Assignment 2

This assignment is to be handwritten in pen. It does not need to be submitted electronically.

Due: Week of October 2^nd 2000, beginning of your tutorial or lab.

The late policy for handwritten submissions differs from the late policy for electronic submissions. See your course information sheet for more details.

Part One

In contrast to part one in Assignment 1, which asks you to fill in the missing code for the comments that are given, for part one of Assignment 2 you must fill in the missing comments for the lines of code that are given.

The program for this part contains the following three java files, which are available on the course web site: Shapes.java, Rectangle.java, and Cylinder.java. You will need to add the missing comments to the main method of the Shapes class. Lines that require you to add comments begin with // but do not contain any text. Print out the Shapes.java file and add your comments to the printout by hand.

To determine what to write in the comments for a given method call, first locate the definition of the method that is being called. To describe the method call and the arguments that are being passed to the method, use the same wording that has been used in the comments for the definition of the method. Use the method call for box.init(10,20,"red"), which has been commented for you, as an example.

Part Two

For this part, you are required to update pictures of the memory model as taught during your lectures. You are given a Java program which is made up of the files Warehouse.java, Supplier.java, and Item.java. You are also provided with a diagram of the memory model that results after statement 4 in the main method has completed execution. Your task is to update the memory model (only updates to the "Method Stack" and "Object Space" are required) at the three stages that are described below.

Since Strings are objects, they should be stored by reference and each String should correspond to a different object. To simplify the pictures of the memory model, we will cheat a little and store Strings directly instead, just as we store primitive types, such as integers.

Update A

Update the memory model diagram above to show the state of the diagram after statement 6 of the main() method finishes executing.

Update B

Update the memory model diagram above to show the state of the diagram after statement 2 of the addStock() method finishes executing the first time that it executes. This is initiated by the call in statement 7 of the main method.

Update C

Update the memory model diagram above to show the state of the diagram after statement 2 of the getSummary() method in the Supplier class finishes executing the first time that it executes. This is initiated by the call in statement 13 of the main method.

Submission

No electronic submission is required for this assignment. Be sure to completely fill out and attach the assignment cover sheet that is available on the course web site.

For part one, hand in a printout of Shapes.java, with your handwritten comments added in pen. Please make sure that your comments are legible.

For part two, hand in a printout of this handout, with the three memory model diagrams updated by hand using pen. Be sure to clearly indicate values that have changed, by crossing out the old value, and clearly labelling the new value.