4. Write a Circle class that has the following variables: • radius: a double • p

Question

4. Write a Circle class that has the following variables: • radius: a double • pi: a double initialized with the value 3.1416 The class should have the following member functions: • Default constructor: a default constructor that sets radius to 0.0. • Constructor. Accepts the radius of the circle as an argument • setRadius. A mutator function for the radius variable • getRadius. An accessor function for the radius variable • getArea. Return the area of the circle, which is calculated as area = pi * radius * radius • getDiameter. Return the diameter of the circle, which is calculated as diameter = radius *2 • getCircumference. Return the circumference of the circle, which is calculated as circumference = 2 * pi * radius. Write a program the demonstrate the Circle class by asking the user for the circle's radius, creating a Circle object, and then reporting the circle's area, diameter, and circumference.

Explanation / Answer

Circle.java

package com.chegg.test;

/**
* This class is used to calculate the area,diameter&circumference of a circle
*
* @author Your Name
*
*/
public class Circle {
   double radius;
   double pi = 3.1416;

   /**
   * Default Constructor to initialize the radius with 0.0
   */
   Circle() {
       this.radius = 0.0;
   }

   /**
   * Parameterized constructor to create circle object
   *
   * @param radius
   */
   Circle(double radius) {
       setRadius(radius);
   }

   /**
   * @return the radius
   */
   public double getRadius() {
       return radius;
   }

   /**
   * @param radius
   * the radius to set
   */
   public void setRadius(double radius) {
       this.radius = radius;
   }

   /**
   * Method to return the area of a circle
   *
   * @return area
   */
   public double getArea() {
       double tempRadius = getRadius();
       double area = pi * tempRadius * tempRadius;
       return area;
   }

   /**
   * Method to calculate the diameter of a circle
   *
   * @return diameter
   */
   public double getDiameter() {
       double tempRadius = getRadius();
       double diameter = tempRadius * 2;
       return diameter;
   }

   /**
   * Method to calculate the circumference of a circle
   *
   * @return circumference
   */
   public double getCircumference() {
       double tempRadius = getRadius();
       double circumference = 2 * pi * tempRadius;
       return circumference;
   }

}

CircleTest.java

package com.chegg.test;

import java.util.InputMismatchException;
import java.util.Scanner;

public class CircleTest {
   public static void main(String[] args) {
       Scanner sc = new Scanner(System.in);
       System.out.println("Enter the radius of the circle");
       // Reading input radius from the user
       double rad = 0.0;
       try {
           rad = sc.nextDouble();
       } catch (InputMismatchException ime) {
           System.out.println("Enter the radius in numeric format only");
           System.exit(0);
       }
       // Creating the object of a circle
       Circle circle = new Circle(rad);
       // Getting the area of a circle
       System.out.println("The area of the circle:" + circle.getArea());
       // Getting the diameter of a circle
       System.out
               .println("The diameter of the circle:" + circle.getDiameter());
       // Getting the circumference of a circle
       System.out.println("The circumference of the circle:"
               + circle.getCircumference());
       // Closing the scanner.
       sc.close();
   }
}

Output:

Enter the radius of the circle
3
The area of the circle:28.2744
The diameter of the circle:6.0
The circumference of the circle:18.8496

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