CircleDrawer3.java Applet that uses a named nested class to handle mouse events and draw circles. Illustrates third approach to event-handling with listeners: using inner classes.

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

/** Draw circles centered where the user clicks.
 *  Uses named inner classes.
 *  


 ******************

public class CircleDrawer3 extends Applet {
  public void init() {
    setForeground(Color.blue);
    addMouseListener(new CircleListener());
  }

  private class CircleListener extends MouseAdapter {
    private int radius = 25;

    public void mousePressed(MouseEvent event) {
      Graphics g = getGraphics();
      g.fillOval(event.getX()-radius,
                 event.getY()-radius,
                 2*radius,
                 2*radius);
    }
  }
}