Question

Write a code in Java where:

Create two subclasses for the geometric objects: a circle, and a rectangle.

They must invoke the displayGeometricObject method to display the objects.

The displayGeometricObject displays the area and diameter if the object is a circle, and displays area if the object is a rectangle.

Answer 1

public abstract class GeometricObject {

   private String color = "white";

   private boolean filled;

   private java.util.Date dateCreated;

   /** Construct a default geometric object */

   protected GeometricObject() {

       dateCreated = new java.util.Date();

   }

   /** Return color */

   public String getColor() {

       return color;

   }

   /** Set a new color */

   public void setColor(String color) {

       this.color = color;

   }

   /** Return filled. Since filled is boolean,

so, the get method name is isFilled */

   public boolean isFilled() {

       return filled;

   }

   /** Set a new filled */

   public void setFilled(boolean filled) {

       this.filled = filled;

   }

   /** Get dateCreated */

   public java.util.Date getDateCreated() {

       return dateCreated;

   }

   /** Return a string representation of this object */

   public String toString() {

       return "created on " + dateCreated + "\ncolor: " + color +

               " and filled: " + filled;

   }

   /** Abstract method getArea */

   public abstract double getArea();

   /** Abstract method getPerimeter */

   public abstract double getPerimeter();

}

############

public class Circle extends GeometricObject {

   private double radius;

   public Circle() {

   }

   public Circle(double radius) {

       this.radius = radius;

   }

   /** Return radius */

   public double getRadius() {

       return radius;

   }

   /** Set a new radius */

   public void setRadius(double radius) {

       this.radius = radius;

   }

   /** Return area */

   public double getArea() {

       return radius * radius * Math.PI;

   }

   /** Return diameter */

   public double getDiameter() {

       return 2 * radius;

   }

   /** Return perimeter */

   public double getPerimeter() {

       return 2 * radius * Math.PI;

   }

  

   /* Print the circle info */

   public void printCircle() {

       System.out.println("The circle is created " + getDateCreated() +

               " and the radius is " + radius);

   }

}

###########

public class Rectangle extends GeometricObject {

   private double length, width;

   public Rectangle() {

   }

   public Rectangle(double length, double width) {

       this.length = length;

       this.width = width;

   }

  

   public double getLength() {

       return length;

   }

   public double getWidth() {

       return width;

   }

   public void setLength(double length) {

       this.length = length;

   }

   public void setWidth(double width) {

       this.width = width;

   }

   /** Return area */

   public double getArea() {

       return length*width;

      

   }

  

   /** Return perimeter */

   public double getPerimeter() {

       return 2 * (length+width);

   }

   /* Print the circle info */

   public void printRectangle() {

       System.out.println("The rectangle is created " + getDateCreated() +

               " and the length is " + length+", widht: "+width);

   }

}

############

public class TestGeometricObjects {

  

   static void displayGeometricObject(GeometricObject[] objs) {

      

       for(GeometricObject obj : objs) {

          

           if(obj instanceof Circle) {

               System.out.println("Diameter: "+((Circle)obj).getDiameter());

               System.out.println("Area: "+obj.getArea());

           }else{

               System.out.println("Area: "+obj.getArea());

           }

       }

   }

  

   public static void main(String[] args) {

      

       GeometricObject[] arr = {

           new Circle(4.5), new Rectangle(4, 5), new Circle(6)  

       };

      

       displayGeometricObject(arr);

      

   }

}

/*

Sample run:;

Diameter: 9.0

Area: 63.61725123519331

Area: 20.0

Diameter: 12.0

Area: 113.09733552923255

*/