Project 8: Another calculator

The goal of this project is to put the state pattern to use.

1. Introduction

You will be writing one last calculator program for this class. This time we'll be back to a normal calculator. But this time you will be incorporating what we learned about the state pattern in your design of the calculator.

2. Setup

In this project you will use the same GUI and other starter code as the other calculator projects.

cp -r ~tvandrun/Public/cs245/proj2/* .

3. Calculator details

Now you'll be operating under the following rules:

• No using ifs, switches, exception handling, or degenerate loops. All decisions must be done using polymorphism, except when dealing with division by zero or screen formatting-- for those you may use either an if or exception handling.

  (What's a "degenerate loop"? Something like this:

  // I want to check is x < 3 but I can't use an if.
  // I'll use a while loop instead. I'm so clever...
  
  while (x < 3) {
      System.out.println("Now I know that x is less than three!!!");
      break;   // ok, break out of this "loop"
  }
  

  Generally, the point of all this is not to find sneaky ways to build the equivalent of ifs but to use polymorphism.)

• Follow the same specification for the operation of the calculator as from project 2 (see below).
• Use the state pattern to govern the behavior of the calculator.

4. Specification details

See the equivalent section from Project 2. All those things count here, too.

5. Reminder about setup()

(Largely repeated from project 5)

To clarify one part of the framework for this and other calculator projects, please note that when your submission is graded, your setUpCalculator() method will be called, and it will be given an object implementing the CalculatorFace interface you are given, but it will not be an instance of the ConcreteCalculatorFace class. ConcreteCalculatorFace is given for your own testing purposes. That is why your code should not be dependent on that class, only on the interface. Also, the main method of SetUp will not be called, only the setUpCalculator() method. In short, the contract you need to fulfill is

6. To turn in

Please turn in all the files you wrote or modified (ie, the files you didn't modify don't need to be turned in) to a turn-in directory. To turn in a specific file, do

cp (some file) /cslab.all/ubuntu/cs245/turnin/(your user id)/proj8

DUE: Wednesday, Apr 27, 5:00 pm. Note that if still have your two late days, then this makes Friday, Apr 29 (the last day of classes) the effective due date. Moreover, this project overlaps with project 9 (which will be a short project); project 9 will be due Apr 27, and no late days may be applied to project 9.

7. Grading

Grading for this project will follow this approximate point breakdown (the right to make minor adjustments in point distribution is reserved):

• Correctness: 15 (How does your calculator behave when tested against various button-sequence scenarios?)
• Use of state pattern and other design aspects: 5 (Does your code conform to the specific rules of this project, and how well does your code adhere to other principles of good design? How much improvement have you made since Project 2?)
• Documentation/coding style: 2 (How well does your code adhere to the documentation and style principles?)

Note both that this project is worth a little more in total than Project 2 (22 points vs 20 points) and that design and style is worth more proportionately.