Question

Program 7 - Circle You write ALL the code, then run it - Produce the correct output. Turn in code and screen print of successful run, for credit * Write a class for a Circle * Input only the radius. * Write functions that Calculate the circles Circumference, Area and Diameter, and print out the value of the radius * Include error checking for radius, must be greater than zero. Test all combinations

Answer 1

Answer:

Here is the Circle class:

public class Circle {   // class definition

private int radius;    // private data member of type int of class Circle named radius that stores the value of radius

public Circle(int r) {   // parameterized constructor of class Circle that takes radius as argument

 radius = r;  }    // sets value of radius as r

public int getRadius() {   // accessor method to get the value of radius

 return radius;  }   // returns the current value of radius

public int Diameter() {   // method to compute diameter of a circle

 return radius * 2;  }   // multiply radius value by 2 to compute diameter of Circle

 

public double Area() {   // method to compute area of a circle

 return Math.PI  * Math.pow(radius, 2);   }   //the formula of area is

π x radius² where value of π is get using Math.PI

 

 public double Circumference() {   // // method to compute circumference of a circle

 return 2* Math.PI * radius;   }   }  //the formula of circumference is

2 x π x radius where value of π is get using Math.PI

Explanation:

Here is the Main class:

import java.util.Scanner;  //to accept input from user

public class Main {  //definition of Main class

public static void main(String[] args) {  //start of main method

   

    Scanner scanner = new Scanner (System.in);  //creates Scanner object to take input from user

    System.out.println("Enter radius: ");  //prompts user to enter radius

    int r = scanner.nextInt();  //reads the value of radius from user

 Circle c = new Circle(r);  // calls Constructor of Circle passing r as argument to it using the object c of class Circle

 

    if(c.getRadius()<=0){  //calls getRadius method to get current value of radius using objec and checks if this value (input value of r ) is less than or equal to 0

        System.out.println("Error!");   }  //when above if condition evaluates to true then print this Error! message

    else {  //if the value of radius is greater than 0

System.out.println("the radius of this Circle is: " +c.getRadius());  //calls getRadius method to return current value of r (input value by user)

System.out.println("the diameter of this Circle  is: " + c.Diameter());  //calls Diameter method to compute the diameter of Circle and display the result on output screen

System.out.printf("the circumference of this Circle  is: %.2f", c.Circumference());  //calls Circumference method to compute the Circumference of Circle and display the result on output screen

System.out.println();  //prints a line

System.out.printf("the Area of this Circle  is: %.2f", c.Area()); } }  }

//calls Area method to compute the Area of Circle and display the result on output screen

The program and its output is attached.