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


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");
        vindu.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        vindu.setPreferredSize(new Dimension(400, 500));
        JPanel panel = new JPanel(new GridLayout(2, 3, 10, 10));
        panel.add(new Knapp("1")); 
        panel.add(new Knapp("2")); 
        panel.add(new Knapp("3")); 
        panel.add(new Knapp("4")); 
        panel.add(new Knapp("5")); 
        panel.add(new Knapp("6")); 

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

class Knapp extends JButton{
    private String tall; 

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