Homework 3
CS202, Summer 2004

Due: Thursday, July 15

Please email your solutions to csun@calstatela.edu, and make sure to use CS202 Summer 04 HW3 as the subject of the email. The email should include your name, and the .java files for all the exercises as attachments. For all homework assignments and projects, failing to comply with the required code conventions (see Review of Language Basics, slide #7) will incur a credit penalty up to 10% of the total credit for the assignment.

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1. Read the following sections of SUN's Java Tutorial

• Object-Orient Programing Concepts
  
• What Is an Object?
• What Is a Message?
• What Is a Class?
• What Is Inheritance?
• Classes and Inheritance
• Creating Classes
• Managing Inheritance (up to Writing Abstract Classes and Methods)
  

2.(60pt) [Stanford]  For this problem, you will design and implement Java classes suitable for storing information about university instructors. There are three types of instructor: Professor, Lecturer, and Grad student. At any time, an instructor can best be described by three quantities: number of unread e-mail messages, age, and number of eccentricities. An instructor should respond to an init message which sets their age and sets them to have no unread mail and no eccentricities.

There are two measures of an instructor's current mood: stress and respect. An instructor's stress level is the number of unread messages.
However, stress is never more than 1000. Grad students are the exception. Their stress is double the number of unread messages and their maximum stress is 2000. Generally, an instructor's level of respect in the community is their age minus the number of eccentricities. Respect can never be negative. Professors are the exception: a Professor's eccentricities are regarded as "signs of a troubled genius" thereby increasing respect. So for Professors respect is age plus number of eccentricities.

Everything in an instructor's life is driven by receiving e-mail. Several things happen when an instructor gets new, unread e-mail:

• First, the amount of unread mail is increased.
• Second, 90% of the time, there will be no change in the eccentricities. 10% of the time, the number of eccentricities will randomly go up or down by one.
• Third, the new unread mail may cause the instructor's stress factor to become larger than their respect factor which makes the instructor unhappy. In this case, instructors have different coping mechanisms. Professors react by gaining 10 eccentricities. Lecturers react by accidentally deleting half their unread mail. Grad students react by reading all of their unread mail. The resulting mental anguish causes the Grad student's eccentricities to go up or down by one randomly. The coping mechanism may or may not bring the stress and respect factors back in line. The coping mechanism is activated at most one time for each batch of incoming mail.

To receive full credit for this exercise, you must take advantage of inheritance to maximize code re-use, and it goes without saying that you need some testing code, e.g. InstructorTest.java, to make sure your classes and methods work properly.