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Why Abstracts Classes Are Useful

Implement all methods of the Rectangle, Circle and Triangle classes described below. Then download InteractiveMath and implement its methods

Class: Shape (superclass for all shape types)

instance Variables
  • private int color;
Accesor Methods
  • public double getArea(); What goes here?
  • public int getColor()

Class: abstract Polygon3 extends Shape

(superclass of Triangle3, Polygon3)
Constructor
  • public Polygon3(int sides) //this should use the paramater to initalize the instance varaible numSides
Instance Variables
  • private int numSides
Accesor Methods
  • no methods


Class: Triangle3 extends Polygon3


Constructor
  • Public Triangle3( ) //this should initalize the instance variables of Polygon as shown below;
      public Triangle3(double b,double height)
      	{
        super(3);
    	base =b;
    	height h
        }
      
instance Variables
  • double base
  • double height
Accesor Methods //override each of the superclass
  • public double getArea(); //returns the area of the triangle

Class: Circle extends Shape


Constructor
  • Public Circle(double r) //this should initalize the radius to the value of r;
instance Variables
  • private double radius;
Accesor Methods
  • public double getArea(); //returns the area of the circle

Insightful Few Lines of Code

Shape s = new Triangle3();
Class: InteractiveMath3
I already implemented computeNetArea()

instance Variables
  • ArrayList<Shape> shapes;
Accesor Methods
  • public double computeNetArea(){ //@ returns the area of the rectangles, circles and triangles
  • public void printColors()//loop over all objects, print each object's variables on a separate line .
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