NPE while assign the Null value to primitive at runtime

public class TestOutput {

     public static void main(String[] args) {

           int value = solution();

           System.out.println(value);

     }

     private static int solution() {

           return true?0:null;

     }

}

Output: 0

When we assign the null value to primitive at runtime, it will throw NullPointerException.

public classTestOutput {

     public static voidmain(String[] args) {

           int value = solution();

           System.out.println(value);

     }

     private static intsolution() {

           return true?null:0;

     }

}

Output:

Exception in thread "main" java.lang.NullPointerException at TestOutput.solution(TestOutput.java:10) at TestOutput.main(TestOutput.java:5)

How do I get MAC address of a host?

In JDK 1.6 a new method is added in the java.net.NetworkInterface class, this method is getHardwareAddress().

import java.net.InetAddress;

import java.net.NetworkInterface;

import java.net.SocketException;

import java.net.UnknownHostException;

public class PrintMacAdress {

   public static void main(String[] args){

      try {

          InetAddress address = InetAddress.getLocalHost();

          //InetAddress address = InetAddress.getByName("www.google.co.in");

                 

          System.out.println("Current IP address : "+address.getHostAddress());

          NetworkInterface network = NetworkInterface.getByInetAddress(address);

          byte[] mac = network.getHardwareAddress();

          System.out.print("Current MAC address : ");

          StringBuilder sb = new StringBuilder();

          for (int i = 0; i < mac.length; i++) {

              sb.append(String.format("%02X%s",mac[i],(i<mac.length-1)?"-":""));

          }

          System.out.println(sb.toString());

    } catch(UnknownHostException e) {

    } catch(SocketException e){

    }

  }

}

Output:

      Current IP address : 192.168.230.215

      Current MAC address : D8-CB-8A-67-8B-3F