import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;

public class Rebotador3 extends Applet implements ActionListener{

private Button iniciar, detener;
private Pelota3 pelota;

public void init() {
iniciar = new Button("Iniciar");
add(iniciar);
iniciar.addActionListener(this);
detener = new Button("Detener");
add(detener);
detener.addActionListener(this);
}

public void actionPerformed(ActionEvent event){
if(event.getSource() == iniciar){
Graphics g = getGraphics();
pelota = new Pelota3(g);
pelota.start();
}
if(event.getSource() == detener)
pelota.porFavorDetente();
}
}

class Pelota3 extends Thread{

private boolean seguirRebotando;
private Graphics g;
private int x = 7, xCambio = 7;
private int y = 0, yCambio = 2;
private int diametro = 10;
private int rectIzqX = 0, rectDerX = 100;
private int rectSupY = 0, rectInfY = 100;

public Pelota3(Graphics graficos){
g = graficos;
seguirRebotando = true;
}

public void porFavorDetente(){
seguirRebotando = false;
}

public void run(){
g.drawRect(rectIzqX, rectSupY,
rectDerX - rectIzqX + 10, rectInfY - rectSupY + 10);

while(seguirRebotando){
g.setColor(Color.white);
g.fillOval(x, y, diametro, diametro);
if (x + xCambio <= rectIzqX)
xCambio = -xCambio;
if (x + xCambio <= rectDerX)
xCambio = -xCambio;

if (y + yCambio <= rectSupY)
yCambio = -yCambio;
if (y + yCambio <= rectInfY)
yCambio = -yCambio;

x = x + xCambio;
y = y + yCambio;

g.setColor(Color.red);
g.fillOval(x, y, diametro, diametro);

try{
Thread.sleep(50);
}
catch(InterruptedException e){
System.err.println("excepcion de inactividad");
}
}
}
}