NETWORKING - Introduction to Java Programming: Comprehensive Version - page 1157

Player 1 Server Player 2

1. Initialize user interface. Create a server socket. 1. Initialize user interface.

2. Request connection to the server
and learn which token to use from the
server.

Accept connection from the first player and notify
the player who is Player 1 with token X.

Accept connection from the second player and
notify the player who is Player 2 with token O.
Start a thread for the session.
Handle a session:

2. Request connection to the server and
learn which token to use from the server.

1. Tell Player 1 to start.

3. Get the start signal from the server.

2. Receive row and column of the selected cell from
Player 1.

4. Wait for the player to mark a cell,
send the cell's row and column index to
the server. 3. Receive status from the server.

3. Determine the game status (WIN, DRAW,
CONTINUE). If Player 1 wins, or draws, send the status
(PLAYER1_WON, DRAW) to both players and send
Player 1's move to Player 2. Exit.

5. Receive status from the server. 4. If WIN, display the winner. If Player 1

wins, receive Player 1's last move, and
break the loop.

6. If WIN, display the winner; if Player
2 wins, receive the last move from
Player 2. Break the loop.

4. If CONTINUE, notify Player 2 to take the turn, and
send Player 1's newly selected row and column index to
Player 2.

5. If DRAW, display game is over , and
receive Player 1's last move, and break
the loop. 7. If DRAW, display game is over;

break the loop.

5. Receive row and column of the selected cell from
Player 2.

6. If CONTINUE, receive Player 1's
selected row and index and mark the cell
for Player 1.

6. If Player 2 wins, send the status (PLAYER2_WON)
to both players, and send Player 2's move to Player 1.
Exit.

8. If CONTINUE, receive Player 2's
selected row and column index and
mark the cell for Player 2.

7. Wait for the player to move, and send
the selected row and column to the
server.

7. If CONTINUE, send the status, and send Player 2's
newly selected row and column index to Player 1.

F IGURE 31.13

The server starts a thread to facilitate communications between the two players.

■ TicTacToeClient models a player in Listing 31.10.

■ Cell models a cell in the game. It is an inner class in TicTacToeClient .

■ TicTacToeConstants is an interface that defines the constants shared by all the
classes in the example in Listing 31.8.

The relationships of these classes are shown in Figure 31.14.

L ISTING 31.8

TicTacToeConstants.java
1 public interface TicTacToeConstants {
2 public static int PLAYER1 = 1 ; // Indicate player 1

3 public static int PLAYER2 = 2 ; // Indicate player 2

4 public static int PLAYER1_WON = 1 ; // Indicate player 1 won

5 public static int PLAYER2_WON = 2 ; // Indicate player 2 won

6 public static int DRAW = 3 ; // Indicate a draw

7 public static int CONTINUE = 4 ; // Indicate to continue

8 }

L ISTING 31.9

TicTacToeServer.java
1 import java.io.*;
2 import java.net.*;
3 import java.util.Date;
4 import javafx.application.Application;