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.
