| 
CSE 142 Winter 2003 -- Homework #2 |
|
 UW Home |
CSE Home |
Message
Board |
Contact Info |
|
|
CSE 142 Homework #2Due: Wednesday, January 22 at 9:00 PM. No late assignments will be accepted.Directions: Please answer the following questions. Use full sentences when answering questions that require explanations. Remember to acknowledge any help you receive from individuals outside the course staff. These questions are based on material from lecture and from Chapter 2 thru Chapter 5 in the textbook.You answers should be formated using Microsoft Word or WordPad (.doc file),
Notepad or any plain text editor (.txt), or any other file format that
can be read by recent versions of Microsoft Word. When you are done, use
this turnin form to submit your assignment over
the web. If you make a mistake, you can resubmit your assignment as often
as needed. We will grade the last one that you hand in. Your graded assignment
will be returned to you via email. Please include the questions along
with your answers in your homework file. Remember to get started right away. Don't wait until Wednesday after dinner
to begin, or you are likely not to finish on time. Grading Guidelines: Unless indicated otherwise, each question or part
of a question is worth 2 points. To gain the full 2 points, your answer must
have
no significant
flaws, must be clear to the reader, and must be complete (but remember
that complete does not mean verbose - be concise and to the point).
One point will be awarded to answers that are partially correct,
are somewhat unclear, or are incomplete. You must show credible
effort to gain at least one point per question. 1. Suppose you want to model a system to manage a university library's holdings. Give two examples of classes you would design for this system. In your class description, include at least five properties for these classes. You do not need to draw the boxes. An underscored class name followed by a list of properties is fine. 2. [based on Chapter 3] For question 1, you designed the properties of two classes. Suggest reasonable identifiers for each of these properties. Give examples of inappropriate identifiers for each property and state why the identifiers are inappropriate. 3. [Adapted from Exercise 2.9] Could an object representing a student
in a registration system be used to model a user of a university library
system? Are all properties of a student relevant for a library user? If not,
which properties wouldn't you model for students in a library system? Are
new properties needed for a library user? If so, name these new properties. 4. [4 Points] Design classes to model interactions with a library system. First, design the class for Library User, specifying the properties of the class. You may want to design other classes in order to have properties reference other objects. Think about what books or journals you have checked out at the moment, their due dates, and the properties you used to model a Library User. To keep things simple, assume a library user can have at most 5 items checked out at any one time. Draw object diagrams [See page 41 in the text to see examples of object diagrams] to represent yourself as a library user, what you have checked out, and when your items are due. Remember, properties of objects can reference other objects. Do your best to create diagrams. The Paint program that comes as an accessory with Windows allows you to draw simple diagrams. You can create a file of the diagram and paste this diagram into your homework file. If you currently have no books or journals checked out of the library, assume you have the following items for this question: Item 1 due May 13, 2003: Item 2 due January 31, 2003: Item 3 due March 11, 2003: 5. [Exercise 4.3] Write Java specifications for commands that will change an Explorer's strength and stamina. You can find the specification for the class Explorer on page 81. 6. [3 points] Suppose you are designing an online ticket agent that sells tickets for concerts. A class, called TicketTracker defines objects that keep track of how many tickets have been purchased, how many tickets are left, and how much money has been spent on tickets. Each object (instance) of class TicketTracker represents information about the tickets sold for a particular concert. The TicketTracker class has the following properties and responsibilities: properties responsibilities Write the Java specifications for the class TicketTracker. Remember: the specifications include the constructors, the queries, and the commands, but not the private implementation details of the class. 7. [3 points] Implement the TicketTracker class by adding implementation details to the class specification from question 6. Use the upper window in DrJava to enter the code for the class. You can test your code by creating objects (instances) of the class in the lower interactions window. Use appropriate comments help the reader understand your code. Turn in your code by pasting it into your homework file. 8. Provide evidence that your TicketTracker class works properly. Give examples of code you used to test your class, followed by explanations of what happens when the code is executed. Provide evidence that the state of the object is what you expect. Also provide evidence that you tested multiple instances of the class TicketTracker.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
