if (networkInterfaces == null) networkInterfaces = getRealNetworkInterfaces ();
Vector networkInterfaces = getRealNetworkInterfaces ();
  public static NetworkInterface getByInetAddress (InetAddress addr)    throws SocketException  {    if (networkInterfaces == null)      networkInterfaces = getRealNetworkInterfaces ();        for (Enumeration interfaces = networkInterfaces.elements ();         interfaces.hasMoreElements (); )      {        NetworkInterface tmp = (NetworkInterface) interfaces.nextElement ();              for (Enumeration addresses = tmp.inetAddresses.elements ();             addresses.hasMoreElements (); )          {            if (addr.equals ((InetAddress) addresses.nextElement ()))              return tmp;          }      }    throw new SocketException (      "no network interface is bound to such an IP address");  }