Control Circle ( Enlarge And Shrink )

<br />import java.awt.*;
import java.awt.event.*;
public class ControlCircle extends Frame{
Button btenlarge = new Button("Enlarge");
Button btshrink = new Button("Shrink");
CPanel canvas=new CPanel();
public ControlCircle(){
Panel p = new Panel();
p.add(btenlarge);
p.add(btshrink);

this.add(canvas, BorderLayout.CENTER);
this.add(p, BorderLayout.SOUTH);

btenlarge.addActionListener(new EnlargeListener());
btshrink.addActionListener(new ShrinkListener());
}

public static void main(String[] args) {
Frame f = new ControlCircle();
f.setTitle("ControlCircle1");
f.setSize(200, 200);
f.setVisible(true);
}

class EnlargeListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
canvas.enlarge();
}
}

class ShrinkListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
canvas.shrink();
}
}

class CPanel extends Panel
{
private int radius =5;

public void enlarge() {
radius++;
repaint();
}

public void shrink() {
radius--;
repaint();
}

public void paint(Graphics g) {
super.paint(g);
g.drawOval(getWidth()/2 - radius, getHeight()/2 - radius,2*radius,2*radius);
}
}
}

Output :—