code: public static long getMacAddr() {
          if (macAddr == 0) {
              try {
                  InetAddress ip = InetAddress.getLocalHost();
                  NetworkInterface network = NetworkInterface.getByInetAddress(ip);
                  byte[] mac = network.getHardwareAddress();
                  for (byte temp : mac) {
                      macAddr = (macAddr << 8) | ((int) temp & 0xFF);
                  }
              } catch (Exception e) {
                  macAddr = 0;
              }
          }
          return macAddr;
      }
docs: Returns host's MAC address.
  
  @return