if (networkInterfaces == null) networkInterfaces = getRealNetworkInterfaces ();
Vector networkInterfaces = getRealNetworkInterfaces ();
  public static Enumeration getNetworkInterfaces ()    throws SocketException  {    if (networkInterfaces == null)      networkInterfaces = getRealNetworkInterfaces ();    Enumeration tmp = networkInterfaces.elements ();    if (tmp.hasMoreElements ())      return tmp;    return null;  }