title: how to get machines mac address
body: <p>I want get machines' MAC address..but below written code only display the MAC address when Internet is connected to my machine other it will return null... I am using windows 7</p>
  
  <pre><code>import java.net.InetAddress;
  import java.net.NetworkInterface;
  import java.net.SocketException;
  import java.net.UnknownHostException;
  
  class test
  {
      public static void main(String[] args)
      {
          InetAddress ip;
          try {
              ip = InetAddress.getLocalHost();
  
              System.out.println("The mac Address of this machine is :" + ip.getHostAddress());
  
              NetworkInterface network = NetworkInterface.getByInetAddress(ip);
  
              byte[] mac = network.getHardwareAddress();
  
              System.out.print("The mac address is : ");
  
              StringBuilder sb = new StringBuilder();
              for (int i = 0; i &lt; mac.length; i++){
                  sb.append(String.format("%02X%s", mac[i],(i&lt; mac.length - 1)?"-":""));
              }
  
              System.out.println(sb.toString());
  
          } 
          catch (UnknownHostException e) {
              e.printStackTrace();
          } 
          catch (SocketException e) {
              e.printStackTrace();
          }
      }
  }
  </code></pre>