Ejemplo java: VENTANA ActionListener actionPerformed(ActionEvent event)

import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
public class ventana 
{
    public static void main(String [] args)
    {
       AppFrame f = new AppFrame();
       f.setSize(200, 200);
       f.addWindowListener(new WindowAdapter() { public void
           windowClosing(WindowEvent e) {System.exit(0);}});
       f.show();
    }
}
class AppFrame extends Frame implements ActionListener
{
    Button b1, b2;
    labelWindow window;
    AppFrame()
    {
        setLayout(new FlowLayout());
        b1 = new Button("Visualizar la ventana");
        add(b1);
        b1.addActionListener(this);
        b2 = new Button("Ocultar la ventana");
        add(b2);
        b2.addActionListener(this);
        window = new labelWindow(this);
        window.setSize(300, 200);
        window.setLocation(300, 200);
    }
    public void actionPerformed(ActionEvent event)
    {
        if(event.getSource() == b1){
            window.setVisible(true);
        }
        if(event.getSource() == b2){
            window.setVisible(false);
        }
    }
}
class labelWindow extends Window {
    Label label;
    labelWindow(AppFrame af){
        super(af);
        setLayout(new FlowLayout());
        label = new Label("¡Hola desde Java!");
        add(label);
    }
    public void paint (Graphics g)
    {
        int width = getSize().width;
        int height = getSize().height;
        g.drawRect(0, 0, --width, --height);
    }
}