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

public class SmileKnapper {
    private JFrame vindu;
    private JPanel rutenett;

    public SmileKnapper() {
        vindu = new JFrame("Smilende knapper");
        rutenett = new JPanel(new GridLayout(2, 3));
    }

    public void init() {
        try {
            UIManager.setLookAndFeel(
                UIManager.getCrossPlatformLookAndFeelClassName()
            );
        } catch (Exception e) {
            System.exit(1);
        }

        vindu.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        vindu.setPreferredSize(new Dimension(500, 300));

        for (int i = 1; i <= 6; i++) {
            rutenett.add(new TallKnapp(i + ""));
        }

        vindu.add(rutenett);

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

    private class TallKnapp extends JButton {
        private String tall;

        public TallKnapp(String tall) {
            super(tall);
            this.tall = tall;
            addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    if (getText().equals(":)")) {
                        setText(tall);
                    } else {
                        setText(":)");
                    }
                }
            });
        }
    }

    public static void main(String[] args) {
        SmileKnapper s = new SmileKnapper();
        s.init();
    }
}