Homework 2 - Review - Designing Classes

CS 2102 - Bterm 09

Homework 2 - Designing Classes with the Design Recipe

Due: Thursday, November 5 at 5pm

Acknowledgement: This assignment is a modified version of an assignment designed by Dr. Viera Proulx.

This assignment and all subsequent assignments are to be done with your homework partner.

Assignment Goals

To use the design recipe to design class hierarchies in ProfessorJ
To use the design recipe to design methods in ProfessorJ
To obtain some experience using the ProfessorJ libraries for drawing

Organizing your homework solutions

Please consider that you are writing up solutions for other people to read. Organize your work as follows:

Define your classes in the order in which the homework assignment asks for them. Clearly label with a comment the problem number to which the class definitions belong. For example, for Problem 1 in this assignment your file should be organized like this:
```
// PROBLEM 1

(class definition for City goes here)

(class definition for Location goes here)

(class hierarchy for list of cities goes here)

(class hierarchy for list of strings goes here)
```

Your Examples class should be the last class in your file. Organize your examples in order in which the homework assignment asks for them, and clearly label each set of examples with a comment; for example:

class Examples{

  Examples(){
  }

  // PROBLEM 1 - EXAMPLES OF DATA
  // Examples of Locations

  // Examples of Cities

  // Examples of lists of cities

  // Examples of lists of strings

  // PROBLEM 2 - EXAMPLES OF DATA
  // Examples of Cartesian Points

  // Examples of Shapes

  // PROBLEM 3 - TESTING METHODS
  // test toPosn

  // test distanceTo

  // test contains

  // test draw
}

The TAs have to look at a lot of programs. You probably want the TA to be happy when he or she is grading your solution - do whatever you can to make it easy to follow your program.

Problems

Using the Design Recipe for Data Definitions*, convert the data definitions for cities from Homework 1 to data definitions in the Beginner ProfessorJ language. Your class should be named City. You should have a separate class definition for Location to represent the locality's longitude and latitude. Make examples of data in an Examples class.
Define a class hierarchy to represent a list of cities. Make examples of data.
Define a class hierarchy that represents a list of strings (this data definition could be used to represent a list of states, where each state is identified by a two-letter string). Make examples of data.
*Design Recipe for Data Definitions
- Start with a class diagram (you don't have to pass it in, but you should make one, anyway)
- Document each class with a comment explaining the information represented by the data
- Provide examples of data
Design a class hierarchy to represent shapes that may be drawn on a Canvas. Here are the shapes you should define:
- A circle has the position of the center, the radius, and a color.
- A disk has the position of the center, the radius, and a color.
- A rectangle has the position of the NW corner, the height and the width, and a color.
- A line has the position of the start and end points and a color.
- A combo consists of two shapes, the top and the bottom.
Draw a class diagram of a class hierarchy that represent shapes. You won't be submitting it, but you should always start by drawing a class diagram. If you come for office hour help, we will ask you to show us your diagram.
Define a class CartPt to represent a Cartesian point with integer coordinates.
Define the classes that represent shapes. Use the CartPt class to represent the positions of shapes. Use the IColor class to represent the colors of the shapes. Use the Helpdesk in DrScheme to learn how to access the ProfessorJ colors library (Teachpacks/HtDC Teachpacks).
Make examples of data.
In this part of the homework you will use the Design Recipe for Methods* to design methods for your Shape classes. Make sure you provide test cases in the Examples class as you develop each method.
Design the method toPosn that produces an instance of the class Posn from this CartPt. The Posn class is defined in the ProfessorJ geometry library (look in the Helpdesk for information about the geometry library).
Design the method distanceTo() that computes the distance (a double) from this CartPt to the given CartPt.
Design the method contains() that determines whether this shape contains the given CartPt. (Note: To do this correctly for the class Line requires a bit of geometrical computation. You are allowed to substitute, in this case, a method that produces false for all inputs.)
Design the method draw() that draws this shape on the given Canvas (refer to the documentation in the draw library on Canvas). You can display shapes on a Canvas by providing statements such as the following in your Examples class:
```
  Canvas c = new Canvas(100, 100);

  boolean showShape = this.c.show() && this.myShape.draw(this.c);
```
where myShape is an example of a shape that has been defined in the Examples class.
*Design Recipe for Methods
- Formulate a purpose statement and a method header
- Illustrate the purpose statement with functional examples (test cases)
- Lay out what you know about the method's argument(s) (including this) in a template
- Define the method
- Run your test cases

What to Turn In

Using web-based turnin, turn in a single file containing all code and documentation for this assignment. Follow the naming conventions when naming your file. Both partners' names and wpi login names should appear in a comment at the top of the file.