How to find hostname from IP Address in Java

Problem Description

How to find hostname from IP Address?

Solution

Following example shows how to change the host name to its specific IP address with the help of InetAddress.getByName() method of net.InetAddress class.

import java.net.InetAddress;

public class Main {
   public static void main(String[] argv) throws Exception {
      InetAddress addr = InetAddress.getByName("74.125.67.100");
      System.out.println("Host name is: "+addr.getHostName());
      System.out.println("Ip address is: "+ addr.getHostAddress());
   }
}

Result

The above code sample will produce the following result.

Host name is: 100.67.125.74.bc.googleusercontent.com
Ip address is: 74.125.67.100

The following is an example to find hostname from IP Address

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

public class NewClass1 {
   public static void main(String[] args) {
      InetAddress ip;
      String hostname;
      try {
         ip = InetAddress.getLocalHost();
         hostname = ip.getHostName();
         System.out.println("Your current IP address : " + ip);
         System.out.println("Your current Hostname : " + hostname);
      } catch (UnknownHostException e) {
         e.printStackTrace();
      }
   }
}

The above code sample will produce the following result.

Your current IP address : localhost/127.0.0.1
Your current Hostname : localhost