1. Chapter 8 Frameworks

2. Frameworks Framework is a set of cooperating classes and interface types that structures the essential mechanisms of a particular domain.  Example: Swing is a GUI framework  Framework != design pattern  Typical framework uses multiple design patterns  Inversion of control: framework controls execution flow

3. Example of Frameworks Applets (1) Applet: Java program that runs in a web browser Programmer  forms subclass of Applet or JApplet  overwrites Init start stop destroy paint

4. Example of Frameworks Applets (2) init  Called exactly once, when a class that extends the Applet class.  Purpose: Initialize data structures and add user interface elements start  Called when the applet is first loaded and every time the user restore the browser window containing the applet.  Purpose: Start or restart thread that perform animation or other tasks.

5. Example of Frameworks Applets (3) stop  Called when the user hides the browser window containing the applet and when the browser terminates.  Purpose: Stop thread from updating the applet so computing resources are conserved when the applet is not being viewed. destroy  Called when the browser terminates.  Purpose: Relinquish any resources that were acquired during init or other processing.

6. Example of Frameworks Applets (4) paint  Called when the applet window needs repainting.  Purpose: Redraw the window contents to reflect the current state of the applet data structures.

7. Example of Frameworks Applets (5)

8. Example of Frameworks Applets (6) Sample Source Code: Shows scrolling banner HTML page contains applet tag and parameters

9. Example of Frameworks Applets (7) ch8/applet/BannerApplet.java ch8/applet/BannerApplet.java ch8/applet/BannerApplet.html  init method reads parameters  start/stop start and stop timer  paint paints the applet surface

10. Example of Frameworks Applets (8)