Chapter 11

Developing a Tic-Tac-Toe Applet

Now that you’re familiar with the basics of Java applets, it’ll be nice to write a program a bit more useful than Hello World. In this lesson you’ll program the game of tic-tac-toe as a Java Swing applet.

Every game implements some algorithm — a set of rules or a strategy that has to be applied depending on the player’s actions. The algorithms for the same game can be simple or very complicated. When you hear that the world chess champion plays against a computer, he actually plays against a program. Teams of experts are trying to invent sophisticated algorithms to beat him. Let’s come up with the algorithm for tic-tac-toe.

The Strategy

In the unlikely event that you aren’t familiar with tic-tac-toe, or if it has a different name in your part of the world, read the following Wikipedia article: http://en.wikipedia.org/wiki/Tic-tac-toe. Our version of the popular game will implement the following strategy:

  • The game will be played on a two-dimensional board of three cells by three cells.
  • Two players can play this game. One will play with the symbol X, and the other will use O.
  • The winner must have a full row, column, or diagonal of his or her designated symbol.
  • After each move, the program has to check if there is a winner.
  • The game should end if there are no empty squares left.
  • The player has to press the New Game button to play again.
  • When the program makes a decision about where to put the next letter O, it has to try to find a row, ...

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