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

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Rutenett {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Rutenett");

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        GridLayout layout = new GridLayout(3, 3);
        JPanel panel = new JPanel(layout);

        frame.add(panel);

        for (int i = 0; i < 9; i++) {
            panel.add(new Knapp());
        }

        frame.pack();
        frame.setVisible(true);
    }
}

class Knapp extends JButton {
    
    static int teller = 0;

    class Trykk implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {
            teller++;

                if (teller % 2 == 0) {
                    setText("O");
                }
                else {
                    setText("X");
                }
        }
    }


    Knapp() {
        setText("");
        addActionListener(new Trykk());
    }
}