import java.util.*;
import java.net.InetAddress;

public class JavaProgram
{
    public static void main(String args[]) throws Exception
    {
        // Returns the instance of InetAddress containing
        // local host name and address
        InetAddress localhost = InetAddress.getLocalHost();
        System.out.println("System IP Address : " +
                      (localhost.getHostAddress()).trim());

        // Find public IP address
        String systemipaddress = "";
        try
        {
            URL url_name = new URL("http://bot.whatismyipaddress.com");

            BufferedReader sc =
            new BufferedReader(new InputStreamReader(url_name.openStream()));

            // reads system IPAddress
            systemipaddress = sc.readLine().trim();
        }
        catch (Exception e)
        {
            systemipaddress = "Cannot Execute Properly";
        }
        System.out.println("Public IP Address: " + systemipaddress +"\n");
    }
}

Output:

 System IP Address : 10.0.8.204
 Public IP Address : 35.166.48.97

Note : The above output is for machine that is used by GeeksforGeeks online compiler, ide.geeksforgeeks.org

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