CIS 180: Object-Oriented Programming
Programming Project #2

An Invoice object maintains information about the purchase of some software and is capable of printing an invoice of a customer's purchases from the Acme Software Company. Design and implement an Invoice class. Here are some additional specifications:

• Instance Variables: The Invoice class should have instance variables to represent the customer's name, the name of the software that is being purchased, and the price of the software.
• Constructor Method: A constructor method should allow the customer's name to be set when an instance of this class is created.
• Instance Methods: The Invoice class should include mutator and access --set() and get()--methods for each of its instance variables.
• Output Method: The Invoice class should contain a print() method that prints a hard copy of the invoice. Note that different softwares have different prices. Here's two samples of printed invoices:

  -----------------------------------
  Acme Software Invoice
  Customer Name: Trinity College
  Software Title: Chess for Beginners
  Aount due: $199.00
  -----------------------------------

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Acme Software Invoice
Customer Name: UMass Dartmouth
Software Title: Checker for Experts
Aount due: $98.00
-----------------------------------

Problem Decomposition

This problem can be divided into one class, the Invoice class, which will contain the instance variables and methods described above. Include a main() method in the class so that you can create Invoice objects that can be used to test your set() and get() methods.

Design

• Step 1. Draw a UML class diagram of the Invoice class, showing all of the instance variables and methods, including their accessibility (public or private) and data types (String or double).
• Step 2. Develop a written specification for the Invoice class based on your UML diagram. This will become a comment block at the beginning of your source file.
• Step 3. Create a project named Homework2,  and saving the project on your desktop. 
• Step 4. Type the specification you developed in Step 2 into a Java comment block and save it in a file named Invoice.java. This file will be the file you use for defining the Invoice class. The comment will serve as documentation for the program.
  

Implementation (Stepwise Refinement)

• Code the initial comment block (purpose of your program, your name, lab section, etc) and the basic class definition.

• Code the declarations for the class's instance variables as well as the constructor method.

• Add code to the main method to create and use one Invoice object.

• Add code to the main method to create and use a second Invoice object.

What to turn in

When your assignment is complete, add some comments to the beginning of the java source code explaining any problems you encountered in completing the assignment and describing any bugs in your solution. Undocumented bugs are worse than documented bugs. If you have undocumented bugs we will assume that you did an inadequate job of testing your code, and you will lose additional points.

To submit your homework, follow the link from the homework page to the homework submission form.

There will be a 10% penalty for assignments received after the due date. Assignments will not be accepted more than one week past the due date.

You're done. Great work!