How can I check whether a port is in use?

public static boolean port_available(int port)
  {
    ServerSocket ss = null;
    DatagramSocket ds = null;
    try
    {
      ss = new ServerSocket(port);
      ss.setReuseAddress(true);
      ds = new DatagramSocket(port);
      ds.setReuseAddress(true);
      return true;
    }
    catch (IOException e)
    {     }
    finally
    {
      if (ds != null)
      {
        ds.close();
      }
      if (ss != null)
      {
        try
        {
          ss.close();
        }
        catch (IOException e)
        {
          /* should not be thrown */
        }
      }
    }
    return false;
  }