Objective: Exercise inheritance in Java. Java program: 1. Create a class named R

Question

Objective:
Exercise inheritance in Java.

Java program:

1. Create a class named Rectangle that has instance variables height and width. Provide a constructor that initializes the instance variables based on parameter values, getter and setter methods for the instance variables, a toString method, and a method named computeSurfaceArea(), that returns the surface area of

the rectangle.
2. Create a child class named RectPrism that contains an additional instance variable named depth. Provide a constructor, getter and setter methods for the new instance variable, and a method named computeVolume(), that returns the volume of the rectangular prism. Override the toString() and the computeSurfaceArea() methods.

3. Write an application called Demo, that instantiates a rectangle and a rectangular prism, and tests all the methods.

Explanation / Answer

Rectangle.java

public class Rectangle {
   double width;
   double height;
   public Rectangle(double width, double height) {
       super();
       this.width = width;
       this.height = height;
   }
   public double getWidth() {
       return width;
   }
   public void setWidth(double width) {
       this.width = width;
   }
   public double getHeight() {
       return height;
   }
   public void setHeight(double height) {
       this.height = height;
   }
   @Override
   public String toString() {
       return "Rectangle [width=" + width + ", height=" + height + "]";
   }
   public double computeSurfaceArea(){
       return this.width*this.height;
   }
}

RectPrism.java

public class RectPrism extends Rectangle{
   double depth;

   public RectPrism(double width, double height, double depth) {
       super(width, height);
       this.depth = depth;
   }

   public double getDepth() {
       return depth;
   }

   public void setDepth(double depth) {
       this.depth = depth;
   }
   public double computeVolume(){
       return this.width*this.height*this.depth;
   }

   @Override
   public String toString() {
       return "RectPrism [depth=" + depth + ", width=" + width + ", height=" + height + "]";
   }

   public double computeSurfaceArea(){
       return 2*(this.width*this.height+this.height*this.depth+this.depth*this.width);
   }
  
}

Demo.java:

public class Demo {

   public static void main(String[] args) {
       // TODO Auto-generated method stub
       Rectangle rectangle=new Rectangle(12, 15);
       System.out.println("Rectangle");
       System.out.println("Width:"+rectangle.getWidth());
       System.out.println("Height:"+rectangle.getHeight());
       System.out.println("Surface Area:"+rectangle.computeSurfaceArea());
       System.out.println();
       RectPrism prism=new RectPrism(12, 36, 14);
       System.out.println("RectPrism:");
       System.out.println("Width:"+prism.getWidth());
       System.out.println("Height:"+prism.getHeight());
       System.out.println("Depth:"+prism.getDepth());
       System.out.println("Volume:"+prism.computeVolume());
       System.out.println("Surface Area:"+prism.computeSurfaceArea());
      
   }

}

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