import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
  
public class ControlCircle extends JFrame {
  private JButton jbtEnlarge = new JButton("Enlarge");
  private JButton jbtShrink = new JButton("Shrink");
  private CirclePanel canvas = new CirclePanel();
    
  public ControlCircle() {
    JPanel panel = new JPanel(); // Use the panel to group buttons
    panel.add(jbtEnlarge);
    panel.add(jbtShrink);
      
    this.add(canvas, BorderLayout.CENTER); // Add canvas to center
    this.add(panel, BorderLayout.SOUTH); // Add buttons to the frame 
      
    jbtEnlarge.addActionListener(new EnlargeListener());
  }
    
  /** Main method */
  public static void main(String[] args) {
    JFrame frame = new ControlCircle();
    frame.setTitle("ControlCircle");
    frame.setLocationRelativeTo(null); // Center the frame
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(200, 200);
    frame.setVisible(true);
  }
   
  class EnlargeListener implements ActionListener { // Inner class
     @Override
     public void actionPerformed(ActionEvent e) {
       canvas.enlarge();
     }
  }
    
  class CirclePanel extends JPanel { // Inner class
    private int radius = 5; // Default circle radius
        
    /** Enlarge the circle */
    public void enlarge() {
      radius++;
      repaint();
    }
      
    @Override 
    protected void paintComponent(Graphics g) {
      super.paintComponent(g);
      g.drawOval(getWidth() / 2 - radius, getHeight() / 2 - radius, 
        2 * radius, 2 * radius);
    }
  }   
}