Java:Tutorial - Tic-Tac-Toe

***John*** · #1 (**permalink**) 01-11-2007, 02:11 PM

Title: Tic-Tac-Toe: Contemplation to Compilation

Many games you play on the internet have been crafted from Java. This tutorial, inspired by another post in this forum, will show you step by step how to create a two person Tic-Tac-Toe game in Java.

Prerequisites
This is a fairly intermediate tutorial, therefore if you are going to understand everything I write, you should read all my previous tutorials, in particular, those dealing with graphical user interfaces.

Solution
The first step you must take before starting any programming project is to understand your problem. Understanding your problem will allow you to create a logically correct program bug free, so before we delve into the code let me tell you what I was thinking when I presented myself with this problem.

The first question I asked myself is: “What is tic-tac-toe?”
It’s a game consisting of a 3 by 3 grid. Each player (represented by X and O) takes alternating turns trying to earn three of their letters in a row horizontally, vertically, or diagonally.

At this point I knew I needed to make a grid layout 3 by 3. My idea was to create 9 buttons in each of the grid boxes. But buttons would respond when clicked with either a X or an O depending on who’s turn it was.

Code:

 package mytictactoe;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;


public class TicTacToeV1 implements ActionListener {
	/*Instance Variables*/
	private JFrame window = new JFrame("Tic-Tac-Toe");
	private JButton button1 = new JButton("x");
	private JButton button2 = new JButton("x");
	private JButton button3 = new JButton("x");
	private JButton button4 = new JButton("x");
	private JButton button5 = new JButton("x");
	private JButton button6 = new JButton("x");
	private JButton button7 = new JButton("x");
	private JButton button8 = new JButton("x");
	private JButton button9 = new JButton("x");


	
	public TicTacToeV1(){

	/*Create Window*/
	window.setSize(300,300);
	window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	window.setLayout(new GridLayout(3,3));
	
	/*Add Buttons To The Window*/
	window.add(button1);
	window.add(button2);
	window.add(button3);
	window.add(button4);
	window.add(button5);
	window.add(button6);
	window.add(button7);
	window.add(button8);
	window.add(button9);
	
	/*Add The Action Listener To The Buttons*/
	button1.addActionListener(this);
	button2.addActionListener(this);
	button3.addActionListener(this);
	button4.addActionListener(this);
	button5.addActionListener(this);
	button6.addActionListener(this);
	button7.addActionListener(this);
	button8.addActionListener(this);
	button9.addActionListener(this);
	
	/*Make The Window Visible*/
	window.setVisible(true);
	}
	
	public void actionPerformed(ActionEvent a) {
	System.out.println("A button was pressed.");
		
	}
	
	public static void main(String[] args){
		new TicTacToeV1();
	}
}

What you see is a window with nine buttons labeled X. Each time the button is pressed it invokes the actionPerformed method and prints to the consol “A buttons was pressed.” My next step was to, when the program was started, have the buttons blank, and when pressed, label them X. To do that I set the label to null when the object was first created in the instance variables. Then in the actionPerformed method, I had the button label change to X if it was pressed by doing this

Code:

 package mytictactoe;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;


public class TicTacToeV1 implements ActionListener {
	/*Instance Variables*/
	private JFrame window = new JFrame("Tic-Tac-Toe");
	private JButton button1 = new JButton("");
	private JButton button2 = new JButton("");
	private JButton button3 = new JButton("");
	private JButton button4 = new JButton("");
	private JButton button5 = new JButton("");
	private JButton button6 = new JButton("");
	private JButton button7 = new JButton("");
	private JButton button8 = new JButton("");
	private JButton button9 = new JButton("");
	
	public TicTacToeV1(){
	/*Create Window*/
	window.setSize(300,300);
	window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	window.setLayout(new GridLayout(3,3));
	
	/*Add Buttons To The Window*/
	window.add(button1);
	window.add(button2);
	window.add(button3);
	window.add(button4);
	window.add(button5);
	window.add(button6);
	window.add(button7);
	window.add(button8);
	window.add(button9);
	
	/*Add The Action Listener To The Buttons*/
	button1.addActionListener(this);
	button2.addActionListener(this);
	button3.addActionListener(this);
	button4.addActionListener(this);
	button5.addActionListener(this);
	button6.addActionListener(this);
	button7.addActionListener(this);
	button8.addActionListener(this);
	button9.addActionListener(this);
	
	/*Make The Window Visible*/
	window.setVisible(true);
	}
	
	public void actionPerformed(ActionEvent a) {
		
		/*Display X's or O's on the buttons*/
		if(a.getSource() == button1){
			button1.setText("X");
		} else if(a.getSource() == button2){
			button2.setText("X");
		} else if(a.getSource() == button3){
			button3.setText("X");
		} else if(a.getSource() == button4){
			button4.setText("X");
		} else if(a.getSource() == button5){
			button5.setText("X");
		} else if(a.getSource() == button6){
			button6.setText("X");
		} else if(a.getSource() == button7){
			button7.setText("X");
		} else if(a.getSource() == button8){
			button8.setText("X");
		} else if(a.getSource() == button9){
			button9.setText("X");
		}
	}
	
	public static void main(String[] args){
		new TicTacToeV1();
	}
}

The next problem I had to surmount was to determine whose turn it was. I did this by creating a hidden variable that increments each time a button is pressed.

Code:

 package mytictactoe;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;


public class TicTacToeV1 implements ActionListener {
	/*Instance Variables*/
	private JFrame window = new JFrame("Tic-Tac-Toe");
	private JButton button1 = new JButton("");
	private JButton button2 = new JButton("");
	private JButton button3 = new JButton("");
	private JButton button4 = new JButton("");
	private JButton button5 = new JButton("");
	private JButton button6 = new JButton("");
	private JButton button7 = new JButton("");
	private JButton button8 = new JButton("");
	private JButton button9 = new JButton("");
	private String letter = "";
	private int count = 0;
	
	public TicTacToeV1(){
	/*Create Window*/
	window.setSize(300,300);
	window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	window.setLayout(new GridLayout(3,3));
	
	/*Add Buttons To The Window*/
	window.add(button1);
	window.add(button2);
	window.add(button3);
	window.add(button4);
	window.add(button5);
	window.add(button6);
	window.add(button7);
	window.add(button8);
	window.add(button9);
	
	/*Add The Action Listener To The Buttons*/
	button1.addActionListener(this);
	button2.addActionListener(this);
	button3.addActionListener(this);
	button4.addActionListener(this);
	button5.addActionListener(this);
	button6.addActionListener(this);
	button7.addActionListener(this);
	button8.addActionListener(this);
	button9.addActionListener(this);
	
	/*Make The Window Visible*/
	window.setVisible(true);
	}
	
	public void actionPerformed(ActionEvent a) {
		count++;
		
		/*Calculate Who's Turn It Is*/
		if(count == 1 || count == 3 || count == 5 || count == 7 || count == 9){
		letter = "X";
		} else if(count == 2 || count == 4 || count == 6 || count == 8 || count == 10){
		letter = "O";
		}
		
		/*Display X's or O's on the buttons*/
		if(a.getSource() == button1){
			button1.setText(letter);
		} else if(a.getSource() == button2){
			button2.setText(letter);
		} else if(a.getSource() == button3){
			button3.setText(letter);
		} else if(a.getSource() == button4){
			button4.setText(letter);
		} else if(a.getSource() == button5){
			button5.setText(letter);
		} else if(a.getSource() == button6){
			button6.setText(letter);
		} else if(a.getSource() == button7){
			button7.setText(letter);
		} else if(a.getSource() == button8){
			button8.setText(letter);
		} else if(a.getSource() == button9){
			button9.setText(letter);
		}
	}
	
	public static void main(String[] args){
		new TicTacToeV1();
	}
}

The count integer increments by one each time a button is clicked. I also created a letter string that would vary depending on count’s value. If count is 1,3,5,7 or 9 letter is defined as X if count is 2,4,6,8 or 10 count is defined as O. I found out that even if a button is pressed, the button is still active causing the button to change to both O and X. Setting the setEnable() method to false fixed this.

Code:

 package mytictactoe;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;


public class TicTacToeV1 implements ActionListener {
	/*Instance Variables*/
	private JFrame window = new JFrame("Tic-Tac-Toe");
	private JButton button1 = new JButton("");
	private JButton button2 = new JButton("");
	private JButton button3 = new JButton("");
	private JButton button4 = new JButton("");
	private JButton button5 = new JButton("");
	private JButton button6 = new JButton("");
	private JButton button7 = new JButton("");
	private JButton button8 = new JButton("");
	private JButton button9 = new JButton("");
	private String letter = "";
	private int count = 0;
	
	public TicTacToeV1(){
	/*Create Window*/
	window.setSize(300,300);
	window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	window.setLayout(new GridLayout(3,3));
	
	/*Add Buttons To The Window*/
	window.add(button1);
	window.add(button2);
	window.add(button3);
	window.add(button4);
	window.add(button5);
	window.add(button6);
	window.add(button7);
	window.add(button8);
	window.add(button9);
	
	/*Add The Action Listener To The Buttons*/
	button1.addActionListener(this);
	button2.addActionListener(this);
	button3.addActionListener(this);
	button4.addActionListener(this);
	button5.addActionListener(this);
	button6.addActionListener(this);
	button7.addActionListener(this);
	button8.addActionListener(this);
	button9.addActionListener(this);
	
	/*Make The Window Visible*/
	window.setVisible(true);
	}
	
	public void actionPerformed(ActionEvent a) {
		count++;
		
		/*Calculate Who's Turn It Is*/
		if(count == 1 || count == 3 || count == 5 || count == 7 || count == 9){
		letter = "X";
		} else if(count == 2 || count == 4 || count == 6 || count == 8 || count == 10){
		letter = "O";
		}
		
		/*Display X's or O's on the buttons*/
		if(a.getSource() == button1){
			button1.setText(letter);
			button1.setEnabled(false);
		} else if(a.getSource() == button2){
			button2.setText(letter);
			button2.setEnabled(false);
		} else if(a.getSource() == button3){
			button3.setText(letter);
			button3.setEnabled(false);
		} else if(a.getSource() == button4){
			button4.setText(letter);
			button4.setEnabled(false);
		} else if(a.getSource() == button5){
			button5.setText(letter);
			button5.setEnabled(false);
		} else if(a.getSource() == button6){
			button6.setText(letter);
			button6.setEnabled(false);
		} else if(a.getSource() == button7){
			button7.setText(letter);
			button7.setEnabled(false);
		} else if(a.getSource() == button8){
			button8.setText(letter);
			button8.setEnabled(false);
		} else if(a.getSource() == button9){
			button9.setText(letter);
			button9.setEnabled(false);
		}

	}
	
	public static void main(String[] args){
		new TicTacToeV1();
	}
}

Now we need to determine the winner. I created some logical statements to determine each possible case of winning. Ecentially if button1, button2, and button3 were all the same value, that person won, but you also have to account for the fact that when the program starts each button is null causing the winner to be null. However null is not a player and in your logical statements you must account for this. I created a Boolean win instance variable set to false by default and then added these logical statements to my actionPerformed method.

Code:

if( button1.getText() == button2.getText() && button2.getText() == button3.getText() && button1.getText() != ""){
	win = true;
}
else if(button4.getText() == button5.getText() && button5.getText() == button6.getText() && button4.getText() != ""){
	win = true;
}
else if(button7.getText() == button8.getText() && button8.getText() == button9.getText() && button7.getText() != ""){
	win = true;
}
		
//virticle wins
else if(button1.getText() == button4.getText() && button4.getText() == button7.getText() && button1.getText() != ""){
	win = true;
}
else if(button2.getText() == button5.getText() && button5.getText() == button8.getText() && button2.getText() != ""){
	win = true;
}
else if(button3.getText() == button6.getText() && button6.getText() == button9.getText() && button3.getText() != ""){
	win = true;
}
		
//diagonal wins
else if(button1.getText() == button5.getText() && button5.getText() == button9.getText() && button1.getText() != ""){
	win = true;
}
else if(button3.getText() == button5.getText() && button5.getText() == button7.getText() && button3.getText() != ""){
	win = true;
}
else {
	win = false;
}

Which accounts for every possible win. Now that we have determined the winner, lets add a popup box announcing the winner. All we have to do is create a if statement and if there is a winner announce it, if there is no winner after nine clicks announce there is a tie. To create a popup box we are going to use showMessageDialog provided to us in the JOptionPane package.

Code:

if(win == true){
	JOptionPane.showMessageDialog(null, letter + " WINS!");
} else if(count == 9 && win == false){
	JOptionPane.showMessageDialog(null, "Tie Game!");
}

My final code looks like this:

Code:

 package mytictactoe;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;


public class TicTacToeV1 implements ActionListener {
	/*Instance Variables*/
	private JFrame window = new JFrame("Tic-Tac-Toe");
	private JButton button1 = new JButton("");
	private JButton button2 = new JButton("");
	private JButton button3 = new JButton("");
	private JButton button4 = new JButton("");
	private JButton button5 = new JButton("");
	private JButton button6 = new JButton("");
	private JButton button7 = new JButton("");
	private JButton button8 = new JButton("");
	private JButton button9 = new JButton("");
	private String letter = "";
	private int count = 0;
	private boolean win = false;
	
	public TicTacToeV1(){
	/*Create Window*/
	window.setSize(300,300);
	window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	window.setLayout(new GridLayout(3,3));
	
	/*Add Buttons To The Window*/
	window.add(button1);
	window.add(button2);
	window.add(button3);
	window.add(button4);
	window.add(button5);
	window.add(button6);
	window.add(button7);
	window.add(button8);
	window.add(button9);
	
	/*Add The Action Listener To The Buttons*/
	button1.addActionListener(this);
	button2.addActionListener(this);
	button3.addActionListener(this);
	button4.addActionListener(this);
	button5.addActionListener(this);
	button6.addActionListener(this);
	button7.addActionListener(this);
	button8.addActionListener(this);
	button9.addActionListener(this);
	
	/*Make The Window Visible*/
	window.setVisible(true);
	}
	
	public void actionPerformed(ActionEvent a) {
		count++;
		
		/*Calculate Who's Turn It Is*/
		if(count == 1 || count == 3 || count == 5 || count == 7 || count == 9){
		letter = "X";
		} else if(count == 2 || count == 4 || count == 6 || count == 8 || count == 10){
		letter = "O";
		}
		
		/*Display X's or O's on the buttons*/
		if(a.getSource() == button1){
			button1.setText(letter);
			button1.setEnabled(false);
		} else if(a.getSource() == button2){
			button2.setText(letter);
			button2.setEnabled(false);
		} else if(a.getSource() == button3){
			button3.setText(letter);
			button3.setEnabled(false);
		} else if(a.getSource() == button4){
			button4.setText(letter);
			button4.setEnabled(false);
		} else if(a.getSource() == button5){
			button5.setText(letter);
			button5.setEnabled(false);
		} else if(a.getSource() == button6){
			button6.setText(letter);
			button6.setEnabled(false);
		} else if(a.getSource() == button7){
			button7.setText(letter);
			button7.setEnabled(false);
		} else if(a.getSource() == button8){
			button8.setText(letter);
			button8.setEnabled(false);
		} else if(a.getSource() == button9){
			button9.setText(letter);
			button9.setEnabled(false);
		}
		
		/*Determine who won*/
		//horizontal wins
		if( button1.getText() == button2.getText() && button2.getText() == button3.getText() && button1.getText() != ""){
			win = true;
		}
		else if(button4.getText() == button5.getText() && button5.getText() == button6.getText() && button4.getText() != ""){
			win = true;
		}
		else if(button7.getText() == button8.getText() && button8.getText() == button9.getText() && button7.getText() != ""){
			win = true;
		}
		
		//virticle wins
		else if(button1.getText() == button4.getText() && button4.getText() == button7.getText() && button1.getText() != ""){
			win = true;
		}
		else if(button2.getText() == button5.getText() && button5.getText() == button8.getText() && button2.getText() != ""){
			win = true;
		}
		else if(button3.getText() == button6.getText() && button6.getText() == button9.getText() && button3.getText() != ""){
			win = true;
		}
		
		//diagonal wins
		else if(button1.getText() == button5.getText() && button5.getText() == button9.getText() && button1.getText() != ""){
			win = true;
		}
		else if(button3.getText() == button5.getText() && button5.getText() == button7.getText() && button3.getText() != ""){
			win = true;
		}
		else {
			win = false;
		}
		
		/*Show a dialog if someone wins or the game is tie*/
		if(win == true){
			JOptionPane.showMessageDialog(null, letter + " WINS!");
		} else if(count == 9 && win == false){
			JOptionPane.showMessageDialog(null, "Tie Game!");
		}
	}
	
	public static void main(String[] args){
		new TicTacToeV1();
	}
}

In a future tutorial I will clean up this code as there is a lot of unneeded repetition and I may even add AI for a single user to play.

***John*** · #2 (**permalink**) 01-11-2007, 02:12 PM

Now in the tutorial above there is a lot of repeated code that can be accounted for by loops an arrays. The first thing I did to make the code more efficient was add the JButtons to an array and loop the array to add the JButton objects to the frame. So lets make an array

Code:

private JButton buttons[] = new JButton[9];

Then replacing the lines that look like this

Code:

private JButton button1 = new JButton("");

and this

Code:

button1.addActionListener(this);

with this

Code:

for(int i=0; i<=8; i++){
	buttons[i] = new JButton();
	window.add(buttons[i]);
	buttons[i].addActionListener(this);
}

Now we've just replaced 27 lines of code with 5. How about making the win conditions more efficient? Well I created an array that listed all the possible win combonations:

Code:

private int[][] winCombinations = new int[][] {
	{0, 1, 2}, {3, 4, 5}, {6, 7, 8}, //horizontal wins
	{0, 3, 6}, {1, 4, 7}, {2, 5, 8}, //virticle wins
	{0, 4, 8}, {2, 4, 6}			 //diagonal wins
};

Rather than creating a condition for each possible win, we can use our winCombinations in conjunction with a loop like so:

Code:

for(int i=0; i<=7; i++){
	if( buttons[winCombinations[i][0]].getText().equals(buttons[winCombinations[i][1]].getText()) && 
		buttons[winCombinations[i][1]].getText().equals(buttons[winCombinations[i][2]].getText()) && 
		buttons[winCombinations[i][0]].getText() != ""){
		win = true;
	}
}

At this point I wasn't satisfied with how I determined who's turn it was. Although there is only a possibility of 4 turns and the code in version 1 works fine, I felt there was a better way to calculate it, and this is what I came up with

Code:

if(count % 2 == 0){
	letter = "O";
} else {
	letter = "X";
}

The % is the remainder operator, meaning if the count value is an even number, when divided by 2 the remainder is 0 which satisfies the first condition, if the number is odd the remainder is 1 causing the condition to branch to the else condition. Finally I came up with a better way to write the X's and O's to the button which looks like this:

Code:

 JButton pressedButton = (JButton)a.getSource(); 
 pressedButton.setText(letter);
 pressedButton.setEnabled(false);

So using a little lateral thinking and making full use of Java's capabilities (loops, arrays, ect...) you can change your code from 140 lines to 80 lines! Here is what my version 2 looks like

Code:

package mytictactoe;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TicTacToeV2 implements ActionListener {
	/*Instance Variables*/
	private int[][] winCombinations = new int[][] {
			{0, 1, 2}, {3, 4, 5}, {6, 7, 8}, //horizontal wins
			{0, 3, 6}, {1, 4, 7}, {2, 5, 8}, //virticle wins
			{0, 4, 8}, {2, 4, 6}			 //diagonal wins
		};
	private JFrame window = new JFrame("Tic-Tac-Toe");
	private JButton buttons[] = new JButton[9];
	private int count = 0;
	private String letter = "";
	private boolean win = false;

	public TicTacToeV2(){
	/*Create Window*/
	window.setSize(300,300);
	window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	window.setLayout(new GridLayout(3,3));
	
	/*Add Buttons To The Window*/
	for(int i=0; i<=8; i++){
		buttons[i] = new JButton();
		window.add(buttons[i]);
		buttons[i].addActionListener(this);
	}
	
	/*Make The Window Visible*/
	window.setVisible(true);
	}
	
	/**
	 When an object is clicked, perform an action.
	 @param a action event object
	 */
	public void actionPerformed(ActionEvent a) {
		count++;
		
		/*Calculate whose turn it is*/
		if(count % 2 == 0){
			letter = "O";
		} else {
			letter = "X";
		}

		/*Write the letter to the button and deactivate it*/
		 JButton pressedButton = (JButton)a.getSource(); 
		 pressedButton.setText(letter);
		 pressedButton.setEnabled(false);
		
		/*Determine who won*/
		for(int i=0; i<=7; i++){
			if( buttons[winCombinations[i][0]].getText().equals(buttons[winCombinations[i][1]].getText()) && 
				buttons[winCombinations[i][1]].getText().equals(buttons[winCombinations[i][2]].getText()) && 
				buttons[winCombinations[i][0]].getText() != ""){
				win = true;
			}
		}
		
		/*Show a dialog when game is over*/
		if(win == true){
			JOptionPane.showMessageDialog(null, letter + " wins the game!");
			System.exit(0);
		} else if(count == 9 && win == false){
			JOptionPane.showMessageDialog(null, "The game was tie!");
			System.exit(0);
		}		
	}
	
	public static void main(String[] args){
		TicTacToeV2 starter = new TicTacToeV2();
	}
}

***John*** · #3 (**permalink**) 01-11-2007, 02:12 PM

I'll explain this code later:

Tic-Tac-Toe with AI

Code:

package mytictactoe;

import java.awt.*;
import java.awt.event.*;
import java.util.Random;

import javax.swing.*;

public class TicTacToeV4 implements ActionListener {
	/*Instance Variables*/
	private int[][] winCombinations = new int[][] {
			{1, 2, 3}, {4, 5, 6}, {7, 8, 9}, //horizontal wins
			{1, 4, 7}, {2, 5, 8}, {3, 6, 9}, //virticle wins
			{1, 5, 9}, {3, 5, 7}			 //diagonal wins
		};
	private JFrame window = new JFrame("Tic-Tac-Toe");
	private JButton buttons[] = new JButton[10];
	private int count = 0;
	private String letter = "";
	private boolean win = false;
	
	public TicTacToeV4(){
	/*Create Window*/
	window.setPreferredSize(new Dimension(300,300));
	window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	window.setLayout(new GridLayout(3,3));
	
	/*Add Buttons To The Window*/
	for(int i = 1; i<=9; i++){
		buttons[i] = new JButton();
		window.add(buttons[i]);
		buttons[i].addActionListener(this);
	}
	
	/*Make The Window Visible*/
	window.setVisible(true);
	window.pack();
	}
	
	public void actionPerformed(ActionEvent a) {


		/*Write the letter to the button and deactivate it*/
		for(int i = 1; i<= 9; i++){
			if(a.getSource() == buttons[i]){
				buttons[i].setText("X");
				buttons[i].setEnabled(false);
			}
		}
		
		count++;		
		AI();

	}
	
	public void AI(){
		count++;
		if(buttons[1].getText().equals("O") && buttons[2].getText().equals("O") && buttons[3].getText().equals("")){
			buttons[3].setText("O");
			buttons[3].setEnabled(false);
		} else if(buttons[4].getText().equals("O") && buttons[5].getText().equals("O") && buttons[6].getText().equals("")){
			buttons[6].setText("O");
			buttons[6].setEnabled(false);
		} else if(buttons[7].getText().equals("O") && buttons[8].getText().equals("O") && buttons[9].getText().equals("")){
			buttons[9].setText("O");
			buttons[9].setEnabled(false);				
		} 
		
		else if(buttons[2].getText().equals("O") && buttons[3].getText().equals("O") && buttons[1].getText().equals("")){
			buttons[1].setText("O");
			buttons[1].setEnabled(false);				
		} else if(buttons[5].getText().equals("O") && buttons[6].getText().equals("O") && buttons[4].getText().equals("")){
			buttons[4].setText("O");
			buttons[4].setEnabled(false);				
		} else if(buttons[8].getText().equals("O") && buttons[9].getText().equals("O") && buttons[7].getText().equals("")){
			buttons[7].setText("O");
			buttons[7].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("O") && buttons[3].getText().equals("O") && buttons[2].getText().equals("")){
			buttons[2].setText("O");
			buttons[2].setEnabled(false);				
		} else if(buttons[4].getText().equals("O") && buttons[6].getText().equals("O") && buttons[5].getText().equals("")){
			buttons[5].setText("O");
			buttons[5].setEnabled(false);				
		} else if(buttons[7].getText().equals("O") && buttons[9].getText().equals("O") && buttons[8].getText().equals("")){
			buttons[8].setText("O");
			buttons[8].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("O") && buttons[4].getText().equals("O") && buttons[7].getText().equals("")){
			buttons[7].setText("O");
			buttons[7].setEnabled(false);				
		} else if(buttons[2].getText().equals("O") && buttons[5].getText().equals("O") && buttons[8].getText().equals("")){
			buttons[4].setText("O");
			buttons[4].setEnabled(false);				
		} else if(buttons[3].getText().equals("O") && buttons[6].getText().equals("O") && buttons[9].getText().equals("")){
			buttons[9].setText("O");
			buttons[9].setEnabled(false);				
		}
		
		else if(buttons[4].getText().equals("O") && buttons[7].getText().equals("O") && buttons[1].getText().equals("")){
			buttons[1].setText("O");
			buttons[1].setEnabled(false);				
		} else if(buttons[5].getText().equals("O") && buttons[8].getText().equals("O") && buttons[2].getText().equals("")){
			buttons[2].setText("O");
			buttons[2].setEnabled(false);				
		} else if(buttons[6].getText().equals("O") && buttons[9].getText().equals("O") && buttons[3].getText().equals("")){
			buttons[3].setText("O");
			buttons[3].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("O") && buttons[7].getText().equals("O") && buttons[4].getText().equals("")){
			buttons[4].setText("O");
			buttons[4].setEnabled(false);				
		} else if(buttons[2].getText().equals("O") && buttons[8].getText().equals("O") && buttons[5].getText().equals("")){
			buttons[5].setText("O");
			buttons[5].setEnabled(false);				
		} else if(buttons[3].getText().equals("O") && buttons[9].getText().equals("O") && buttons[6].getText().equals("")){
			buttons[6].setText("O");
			buttons[6].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("O") && buttons[5].getText().equals("O") && buttons[9].getText().equals("")){
			buttons[9].setText("O");
			buttons[9].setEnabled(false);				
		} else if(buttons[5].getText().equals("O") && buttons[9].getText().equals("O") && buttons[1].getText().equals("")){
			buttons[1].setText("O");
			buttons[1].setEnabled(false);				
		} else if(buttons[1].getText().equals("O") && buttons[9].getText().equals("O") && buttons[5].getText().equals("")){
			buttons[5].setText("O");
			buttons[5].setEnabled(false);				
		}
		
		else if(buttons[3].getText().equals("O") && buttons[5].getText().equals("O") && buttons[7].getText().equals("")){
			buttons[7].setText("O");
			buttons[7].setEnabled(false);				
		} else if(buttons[7].getText().equals("O") && buttons[5].getText().equals("O") && buttons[3].getText().equals("")){
			buttons[3].setText("O");
			buttons[3].setEnabled(false);				
		} else if(buttons[7].getText().equals("O") && buttons[3].getText().equals("O") && buttons[5].getText().equals("")){
			buttons[5].setText("O");
			buttons[5].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("X") && buttons[2].getText().equals("X") && buttons[3].getText().equals("")){
			buttons[3].setText("O");
			buttons[3].setEnabled(false);
		} else if(buttons[4].getText().equals("X") && buttons[5].getText().equals("X") && buttons[6].getText().equals("")){
			buttons[6].setText("O");
			buttons[6].setEnabled(false);				
		} else if(buttons[7].getText().equals("X") && buttons[8].getText().equals("X") && buttons[9].getText().equals("")){
			buttons[9].setText("O");
			buttons[9].setEnabled(false);				
		} 
		
		else if(buttons[2].getText().equals("X") && buttons[3].getText().equals("X") && buttons[1].getText().equals("")){
			buttons[1].setText("O");
			buttons[1].setEnabled(false);				
		} else if(buttons[5].getText().equals("X") && buttons[6].getText().equals("X") && buttons[4].getText().equals("")){
			buttons[4].setText("O");
			buttons[4].setEnabled(false);				
		} else if(buttons[8].getText().equals("X") && buttons[9].getText().equals("X") && buttons[7].getText().equals("")){
			buttons[7].setText("O");
			buttons[7].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("X") && buttons[3].getText().equals("X") && buttons[2].getText().equals("")){
			buttons[2].setText("O");
			buttons[2].setEnabled(false);				
		} else if(buttons[4].getText().equals("X") && buttons[6].getText().equals("X") && buttons[5].getText().equals("")){
			buttons[5].setText("O");
			buttons[5].setEnabled(false);				
		} else if(buttons[7].getText().equals("X") && buttons[9].getText().equals("X") && buttons[8].getText().equals("")){
			buttons[8].setText("O");
			buttons[8].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("X") && buttons[4].getText().equals("X") && buttons[7].getText().equals("")){
			buttons[7].setText("O");
			buttons[7].setEnabled(false);				
		} else if(buttons[2].getText().equals("X") && buttons[5].getText().equals("X") && buttons[8].getText().equals("")){
			buttons[8].setText("O");
			buttons[8].setEnabled(false);				
		} else if(buttons[3].getText().equals("X") && buttons[6].getText().equals("X") && buttons[9].getText().equals("")){
			buttons[9].setText("O");
			buttons[9].setEnabled(false);				
		}
		
		else if(buttons[4].getText().equals("X") && buttons[7].getText().equals("X") && buttons[1].getText().equals("")){
			buttons[1].setText("O");
			buttons[1].setEnabled(false);				
		} else if(buttons[5].getText().equals("X") && buttons[8].getText().equals("X") && buttons[2].getText().equals("")){
			buttons[2].setText("O");
			buttons[2].setEnabled(false);				
		} else if(buttons[6].getText().equals("X") && buttons[9].getText().equals("X") && buttons[3].getText().equals("")){
			buttons[3].setText("O");
			buttons[3].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("X") && buttons[7].getText().equals("X") && buttons[4].getText().equals("")){
			buttons[4].setText("O");
			buttons[4].setEnabled(false);				
		} else if(buttons[2].getText().equals("X") && buttons[8].getText().equals("X") && buttons[5].getText().equals("")){
			buttons[5].setText("O");
			buttons[5].setEnabled(false);				
		} else if(buttons[3].getText().equals("X") && buttons[9].getText().equals("X") && buttons[6].getText().equals("")){
			buttons[6].setText("O");
			buttons[6].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("X") && buttons[5].getText().equals("X") && buttons[9].getText().equals("")){
			buttons[9].setText("O");
			buttons[9].setEnabled(false);				
		} else if(buttons[5].getText().equals("X") && buttons[9].getText().equals("X") && buttons[1].getText().equals("")){
			buttons[1].setText("O");
			buttons[1].setEnabled(false);				
		} else if(buttons[1].getText().equals("X") && buttons[9].getText().equals("X") && buttons[5].getText().equals("")){
			buttons[5].setText("O");
			buttons[5].setEnabled(false);				
		}
		
		else if(buttons[3].getText().equals("X") && buttons[5].getText().equals("X") && buttons[7].getText().equals("")){
			buttons[7].setText("O");
			buttons[7].setEnabled(false);				
		} else if(buttons[7].getText().equals("X") && buttons[5].getText().equals("X") && buttons[3].getText().equals("")){
			buttons[3].setText("O");
			buttons[3].setEnabled(false);				
		} else if(buttons[7].getText().equals("X") && buttons[3].getText().equals("X") && buttons[5].getText().equals("")){
			buttons[5].setText("O");
			buttons[5].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("X") && buttons[5].getText().equals("O") && buttons[9].getText().equals("X")) {
			buttons[6].setText("O");
			buttons[6].setEnabled(false);			
		}	
		
		else if(buttons[3].getText().equals("X") && buttons[5].getText().equals("O") && buttons[7].getText().equals("X")) {
			buttons[4].setText("O");
			buttons[4].setEnabled(false);			
		}
		
		else if(buttons[5].getText().equals("")){
			buttons[5].setText("O");
			buttons[5].setEnabled(false);				
		}
		
		else if(buttons[1].getText().equals("")){
			buttons[1].setText("O");
			buttons[1].setEnabled(false);				
		}
		else {
			if(count >= 9)
				checkWin();
			else
				RandomMove();
		}
		
		checkWin();

	}
	
	public void RandomMove(){
		Random x = new Random();
		int y = 1 + x.nextInt(9);
		if(buttons[y].getText().equals("O") || buttons[y].getText().equals("X") ){
			RandomMove();
		} else {
			buttons[y].setText("O");
			buttons[y].setEnabled(false);
		}
	}
	
	public void checkWin(){ 
			
		/*Determine who won*/
		for(int i=0; i<=7; i++){
			if( buttons[winCombinations[i][0]].getText().equals(buttons[winCombinations[i][1]].getText()) && 
				buttons[winCombinations[i][1]].getText().equals(buttons[winCombinations[i][2]].getText()) && 
				!buttons[winCombinations[i][0]].getText().equals("")) {
				win = true;
			}
		}

		if(count % 2 == 0)
			letter = "O";
		else
			letter = "X";
		
		/*Show a dialog when game is over*/
		if(win == true){
			JOptionPane.showMessageDialog(null, letter + " wins!");
			System.exit(0);
		} else if(count >= 9 && win == false){
			JOptionPane.showMessageDialog(null, "The game was tie!");
			System.exit(0);
		}
	}
	public static void main(String[] args){
		new TicTacToeV4();
	}
}

**WingedPanther** · #4 (**permalink**) 01-11-2007, 02:26 PM

One reason Tic-Tac-Toe is a popular project for CS teachers is because the algorithm for optimal play is well understood. Coding it is slightly trickier

***John*** · #5 (**permalink**) 01-20-2007, 12:37 PM

Quote:

Originally Posted by WingedPanther

One reason Tic-Tac-Toe is a popular project for CS teachers is because the algorithm for optimal play is well understood. Coding it is slightly trickier

Yeah, I didnt have any issues with two player tic-tac-toe, but I am having some issues the AI but that will be fixed in due time.

+++++++++++
Version 2 has been updated.
+++++++++++

Epps · #6 (**permalink**) 02-14-2007, 09:48 PM

Hi, I'm currently in a computer science class and I was using your guide as a reference on how i am making my tic tac toe board but our images on the squares are required to have color....I am unsure of how to do this but i do know that the text that locks each grid is:

pressedButton.setEnabled(false);

any idea on how to get it so there is color on my X's and O's but i can't click on the same button again?

***John*** · #7 (**permalink**) 02-14-2007, 11:15 PM

Java labels support HTML code, so for example in my code, I could do something like this:

Code:

if(count % 2 == 0){
	letter = "<HTML><font color=red>O</font></HTML>";
} else {
	letter = "<HTML><font color=blue>X</font></HTML>";
}

And when an O is suppose to be printed on the JButton it is red and when an X is suppose to be printed on the JButton it is blue. You can also set the background of the JButtons by calling the setBackground(Color c) method, and an example in my code would be

Code:

pressedButton.setBackground(Color.WHITE);

and when the button is pressed it sets the background color to white. This should get you started.

***John*** · #8 (**permalink**) 05-30-2007, 05:56 PM

version 3 added

Bigbag101 · #9 (**permalink**) 06-01-2007, 08:15 PM

hi i also have a programing class and used this method, how abouts would i go adding a picture instead of text?