package ticTacToe;

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


public class ticTacToe extends JFrame{
JPanel panel = new JPanel();
XOButton buttons[]=new XOButton[9];

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

}
public ticTacToe()
{
    super("ticTacToe");
    setSize(400,400);
    setResizable(false);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    panel.setLayout(new GridLayout(3,3));
    for(int i=0; i<9; i++)
    {
        buttons[i]=new XOButton();
        panel.add(buttons[i]);
    }
    add(panel);
    setVisible(true);
}
}

package XOButton;

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

public class XOButton extends JButton implements ActionListener{
ImageIcon X,O;
byte value=0;

/*
 * 0:nothing
 * 1:x
 * 2:O
 */

public XOButton()
{
    X=new ImageIcon(this.getClass().getResource("x.png"));
    O=new ImageIcon(this.getClass().getResource("o.png"));
    this.addActionListener(this);

}

public void actionPerformed(ActionEvent e)
{
    value++;
    value%=3;
    switch(value)
    {
    case 0:
        setIcon(null);
        break;
    case 1:
        setIcon(X);
        break;
    case 2:
        setIcon(O);
        break;
    }
}
}