Descobrir o ip address

 public void getInterfaces() {
  try {
   Enumeration e = NetworkInterface.getNetworkInterfaces();

   while (e.hasMoreElements()) {
    NetworkInterface netface = (NetworkInterface) e.nextElement();
    System.out.println("Net interface: " + netface.getName());

    Enumeration e2 = netface.getInetAddresses();

    while (e2.hasMoreElements()) {
     InetAddress ip = (InetAddress) e2.nextElement();
     System.out.println("IP address: " + ip.toString());
    }
   }
  } catch (Exception e) {
   System.out.println("e: " + e);
  }
 }