CS 220X, D-term 2015

Homework 4

Due: Tuesday, April 14 Thursday, April 16 at 5pm

Outcomes

After successfully completing this assignment, you will be able to...

design a Java program that uses multiple classes, given the program requirements
~~develop classes that follow the principles of encapsulation~~
use Exceptions to handle unusual or error conditions

Before Starting

Review Chapters 7 - 11 in Horstmann.

The Assignment

For Homework 4 you'll build an application that manages students and courses in a registrar's database. At the heart of every program is the logic, or functionality, that the program implements. This is often referred to as the business logic, or the model. For this project, you will design and implement the business logic of your registrar program, as well as a simple command line application that demonstrates the program's capabilities. (In a follow-up assignment, we'll extend this project to provide a user interface that will take the place of the command line application.)

Requirements

Your registrar program must

Maintain the following information for each student:
- student id (the key for uniquely identifying a student)
- last name
- first name
- list of courses the student is currently enrolled in
- list of completed courses (and the grade earned for each one)
Of course, in a real student database other information would be kept for each student, such as major, year of graduation, GPA, home address, etc. We're intentionally keeping this program "bare bones" so that you learn the basics of designing a program from specifications. Additional fields and methods could always be added later.
Maintain the following information for each course:
- department that offers the course (like "CS")
- course number (like "220X")
- course title
The key for uniquely identifying a course is the combination of department and course number.
Maintain a list of students.
- A student can be added to the list
- A student can be deleted from the list. The student to be deleted should be identified by the student id.
- The grade in a course can be changed for a student in the list. The student would be identified by student id. The course would be identified by its department and course number.
- The current courses that have been assigned grades can be "rolled" into the list of the student's completed courses.
Using the last two operations (changeGrade and roll) is similar in spirit to what I do in BannerWeb at the end of the term. BannerWeb maintains a list of all students enrolled in CS 220X. I change the grade of each student enrolled in CS 220X from its original (non-credit) value to the student's earned grade in the course. Then I submit the changed grades, which updates the grade information in the Registrar's database. In BannerWeb I work with a list of courses that contain information about students. In this assignment, we're working with a list of students that contain information about courses. But the basic ideas are the same.
I suggest you use something like "IP" for the grade of a current course, where "IP" means "in progress". The "roll" (or submit) method should move all courses in the current course list which have non-IP grades into the list of completed courses. Of course, in true WPI fashion, if the earned grade in a course is "NR", it should be removed from the list of current courses, but not added to the list of completed courses.
Your program should define exceptions StudentAlreadyExists, StudentNotFound, and CourseNotFound. These exceptions should be thrown where appropriate (e.g. if you try to delete a student from the list of students, and the list contains no such student with the given ID, the StudentNotFound exception should be thrown).
Provide a main method that demonstrates the capabilities of your program. Each class should provide a toString() method so that the main method can display the results of each operation. You're encouraged to develop a set of JUnit tests to incrementally test each method as you write it. We won't be grading your JUnit tests (but that doesn't mean you shouldn't develop them!)

(IGNORE THIS SECTION - WE'LL TALK MORE ABOUT ENCAPSULATION IN A WEEK OR TWO) Pay particular attention to encapsulation. As we've discussed, proper choice of public/private modifiers is one aspect of encapsulation. Another aspect concerns defining methods in the proper place. Remember our rule of thumb: don't ask for the information to do the work, ask the class that has the information to do the work for you.

Deliverables

Export your Eclipse project to a zip file and submit the zip file via web-based turnin. To export a project, go to File | Export… and choose Archive File from the General folder. Check off the entire project in the top left window and make sure the format is .zip and not .tar. Finally, give the archive file a name and click finish.

The name of the turnin project is Homework 4.

Programs submitted after 5pm on April 14 will be tagged as late, and will be subject to the late homework policy.

Grading

Your program must compile without errors in order to receive any credit. It is suggested that before you submit your program, you should compile it one more time to make sure that it compiles correctly.