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

public class Oppgave1 {
    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(
                UIManager.getCrossPlatformLookAndFeelClassName()
            );
        } catch (Exception e) {
            System.exit(-1);
        }

        JFrame vindu = new JFrame("Oppgave 1 lag et rutenett");
        vindu.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel();
        vindu.add(panel);

        lagRutenett(panel, 2, 3);

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

    public static void lagRutenett(JPanel panel, int rader, int kolonner) {
        panel.setLayout(new GridLayout(rader, kolonner));
        for (int i = 0; i < rader * kolonner; i++) {
            panel.add(new RuteKnapp(i + ""));
        }
    }
}

class RuteKnapp extends JButton {
    private String tall;
    private boolean erTrykket = false;

    public RuteKnapp(String tall) {
        super(tall);
        this.tall = tall;
        settOppGUI();
    }

    public void settOppGUI() {
        addActionListener(new SkiftTegn()); 
    }

    class SkiftTegn implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            if (erTrykket) {
                setText(tall);
            } else {
                setText(":)");
            }
            erTrykket = !erTrykket;
        }
    }
}