Prentice.Hall.Introduction.to.Java.Programming,.Brief.Version.9th.(2014).[sharethefiles.com]

688 Chapter 18 Applets and Multimedia
The tic-tac-toe board consists of nine cells, created using new Cell[3][3]. To determine
which player’s turn it is, you can introduce a variable named whoseTurn of the char type.
whoseTurn is initially 'X', then changes to 'O', and subsequently changes between 'X' and
'O' whenever a new cell is occupied. When the game is over, set whoseTurn to ' '.
How do you know whether the game is over, whether there is a winner, and who the winner,
if any, is? You can define a method named isWon(char token) to check whether a
specified token has won and a method named isFull() to check whether all the cells are
occupied.
Clearly, two classes emerge from the foregoing analysis. One is the Cell class, which handles
operations for a single cell; the other is the TicTacToe class, which plays the whole
game and deals with all the cells. The relationship between these two classes is shown in
Figure 18.12.
Cell
javax.swing.JApplet
9
1
TicTacToe
-whoseTurn: char
-cell: Cell[][]
-jlblStatus: JLabel
+TicTacToe()
+isFull(): boolean
+isWon(token: char): boolean
Indicates which player has the turn, initially X.
A 3 3, two-dimensional array for cells.
A label to display game status.
Constructs the TicTacToe user interface.
Returns true if all cells are filled.
Returns true if a player with the specified token has won.
FIGURE 18.12
The TicTacToe class contains nine cells.
Since the Cell class is only to support the TicTacToe class, it can be defined as an inner
class in TicTacToe. The complete program is given in Listing 18.10.
main class TicTacToe
LISTING 18.10
TicTacToe.java
1 import java.awt.*;
2 import java.awt.event.*;
3 import javax.swing.*;
4 import javax.swing.border.LineBorder;
5
6 public class TicTacToe extends JApplet {
7 // Indicate which player has a turn; initially it is the X player
8 private char whoseTurn = 'X';
9
10 // Create and initialize cells
11 private Cell[][] cells = new Cell[3][3];
12
13 // Create and initialize a status label
14 private JLabel jlblStatus = new JLabel("X's turn to play");
15
16 /** Initialize UI */
17 public TicTacToe() {
18 // Panel p to hold cells