Lab 4, CSC/CPE 203 – Interfaces

Lab 4, CSC/CPE 203 – Interfaces

Orientation
For this lab you will create a virtual drawing workspace on which you can place various geometric
shapes. You will not actually be drawing the shapes in this program rather; you will simply be
representing geometric shapes as objects and providing the ability to place them in space. The
workspace will make use of a List from the Java Standard Library to collect shapes and will have
methods that allow you to add, remove, and inspect the shapes it contains. All of the shapes share a
common set of methods defined by a Java interface. The behavior of these common methods varies, as
appropriate, by shape. In addition, each shape has one or more methods unique to it. The following
shapes will be supported: circle, rectangle, triangle, and convex polygon.
Objectives
• To develop and demonstrate basic object-oriented development skills. Much of the structure of
the solution is given - use good judgment when "filling in the blanks".
• To become familiar with Java interfaces and the concept of polymorphism.
• To practice using the instanceof operator.
• More practice using existing classes and interfaces from the Java Standard Library, such as:
List, ArrayList, LinkedList, Point, and Color.
Given File
Retrieve the file provided for this lab from Canvas.
The given file is a starter junit test file for your code. Be sure to add to this file to make sure your code is
working properly. Your instructors have a much more extensive test file that they reserve the right to test
your implementation with!
Ground Rules
Many of the classes and interfaces you will be writing in this lab have counterparts in the Java Standard
Library. You may not use the Java Standard Library versions in your implementation unless explicitly
instructed to do so (see below). The Java Standard Library classes and interfaces you may use are
identified by a complete package specification. For example, you will be using the java.awt.Color,
java.awt.Point, and java.util.List classes/interfaces from the Java Standard Library. You may
also use the java.lang.Math class from the Java Standard Library (even though it is not explicitly
referenced in this document). Any classes or interfaces in the specifications below (other than Point,
Color, and List) must be entirely written by you. If you have any questions regarding this restriction please
be sure to ask your instructor early in the development process (ideally, before you have written any
code!).
As stated above, your classes and interfaces will use many classes that already exist in the Java
Standard Library. For example, to use the Color and Point classes, you will need to import
java.awt.Color and java.awt.Point.
Some of your code from Lab 2 can be reused but will need to be re-written to match this specification.
Task
You must define the Shape interface and implement the Circle, Rectangle, ConvexPolygon,
Triangle, and Workspace classes as described below. The specific instance variables are not explicitly
specified. Remember, each instance variable makes every object of the class require more memory. All
instance variables should be essential to defining the state of an object and/or provide a significant
computational efficiency or reduction in code complexity. Other variables should be declared as local
variables in the method where they are used. Be ready to justify your choices! Be sure all your instance
variables maintain encapsulation (i.e. are private).
Also, you may add helper methods other than the methods specified below, but the additional methods
must be private.
1. Define a Java interface Shape with the following methods. (Note that the input parameters for
each method, if any, are intentionally not shown. You must figure out what is needed):
o Color getColor() - Returns the java.awt.Color of the Shape.
o void setColor() - Sets the java.awt.Color of the Shape.
o double getArea() - Returns the area of the Shape
o double getPerimeter() - Returns the perimeter of the Shape
o void translate() - Translates the entire shape by (add) the (x,y) coordinates of a
given java.awt.Point.
2. Define a Java class Circle that implements the Shape interface. Circles have a radius, a
center, and a Color. In addition to implementing the required methods specified by the Shape
interface, you must also implement the following methods. (Again, note that the input parameters
for each method, if any, are intentionally not shown):
o Circle() - A constructor with parameters to initialize all its instance variables. Do not
implement a default constructor.
o double getRadius() - Returns the radius of the Circle.
o void setRadius() - Sets the radius of the Circle
o Point getCenter() - Returns the center of the Circle
Note: Be sure to use the constant Math.PI when performing any calculations involving PI.
3. Define a Java class Rectangle that implements the Shape interface. Rectangles have a width,
a height, a Point indicating the topLeftCorner, and a Color. In addition to implementing the
required methods specified by the Shape interface, you must also implement the following
methods. (Again, note that the input parameters for each method, if any, are intentionally not
shown):
o Rectangle() - A constructor with parameters to initialize all its instance variables. Do
not implement a default constructor.
o double getWidth() - Returns the width of the Rectangle.
o void setWidth() - Sets the width of the Rectangle
o double getHeight() - Returns the height of the Rectangle.
o void setHeight() - Sets the height of the Rectangle
o Point getTopLeft() - Returns the Point representing the top left corner of the
Rectangle
4. Define a Java class Triangle that implements the Shape interface. Triangles have three Points
indicating its vertices and a Color. To simplify your solution, the vertices will always be given in
counter-clockwise order. However, there are calculations for the area of a Triangle that will work
with the vertices in any order. In addition to implementing the required methods specified by the
Shape interface, you must also implement the following methods. (Again, note that the input
parameters for each method, if any, are intentionally not shown):
o Triangle() - A constructor with parameters to initialize all its instance variables. Do not
implement a default constructor. The first Point passed to the constructor will be vertex
A, the second Point vertex B, and so on.
o Point getVertexA() - Returns the Point representing vertex A of the Triangle.
o Point getVertexB() - Returns the Point representing vertex B of the Triangle.
o Point getVertexC() - Returns the Point representing vertex C of the Triangle.
5. Define a Java class ConvexPolygon that implements the Shape interface. A ConvexPolygon
have a java Point array (not ArrayList) indicating its vertices and a Color. Assume the
Points in the Point array will always be given in counter-clockwise order. In addition to
implementing the required methods specified by the Shape interface, you must also implement
the following methods. (Again, note that the input parameters for each method, if any, are
intentionally not shown):
o ConvexPolygon() - A constructor with parameters to initialize all its instance variables.
Do not implement a default constructor.
o Point getVertex() - Takes an index and returns the specified vertex of the
ConvexPolygon.
6. Define a Java class WorkSpace to hold Shape objects. The WorkSpace class should have one
private instance variable of type List<Shape> to hold Shape objects. You may choose which
kind of List you use. The WorkSpace class should have the following public methods. (Note
that this time the parameters are specified!):
o WorkSpace() - A default constructor to initialize its instance variable to an empty List.
The constructor should not take any parameters. (If you do nothing in this constructor,
you may omit it from your code altogether.)
o void add(Shape shape) - Adds an object which implements the Shape interface to
the end of the List in the WorkSpace.
o Shape get(int index) - Returns the specified Shape from the WorkSpace.
o int size() - Returns the number of Shapes contained by the WorkSpace.
o List<Circle> getCircles() - Returns a List of all the Circle objects contained
by the WorkSpace.
o List<Rectangle> getRectangles() - Returns a List of all the Rectangle
objects contained by the WorkSpace.
o List<Triangle> getTriangles() - Returns a List of all the Triangle objects
contained by the WorkSpace.
o List<ConvexPolygon> getConvexPolygons() - Returns a List of all the
ConvexPolygon objects contained by the WorkSpace.
o List<Shape> getShapesByColor(Color color) - Returns a List of all the
Shape objects contained by the WorkSpace that match the specified Color.
o double getAreaOfAllShapes() - Returns the sum of the areas of all the Shapes
contained by the WorkSpace.
o double getPerimeterOfAllShapes() - Returns the sum of the perimeters of all the
Shapes contained by the WorkSpace.
Remember to use the instanceof operator in the appropriate places of your solution.
Suggestions
Note that these are merely suggestions. You are not required to follow them.
• Write the Shape interface first.
• After creating the Shape interface, write one class at a time that implements the interface. Test
and debug until you are satisfied with its design, implementation, and functionality. Then move on
to the next class.
• Implement the WorkSpace class last, and develop it incrementally, testing as you go. Notice that
many of the methods are similar and differ only by the Shape type that they work with.
• The given TestCases test the implementation specifics of each of your classes. Comment out
the classes that you have not yet implemented so that you can develop and test incrementally.
• Mathwords is a good reference!
Testing
You are given a starting test file to help you write your tests. It includes some tests for Circle, WorkSpace,
and your implementation specifics. This file is a good place to find some of the expected method
parameters if you are stuck. You are expected to add to this test file to thoroughly test all of your code!
Submission
All your .java files must be submitted as a one ZIP file, to the Canvas before deadline. Demo your work
when you finished the Lab.
Rubric
1) Part one Implementation: Points
a. Interface 5
b. Circle 5
c. Triangle 5
d. Poly 5
e. Rectangle 5
f. Workspace 5
g. Test Cases 10
2) ExtraTest Cases 30 (Test all your classes and methods)
3) Submission 30