XOR Painting issue in java

I have a problem with java Xor method:

public class Okno extends JFrame {

public static void main(String[] args) {
    Okno okno = new Okno();
}


Window()
{
    this.setSize(300,300);
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);
    JButton button= new JButton("Circle");
    button.addActionListener(
    new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
         开发者_开发问答   Graphics2D g = (Graphics2D)Window.this.getGraphics();
            g.setXORMode(Color.red);
            g.setStroke(new BasicStroke(10));
            g.drawOval(100, 100, 100, 100);
        }
    });

    this.add("South",button);
    this.setVisible(true);
}

It paints circle after second click on button. On Graphic from Image it works fine...

---

If the code works the second time, odds are good you are calling the code incorrectly. For example, you may be requesting a paint callback and then improperly invalidating the screen area, which means that while the view has changed, the is no event to start the repainting routines.

On the second button click, the paint will then detect the first button click's action, which was to change what is drawn.

Swing painting has changed slightly over the years. You might be stuck with an old tutorial or text. Take a look at the latest online offerings to get a good idea of how it should be done.