Problema exemplo livro Deitel

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

public class CustomPanelTest extends JFrame {
  private JPanel buttonPanel;
  private CustomPanelTest myPanel;
  private JButton circle,square;

  public CustomPanelTest() {
    super ("CustomPanel Test");
    myPanel = new CustomPanelTest();
    myPanel.setBackground(Color.green);

    square = new JButton("Square");
    square.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
		myPanel.draw(CustomPanel.SQUARE);
      }
    });

    circle = new JButton("Circle");
    circle.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        myPanel.draw(CustomPanel.CIRCLE);
      }
    });

    buttonPanel = new JPanel();
    buttonPanel.setLayout(new GridLayout(1,2));
    buttonPanel.add(circle);
    buttonPanel.add(square);

    Container c = getContentPane();
    c.add(myPanel,BorderLayout.CENTER);
    c.add(buttonPanel,BorderLayout.SOUTH);

    setSize(300,150);
    show();
  }

  public static void main(String args[]) {
    CustomPanelTest app = new CustomPanelTest();

    app.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
  }
}