Checkbox interagir com objeto Java2D (ocultar/desocultar)

import java.awt.*;
import java.awt.geom.*;

import javax.swing.JApplet;


public class DefEx2 extends JApplet {
	public void paint (Graphics screen){

        //desenha a tela principal: 
		Graphics2D screen2D = (Graphics2D) screen;
		setSize(320,300);
		setBackground(Color.blue);
		screen2D.setColor(Color.white);
		BasicStroke pen = new BasicStroke(2F, BasicStroke.CAP_BUTT, BasicStroke.JOIN_ROUND);
		screen2D.setStroke(pen);	
		
		BasicStroke pen2 = new BasicStroke();
		screen2D.setStroke(pen2);
        
        //desenha um label:
		screen2D.setColor(Color.green);
        Font type = new Font("Monospaced",Font.BOLD,16);
        screen2D.setFont(type);                
		screen2D.drawString("Exercício 2", 21, 11);  
		
		//desenha os círculos:
		screen2D.setColor(Color.black);
		Ellipse2D.Float e1 = new Ellipse2D.Float(16,25,50,50);;
		screen2D.fill(e1);
		
		Ellipse2D.Float e2 = new Ellipse2D.Float(75,25,50,50);
		screen2D.fill(e2);		
		
		screen2D.setColor(Color.white);

		Ellipse2D.Float e3 = new Ellipse2D.Float(140,25,50,50);
		screen2D.fill(e3);	
		
		//Desenha os retângulos:
		screen2D.setColor(Color.red);		
		Rectangle2D.Float r1 = new Rectangle2D.Float(16,90,100,50);
		screen2D.fill(r1);
		
		screen2D.setColor(Color.yellow);		
		Rectangle2D.Float r2 = new Rectangle2D.Float(150,90,100,50);
		screen2D.fill(r2);	
		
		//Apresenta a figura:
        Image imagem = getImage(getCodeBase(),"owl.gif");
        screen2D.drawImage(imagem,15,145,this);
	}
}