Write compile and test a program named ShapesDemo. The program will create sever

Question

Write compile and test a program named ShapesDemo. The program will create several objects that descend from an abstract class called GeometricFigure and demonstrate their methods as described below.

1. Each GeometricFigure includes: a height, a width, and an area.

2. Provide get and set accessors for each of the above fields except area; the area is computed and is read-only.

3. Include an abstract method called ComputeArea() that computes the area of the GeometricFigure.

4. Create three additional classes:

a. A Rectangle is a GeometricFigure whose area is determined by multiplying width by height.

b. A Square is a Rectangle in which the width and height are the same. Provide a constructor that accepts both height and width, forcing them to be equal if they are not1. Provide a second constructor that accepts just one dimension and uses it for both height and width. The Square class uses the Rectangle’s ComputeArea() method.

c. A Triangle is a GeometricFigure whose area is determined by multiplying the width by half the height. In the ShapesDemo class, after each object is created, pass it to a method that accepts a GeometricFigure argument in which the figure’s data is displayed. Change some dimensions of some of the figures and pass each to the display method again.

Explanation / Answer

GeometricFigure.java

public abstract class GeometricFigure {
   private double height;
   private double weight;
   private double area;
   public GeometricFigure(double height, double weight){
       this.height = height;
       this.weight = weight;
   }
   public double getHeight() {
       return height;
   }
   public void setHeight(double height) {
       this.height = height;
   }
   public double getWeight() {
       return weight;
   }
   public void setWeight(double weight) {
       this.weight = weight;
   }
   public abstract double ComputeArea();
}

Rectangle.java

public class Rectangle extends GeometricFigure {
   public Rectangle(double height, double weight){
       super(height, weight);
   }  
   public double ComputeArea(){
       return getHeight() * getWeight();
   }
}

Square.java

public class Square extends Rectangle{
   public Square(double height, double wieght){
       super(height, height);
   }
   public Square(double height){
       super(height, height);
   }
}

Triangle.java

public class Triangle extends GeometricFigure{
   public Triangle(double height, double weight){
       super(height, weight);
   }  
   public double ComputeArea(){
       return (0.5) * getHeight() * getWeight();
   }
}

ShapesDemo.java

public class ShapesDemo {

   /**
   * @param args
   */
   public static void main(String[] args) {
       // TODO Auto-generated method stub
       Rectangle2 r = new Rectangle2(2.4, 3.3);
       System.out.println("----------Rectangle Area------------");
       System.out.println(r.ComputeArea());
       Square s = new Square(2.4, 3.3);
       System.out.println("----------Square Area------------");
       System.out.println(s.ComputeArea());      
       Triangle t = new Triangle(2.4, 3.3);
       System.out.println("----------Triangle Area------------");
       System.out.println(t.ComputeArea());      
   }

}

Output

----------Rectangle Area------------
7.919999999999999
----------Square Area------------
5.76
----------Triangle Area------------
3.9599999999999995

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