Source Code in This Chapter

Note: right-click or shift-click on the links to download the associated file. All code is freely available for unrestricted use.

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• DriverClass.java Driver template to create and start a Thread object.
• ThreadClass.java Template illustrating the first approach for creating a class with thread behavior. In this approach, the class inherits directly from Thread.
• CounterTest.java Creates and starts three threaded objects which count from 0 to 4. Uses the following class:
  • Counter.java A class that inherits from Thread and defines a run method that counts up to a specified value, pausing for a random time interval in between value counts.
• ThreadedClass.java Template illustrating the second approach for creating a class with thread behavior. In this case, the class implements the Runnable interface while providing a run method for thread execution.
• Counter2Test.java Driver class that creates three threaded objects (Counter2) that count from 0 to 4. In this case, the driver does not start the threads, as each thread is automatically started in Counter2's constructor. Uses the following class:
  • Counter2.java A Runnable that counts to a specified value and sleeps a random number of seconds in between counts. Here, the thread is started automatically when the object is instantiated.
• BuggyCounterApplet.java Demonstrates that data shared by multiple threads is candidate for a potential race condition (i.e., one thread assuming that the data has a particular value, but in reality, the data has been modified by another thread). See BuggyCounterApplet.html (open the Java Console to see that output). Note that you may need to run the applet numerous times before observing the race condition where the two counters are assigned the same label.
• ThreadedRSAKey.java Illustrates converting a method in an existing class from a single-threaded method to a multi-threaded method. In this example, RSAKey computes an RSA public-private key pair, where the key size has a specified number of digits. As large prime numbers require considerable CPU time, ThreadedRSAKey converts the original computeKey method in RSAKey to a multi-threaded method, thus allowing simultaneous (multithreaded) computation of multiple key pairs. Uses the following classes:
  • RSAKey.java Computes RSA public-private key pairs of arbitrary length.
  • Primes.java Generates large prime numbers.
• StoppableThread.java A template to place a thread in a RUN, WAIT, or STOP state.

• Multithreaded Graphics and Double Buffering
  • ShipSimulation.java Illustrates the basic approach of multithreaded graphics whereas a thread adjusts parameters affecting the appearance of the graphics and then calls repaint to schedule an update of the display.
  • DrawCircles.java An applet that draws a circle where the user clicks the mouse. See DrawCircles.html.
    Uses the following class:
    • SimpleCircle.java A class to store the x, y, and radius of a circle. Also, provides a draw method to paint the circle on the graphics object.
  • Rubberband.java Draws a rectangle where one corner is fixed (initial selection of the mouse) and the opposite corner is determined by the location of the dragged mouse. Illustrates drawing directly into the graphics object instead of performing the drawing in the paint method. The graphics object is obtained by calling getGraphics. See Rubberband.html.
  • Bounce.java An applet that contains moving circles that bounce off the walls. Illustrates overriding update to reduce animation flickering and performing incremental updating in the paint method. Here, to achieve animation, a single thread continuously calls repaint while subsequently sleeping for a 100 milliseconds. See Bounce.html. Uses the following classes:
    • MovingCircle.java An extension of SimpleCircle that can be moved about and bounces off walls.
    • SimpleCircle.java A class to store the x, y, and radius of a circle. Also, provides a draw method to paint the circle on the graphics object.
  • DoubleBufferBounce.java An enhancement to the previous applet containing bouncing circles. In this case, double buffering is used to improve the animation; all incremental updating is done in an off-screen image and then the image is drawn to the screen. See DoubleBufferBounce.html. Uses the following classes:
    • MovingCircle.java An extension of SimpleCircle that can be moved about and bounces off walls.
    • SimpleCircle.java A class to store the x, y, and radius of a circle. Also, provides a draw method to paint the circle on the graphics object.
  • ImageAnimation.java Illustrates animation of images by using a thread to cycle through an array of images. See ImageAnimation.html. Uses the following class and images:
    • Duke.java A subclass of Thread holding the images for the animation.
    • Images of Duke. Place in images subdirectory.
      T0.gif, T1.gif, T2.gif, T3.gif, T4.gif, T5.gif, T6.gif, T7.gif, T8.gif, T9.gif, T10.gif, T11.gif, T12.gif, T13.gif, T14.gif (all images in a single zip file).
      Duke^TM is a registered trademark of Sun Microsystems, Inc. All rights apply (http://www.sun.com/policies/trademarks/).
  • TimedAnimation.java An applet that demonstrates animation of an image by using a Timer. Note that Timer is located in the javax.swing package. See TimedAnimation.html (requires Netscape 6.x or a browser that supports Swing). Uses the following classes and images:
    • TimedDuke.java Facilitates animation of Duke images by creating an internal timer.
    • Images of Duke. Place in images subdirectory.
      T0.gif, T1.gif, T2.gif, T3.gif, T4.gif, T5.gif, T6.gif, T7.gif, T8.gif, T9.gif, T10.gif, T11.gif, T12.gif, T13.gif, T14.gif (all images in a single zip file).
      Duke^TM is a registered trademark of Sun Microsystems, Inc. All rights apply (http://www.sun.com/policies/trademarks/).