Changing the icon of a JButton

Question

So I am trying to create a tic tac toe game that uses the possible slots as buttons. At the start of the game, the buttons are set to a blank white image as their icon. When the button is clicked I am trying to have the button icon change to the corresponding image (x or o), however when a button is clicked the image does not change? Where am I going wrong?

package game;

import java.awt.Color;
import java.awt.Container;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.URL;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingConstants  ;

public class TicTacToe extends JFrame {

private static final String TITLE = "Tic Tac Toe";
private static final int width = 600;
private static final int height = 800;

private Container content;
private JButton exitbutton;
private JButton initbutton;
private JButton[] spaces = new JButton[9];
private CellButtonHandler[] cellHandler = new CellButtonHandler[9];
private InitButtonHandler inithandler;
private ExitButtonHandler exithandler;
private JLabel turn;
private URL base;
private Image o, x, blank;
private Font myfont = new Font("Times New Roman", Font.BOLD, 78);
private ImageIcon icon = new ImageIcon("data/blankButton.png");
private ImageIcon iconx = new ImageIcon("data/x.png");
private ImageIcon icono = new ImageIcon("data/o.gif");

private boolean gameover;
private boolean turnX;

public TicTacToe() {
    setTitle(TITLE);
    setSize(width, height);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setVisible(true);

    content = getContentPane();
    content.setBackground(Color.black);

    content.setLayout(new GridLayout(4, 3));

    for (int i = 0; i < spaces.length; i++) {
        spaces[i] = new JButton();
        cellHandler[i] = new CellButtonHandler();
        spaces[i].addActionListener(cellHandler[i]);
    }

    exitbutton = new JButton("Exit");
    exithandler = new ExitButtonHandler();
    exitbutton.addActionListener(exithandler);
    initbutton = new JButton("Clear");
    inithandler = new InitButtonHandler();
    initbutton.addActionListener(inithandler);

    turn = new JLabel("X's turn", SwingConstants.CENTER);
    turn.setForeground(Color.white);

    for (int i = 0; i < spaces.length; i++) {
        spaces[i].setBackground(Color.white);
        content.add(spaces[i]);
    }

    content.add(initbutton);
    content.add(turn);
    content.add(exitbutton);

    init();
}

public void init() {
    turnX = true;
    gameover = false;
    spaces[0].setIcon(icon);
    spaces[1].setIcon(icon);
    spaces[2].setIcon(icon);
    spaces[3].setIcon(icon);
    spaces[4].setIcon(icon);
    spaces[5].setIcon(icon);
    spaces[6].setIcon(icon);
    spaces[7].setIcon(icon);
    spaces[8].setIcon(icon);

    turn.setText("X's turn");

    setVisible(true);

}

public static void main(String[] args) {
    TicTacToe game = new TicTacToe();
}

private class CellButtonHandler implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        if (gameover) {
            return;
        }

        JButton pressed = (JButton) (e.getSource());

        if (pressed.getIcon().equals(icono) || pressed.getIcon().equals(iconx)) {
            return;
        }

        if (turnX) {
            pressed.setIcon(iconx);
        } else {
            pressed.setIcon(icono);
        }

        if (checkwinnerO()) {
            gameover = true;
            turn.setText("O Wins!");
            } 

        if(checkwinnerX()){
            gameover = true;
            turn.setText("X Wins!");
        }
    }
}

private class ExitButtonHandler implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        System.exit(0);
    }
}

private class InitButtonHandler implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        init();
    }
}

public boolean checkwinnerO() {
    if (spaces[0].getIcon().equals(icono)
            && spaces[1].getIcon().equals(icono) && spaces[2].getIcon().equals(icono)) {
        return true;
    } else if (spaces[3].getIcon().equals(icono)
            && spaces[4].getIcon().equals(icono) && spaces[5].getIcon().equals(icono)) {
        return true;
    } else if (spaces[6].getIcon().equals(icono)
            && spaces[7].getIcon().equals(icono) && spaces[8].getIcon().equals(icono)) {
        return true;
    } else if (spaces[0].getIcon().equals(icono)
            && spaces[3].getIcon().equals(icono) && spaces[6].getIcon().equals(icono)) {
        return true;
    } else if (spaces[1].getIcon().equals(icono)
            && spaces[4].getIcon().equals(icono) && spaces[7].getIcon().equals(icono)) {
        return true;
    } else if (spaces[2].getIcon().equals(icono)
            && spaces[5].getIcon().equals(icono) && spaces[8].getIcon().equals(icono)) {
        return true;
    } else if (spaces[0].getIcon().equals(icono)
            && spaces[4].getIcon().equals(icono) && spaces[8].getIcon().equals(icono)) {
        return true;
    } else if (spaces[2].getIcon().equals(icono)
            && spaces[4].getIcon().equals(icono) && spaces[6].getIcon().equals(icono)) {
        return true;
    } else 

        return false;
}

public boolean checkwinnerX() {
    if (spaces[0].getIcon().equals(iconx)
            && spaces[1].getIcon().equals(iconx) && spaces[2].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[3].getIcon().equals(iconx)
            && spaces[4].getIcon().equals(iconx) && spaces[5].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[6].getIcon().equals(iconx)
            && spaces[7].getIcon().equals(iconx) && spaces[8].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[0].getIcon().equals(iconx)
            && spaces[3].getIcon().equals(iconx) && spaces[6].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[1].getIcon().equals(iconx)
            && spaces[4].getIcon().equals(iconx) && spaces[7].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[2].getIcon().equals(iconx)
            && spaces[5].getIcon().equals(iconx) && spaces[8].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[0].getIcon().equals(iconx)
            && spaces[4].getIcon().equals(iconx) && spaces[8].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[2].getIcon().equals(iconx)
            && spaces[4].getIcon().equals(iconx) && spaces[6].getIcon().equals(iconx)) {
        return true;
    } else 

        return false;

}
}

1. The image icons are initialized.
2. My init method sets each of the buttons icon to the blank image.
3. My CellHandlerMethod handles the change between the blank image and the image (x or o) when clicked.

Answer 1

This output definitely shows a problem with the logic of the game.

Note that it does change from the red square (representing 'blank') to the green circle when the button(s) is(/are) clicked. But it never flips from Player X to Player Y (or vice-versa).

As to why you are not seeing any change, I can only conclude one of 3 things:

1. The images are not where you think they are.
2. The images are not named what you think they are. (E.G. x.png != X.png || x.PNG)
3. The images are not using an internal format understood by Java. Try displaying them directly in a JOptionPane.

Tips

Don't use an ImageIcon to load an image, it does not give feedback. Instead use ImageIO.read(..) which provides lots of helpful feedback.

Source

This is the slightly altered source used. It hot-links to 3 images (so that users of the code can see it work or fail).

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

public class TicTacToe extends JFrame {

private static final String TITLE = "Tic Tac Toe";
private static final int width = 600;
private static final int height = 800;

private Container content;
private JButton exitbutton;
private JButton initbutton;
private JButton[] spaces = new JButton[9];
private CellButtonHandler[] cellHandler = new CellButtonHandler[9];
private InitButtonHandler inithandler;
private ExitButtonHandler exithandler;
private JLabel turn;
private URL base;
private Image o, x, blank;
private Font myfont = new Font("Times New Roman", Font.BOLD, 78);
private ImageIcon icon;
private ImageIcon iconx;
private ImageIcon icono;

private boolean gameover;
private boolean turnX;

public TicTacToe() {
    setTitle(TITLE);
    try {
        URL url = new URL("http://i.stack.imgur.com/F0JHK.png");
        icon = new ImageIcon(url);
        URL urlx = new URL("http://i.stack.imgur.com/T5uTa.png");
        iconx = new ImageIcon(urlx);
        URL urlo = new URL("http://i.stack.imgur.com/yoKxT.png");
        icono = new ImageIcon(urlo);
    } catch (Exception e) {
        e.printStackTrace();
    }
    setSize(width, height);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setVisible(true);

    content = getContentPane();
    content.setBackground(Color.black);

    content.setLayout(new GridLayout(4, 3));

    for (int i = 0; i < spaces.length; i++) {
        spaces[i] = new JButton();
        cellHandler[i] = new CellButtonHandler();
        spaces[i].addActionListener(cellHandler[i]);
    }

    exitbutton = new JButton("Exit");
    exithandler = new ExitButtonHandler();
    exitbutton.addActionListener(exithandler);
    initbutton = new JButton("Clear");
    inithandler = new InitButtonHandler();
    initbutton.addActionListener(inithandler);

    turn = new JLabel("X's turn", SwingConstants.CENTER);
    turn.setForeground(Color.white);

    for (int i = 0; i < spaces.length; i++) {
        spaces[i].setBackground(Color.white);
        content.add(spaces[i]);
    }

    content.add(initbutton);
    content.add(turn);
    content.add(exitbutton);

    init();
}

public void init() {
    turnX = true;
    gameover = false;
    spaces[0].setIcon(icon);
    spaces[1].setIcon(icon);
    spaces[2].setIcon(icon);
    spaces[3].setIcon(icon);
    spaces[4].setIcon(icon);
    spaces[5].setIcon(icon);
    spaces[6].setIcon(icon);
    spaces[7].setIcon(icon);
    spaces[8].setIcon(icon);

    turn.setText("X's turn");

    setVisible(true);

}

public static void main(String[] args) {
    TicTacToe game = new TicTacToe();
}

private class CellButtonHandler implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        if (gameover) {
            return;
        }

        JButton pressed = (JButton) (e.getSource());

        if (pressed.getIcon().equals(icono) || pressed.getIcon().equals(iconx)) {
            return;
        }

        if (turnX) {
            pressed.setIcon(iconx);
        } else {
            pressed.setIcon(icono);
        }

        if (checkwinnerO()) {
            gameover = true;
            turn.setText("O Wins!");
            }

        if(checkwinnerX()){
            gameover = true;
            turn.setText("X Wins!");
        }
    }
}

private class ExitButtonHandler implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        System.exit(0);
    }
}

private class InitButtonHandler implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        init();
    }
}

public boolean checkwinnerO() {
    if (spaces[0].getIcon().equals(icono)
            && spaces[1].getIcon().equals(icono) && spaces[2].getIcon().equals(icono)) {
        return true;
    } else if (spaces[3].getIcon().equals(icono)
            && spaces[4].getIcon().equals(icono) && spaces[5].getIcon().equals(icono)) {
        return true;
    } else if (spaces[6].getIcon().equals(icono)
            && spaces[7].getIcon().equals(icono) && spaces[8].getIcon().equals(icono)) {
        return true;
    } else if (spaces[0].getIcon().equals(icono)
            && spaces[3].getIcon().equals(icono) && spaces[6].getIcon().equals(icono)) {
        return true;
    } else if (spaces[1].getIcon().equals(icono)
            && spaces[4].getIcon().equals(icono) && spaces[7].getIcon().equals(icono)) {
        return true;
    } else if (spaces[2].getIcon().equals(icono)
            && spaces[5].getIcon().equals(icono) && spaces[8].getIcon().equals(icono)) {
        return true;
    } else if (spaces[0].getIcon().equals(icono)
            && spaces[4].getIcon().equals(icono) && spaces[8].getIcon().equals(icono)) {
        return true;
    } else if (spaces[2].getIcon().equals(icono)
            && spaces[4].getIcon().equals(icono) && spaces[6].getIcon().equals(icono)) {
        return true;
    } else

        return false;
}

public boolean checkwinnerX() {
    if (spaces[0].getIcon().equals(iconx)
            && spaces[1].getIcon().equals(iconx) && spaces[2].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[3].getIcon().equals(iconx)
            && spaces[4].getIcon().equals(iconx) && spaces[5].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[6].getIcon().equals(iconx)
            && spaces[7].getIcon().equals(iconx) && spaces[8].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[0].getIcon().equals(iconx)
            && spaces[3].getIcon().equals(iconx) && spaces[6].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[1].getIcon().equals(iconx)
            && spaces[4].getIcon().equals(iconx) && spaces[7].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[2].getIcon().equals(iconx)
            && spaces[5].getIcon().equals(iconx) && spaces[8].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[0].getIcon().equals(iconx)
            && spaces[4].getIcon().equals(iconx) && spaces[8].getIcon().equals(iconx)) {
        return true;
    } else if (spaces[2].getIcon().equals(iconx)
            && spaces[4].getIcon().equals(iconx) && spaces[6].getIcon().equals(iconx)) {
        return true;
    } else

        return false;
}
}