if (isClosed()) throw new SocketException("socket is closed");
  public void bind (SocketAddress address)    throws SocketException  {    if (! (address instanceof InetSocketAddress))      throw new IllegalArgumentException ();    InetSocketAddress tmp = (InetSocketAddress) address;    SecurityManager s = System.getSecurityManager ();    if (s != null)      s.checkListen(tmp.getPort ());    impl.bind (tmp.getPort (), tmp.getAddress ());  }