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


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

        boolean harHilst = false;
        JFrame vindu = new JFrame();
        vindu.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JButton knapp = new JButton("");
        JLabel tekst = new JLabel("Hilseknapp");
        
        knapp.add(tekst);
        vindu.add(knapp);

        knapp.addActionListener(new ActionListener() {
            @Override public void actionPerformed(ActionEvent e) {
                if (harHilst){
                    tekst.setText("Ha det!");
                }
                tekst.setText("Hei paa deg!");
            }
        });
        
        vindu.pack(); 
        vindu.setLocationRelativeTo(null); 
        vindu.setVisible(true);
        
        


    }
}