A02

Due Date: Thursday, January 25
File(s) to be submitted: Person.java, Student.java, Undergrad.java, Graduate.java, Employee.java, Faculty.java, Staff.java, Payable.java
Sample Output: SampleOutput.html
Starter Files:

• Person.java
• Student.java
• Undergrad.java
• Graduate.java
• OurSchool.java

Interfaces & Inheritance

Summary

For this assignment you are to extend the Person-Student-Undergraduate inheritance hierarchy discussed in class. In particular, you are to create the classes and interface shown in this diagram:

The four classes on the left of the diagram (Person, Student, Undergraduate, and Graduate) have already been provided.

Give each of Student, Undergraduate and Graduate a writeOutput method (as described below).

Also, revise Person so that it sorts naturally by name, and give Employee a Comparator that allows Employees to be sorted by income, from highest to lowest.

I have provided a sample program you can use to test your code. Parts of the program are commented out. You will need to activate those parts of the program as you complete each part of the assignment.

Details

Here are the descriptions of each class.

• Employee An Employee is a person employed by the university. Each Employee has an employee number (an int value) which is generated automatically, starting at 10000.

  This class is abstract. It implements (abstractly) the Payable interface (described below).

  I didn't discuss abstract classes in lecture, but they are somewhere between classes and interfaces. Some of their methods have definitions, and some do not.

  • The methods that do not have a definition must have the word abstract added to their header, just before the return type. For example:
    public abstract void noDefinition(String arg);
  • The class itself must also have the word abstract in its header, just before the word class:
    public abstract class NotAllDefined

• Faculty A Faculty member is an Employee who teaches courses at the university. Each faculty member has an annual salary (a double value -- how much they are paid each year -- which must be at least $1.00).
• Staff A Staff member is someone who works for the university in anything other than a teaching role. Each Staff member has an hourly wage (a double value -- how much they are paid per hour -- which must be greater than (or equal to) the minimum wage).
• Payable This is an interface. To implement this interface, a class must implement the following methods:
  • String getName() Returns the name of the Employee (can't write someone a cheque if we don't know their name);
  • double payForWeek() Returns the amount of money paid in a typical week (40 hours for a Staff member, or 1/52 of an annual salary);
  • double payForYear() Returns the amount of money paid in a typical year (an annual salary, or 52 weeks for someone paid hourly).

For each class you are to implement the following methods (which are the same methods you find in the classes already implemented):

• A constructor, which is given all the required information to initialize all the fields for an object the class, and does so. If a requested value is inappropriate, the method should throw an exception.
• A getter for each instance variable of this class. (In this case there will be only one instance variable in each class.)
• A setter for each non-final instance variable of this class. (In this case there will be at most one non-final instance variable in each class.) It is responsible for making sure that any restrictions on the value of the variable are applied. If a value is inappropriate, the method should throw an exception.
• void writeOutput(), which writes out the information for the object (name, number, previous degree, salary, wage, ...) making use, where possible, of the super-type's writeOutput method.

The Faculty and Staff classes will, of course, also have to implement the methods given in the Payable interface.

The Employee class should define appropriate constants for the number of weeks in a year, the number of hours in a week, and the minimum wage (which I hear is $11.55 per hour). The Faculty and Staff classes should use them.

Hints

The classes you create will all be very similar to the Student and Undergraduate classes supplied to you.

The Faculty and Staff classes do not need to say that they implement Payable, even tho they do. Because they are sub-classes of Employee, the computer will know.

Test your inheritance hierarchy using the OurSchool program I have provided for you. You may want to examine it before you begin the assignment -- it has some method names that you must use.