Assignment #1, CS 49J, Section 1

due September 6, 2007
25 points

Please look at the handout regarding assigments on the class web site before submitting your solutions.
Also note that Assignment 2 will be due on September 13, so you might want to start on this one as early as you can.

 

In the file RectangleTester.java that is available by following the link of that name on the class web site, replace the comment

// your code goes here
in the main method by a sequence of instructions that
  1. assigns to r1 a Rectangle of width 80 and height 40 whose top-left corner is at (110,20)
  2. assigns r1 to r2
  3. assigns to r3 a Rectangle of width 240 and height 160 whose top-left corner is at (100,120)
  4. invokes the translate method of the Rectangle class to move r1 20 units down and 40 units to the right
  5. assigns to r4 a new Rectangle with the same width, height, and position as the current value of r1
  6. invokes the translate method on r4 to move it 50 units down and 60 units to the left.

Note that invoking the main method of the RectangleTester class will draw the rectangles in a new window rather than print test results. So for this assignment, you need only submit hard and soft copies of your modified definition; you do not need to turn in a hard copy of your test results. However you should understand why the rectangles appear in the window in the positions they do. Keep in mind that you can use the debugger to inspect the components of any rectangle at any time.

Do not make any changes to any part of the class except for the main method. In particular, for this assignment only, you do not need to write any documentation. But do not remove the documentation that is already present. You might want to run javadoc on the class just to see what HTML documentation gets generated. Recall that this is done through the Project Documentation choice on the Tools menu of the BlueJ window.

You don't need to understand the methods other than main of the class RectangleTester in order to do this assignment. I do recommend that you glance at them, though. These methods are similar to methods given in the last part of Chapter 2 of our textbook.

Finally, do not use this class as an example of good Java style. I have had to make some compromises in order to give you a reasonable assignment so early in our study of Java. In particular, the Rectangle variables should not be instance fields of the class. Also, it would be better if methods other than main did the manipulation of the Rectangle objects, while main invoked these methods to do the testing.