public class UsoThreads {

public static void main(String[] args) {
    // TODO Auto-generated method stub

    Marco miMarco=new Marco();
    miMarco.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    miMarco.setVisible(true);

}

public Marco() {
    setBounds(400,300,600,400);
    setTitle("Rebota Pelota");
    LaminaPelota miLamina=new LaminaPelota();
    add(miLamina,BorderLayout.CENTER);
    LaminaBotones milamina2=new LaminaBotones();
    add(milamina2,BorderLayout.SOUTH);
}

private double x=10;
private double y=10;
private static final int TAMX=15;
private static final int TAMY=15;
private double speedX=1;
private double speedY=1;

public void mover(Rectangle2D limite) {
    x+=speedX;
    y+=speedY;

    if(x<limite.getMinX()) {
        x=limite.getMinX();
        speedX=-speedX;
    }

    if(x+TAMX>limite.getMaxX()) {
        x=limite.getMaxX()-TAMX;
        speedX=-speedX;
    }

    if(y<limite.getMinY()) {
        y=limite.getMinY();
        speedY=-speedY;
    }

    if(y+TAMY>limite.getMaxY()) {
        y=limite.getMaxY()-TAMY;
        speedY=-speedY;
    }

}

public Ellipse2D dibujarPelota() {
    return new Ellipse2D.Double(x,y,TAMX,TAMY);
}

private ArrayList<Pelota>arrayPelota=new ArrayList<Pelota>();

public void agregarPelota(Pelota b) {
    arrayPelota.add(b);
}

public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2=(Graphics2D) g;

for(Pelota e:arrayPelota) {
    g2.fill(e.dibujarPelota());
}


}

public LaminaBotones() {
    JButton dale=new JButton("Dale");
    JButton salir=new JButton("Salir");
    dale.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub

            comienza();
        }

    });

    salir.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub
            System.exit(0);
        }


    });
    add(dale);
    add(salir);
}

public void comienza() {
    Pelota pelota=new Pelota();
    lamina.agregarPelota(pelota);
    for(int i=1;i<=3000;i++) {
        pelota.mover(lamina.getBounds());
        lamina.paint(lamina.getGraphics());

    }
}

private LaminaPelota lamina;