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

public class Rebotador extends Applet implements ActionListener {
private Button iniciar;
public void init() {
iniciar = new Button("Iniciar");
add(iniciar);
iniciar.addActionListener(this);
}

public void actionPerformed(ActionEvent event){
if (event.getSource() == iniciar) {
Graphics g = getGraphics();
Pelota pelota = new Pelota(g);
pelota.mostrar();
}
}
}

class Pelota {
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 Pelota(Graphics graficos) {
g = graficos;
}

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


for (int n = 1; n < 1000; n++) {
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 >= rectSupY)
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");
}
}
}
}