Java SE (Java Platform, Standard Edition)

Hey all,
I am trying to use a button to trigger an animation on a JPanel. For starters, I want to draw a circle, but when I fire the event, the new circle is not displayed. Here is a toy clone:

JButton button = new JButton("GO");
button.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ae) {
         runFoo();
     }
});

public void runFoo() {
     repaint();
}

public void paintComponent(Graphics g) {
     super.paintComponent(g);
     g.setColor(Color.BLACK);
     g.drawOval(myX, myY, 50,50);
}

Thank you all,
Rob Kallman