Killer Game Programming in Java

Comparing NetFourByFour and FourByFour

Many classes in NetFourByFour are similar to those in FourByFour; this is a consequence of keeping the game logic on the client side.

The Positions class, which manages the on-screen markers is unchanged from FourByFour. PickDragBehavior still handles user picking and dragging, but reports a selected position to NetFourByFour rather than to Board. The game data structures in Board are as before, but the tryMove() method for processing a move and the reportWinner() are different. WrapNetFourByFour is similar to WrapFourByFour but utilizes the OverlayCanvas class rather than Canvas3D.

The NetFourByFour class is changed since the networking code for the client side is located there. FBFWatcher is used to monitor messages coming from the server, so it is new.

Game Initialization in the Client

The network initialization done in NetFourByFour consists of opening a connection to the server and creating a FBFWatcher thread to wait for a response:

    // globals in NetFourByFour
    private Socket sock;
    private PrintWriter out;
   
   
    private void makeContact()   // in NetFourByFour
    {
      try {
        sock = new Socket(HOST, PORT);
        BufferedReader in  = new BufferedReader(
                                  new InputStreamReader( sock.getInputStream() ));
        out = new PrintWriter( sock.getOutputStream(), true );
   
        new FBFWatcher(this, in).start();  // start watching server
      }
      catch(Exception e)
      { System.out.println("Cannot contact the NetFourByFour Server");
        System.exit(0);
      }
    }  // end of makeContact()

A consideration of Figure ...