Due: Monday, February 3, 4 PM (in class).

This is a warmup exercise to introduce you to GUI programming - how to construct a display (GUI syntax - the composite design pattern) and how to program window actions (GUI semantics - the observer design pattern). We'll also gently introduce UML.

The relevant material is covered in Jia (Sections 2.2, 2.3.1, 8.3, 9.1 and 9.2).

Here's a partial solution.

• Apply for a CS680 account on the Department's unix system.

• Get the textbooks for the course. (You will need Jia right away.)

• You will find the source code for version 1 of the scribble application in Chapter 9 of Jia in directory $CS680/hw1/scribblesource (I retyped it from the text since Jia's website was temporarily down.) Copy, compile and run it. You will have to get the Java package/directory conventions right to do this - read about it in Jia, starting on page 134.

• UML for static structures. Analyze Figure 9.2 using the vocabulary from chapter 2 on UML class diagrams. Explain why some lines are solid while others are dashed, why some end with diamonds, some with arrowheads, some with nothing.

• UML for dynamic behavior. Draw a UML sequence diagram for a scribble mouse drag.

• Modify the scribble application so that it puts up two canvases to scribble on, side by side. Each canvas should have a button beneath it labelled "clear". Clicking the button should clear that canvas. Here's a picture of what you might write. (You don't have to get the colors and sizes to match.)

  Draw a UML class diagram for your version of scribble.

  Your source code

  • must be well designed - if you simply add some lines of code to make the application work, look at what you've done and think "that's pretty ugly - not how I would have done it if I'd started from scratch" - them reorganize your code. Don't be afraid to design new classes.
  • must honor formatting conventions - either Jia's, or your own (note that I changed some of Jia's code when I retyped it).
  • should have no duplicated code (don't program by cutting a block of java, pasting it somewhere else and just changing a token or two).
  • should indicate clearly where you have modified Jia's code and where it is unchanged.

• hard copy of the answers to the questions asked,
• hard copy of your Java source code, and
• a memo discussing your design and coding process. Where did you encounter problems? How did you solve them? What did you learn?

If you can, make screen captures showing your new GUI.

Leave source code in a hw1 subdirectory of your cs680 course directory. Do not alter any permissions.