Problema com OvalPanel();

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

public class Elipse extends JFrame{
    private JSlider diametroSlider;
    private OvalPanel meuPanel;
    
    public Elipse(){
        super("Elipse");
        
        meuPanel = new OvalPanel();
        meuPanel.setBackground(Color.YELLOW);
        
        diametroSlider = new JSlider(SwingConstants.HORIZONTAL,0,200,10);
        diametroSlider.setMajorTickSpacing(10);
        diametroSlider.setPaintTicks(true);
        
        diametroSlider.addChangeListener(
                new ChangeListener(){
                    public void stateChanged(ChangeEvent e)
                    {
                        meuPanel.setDiameter(diametroSlider.getValue());
                    }
        }
     );
     
     Container container = getContentPane();
     container.add(diametroSlider, BorderLayout.SOUTH);
     container.add(meuPanel, BorderLayout.CENTER);
     
     setSize(220,270);
     setVisible(true);
     
    }
    
    public static void main (String args[]){
        
        Elipse aplicacao = new Elipse();
        aplicacao.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}