Computer Science 120
Introduction to Programming

Spring 2012, Siena College

MouseDroppings Demo

A working demo of MouseDroppings will appear below. Click inside the applet to interact with it.

MouseDroppings BlueJ Project

Click here to download a BlueJ project for MouseDroppings.

MouseDroppings Source Code

The Java source code for MouseDroppings is below. Click on a file name to download it.

import objectdraw.*;
import java.awt.*;

 * This program causes the mouse to "drop" a red sphere on the canvas each
 * time it is moved.  This demonstrates the use of the "point" parameter
 * for our mouse event handlers.
 * Jim Teresco, Siena College, CSCI 120, Spring 2011
 * $Id: 1496 2011-01-20 20:01:52Z terescoj $

public class MouseDroppings extends WindowController {

    /* drop a small red oval at the point where the mouse just moved */
    public void onMouseMove(Location point) {

	// note that we can attach the setColor to the end
	// of our construction (but only if we are not remembering
	// a name for the object created)
        new FilledOval(point, 10, 10, canvas).setColor(;

    /* clear the canvas if the mouse leaves the window */
    public void onMouseExit(Location point) {