How to do simple class Circle with one field radius. Supply one constructor that makes the radius of the circle as a parameter. Supply one method getArea ,that computes and returns (not prints)the area of a circle. Provide the accessor method getRadius. How to create a small class CircleTest with a main method that prompts the user to enter an integer value for the radius, creates one Circle object with that radius, calls it getArea method, and prints out the returned value.

import java.util.Scanner;

public class Circle {

   private double radius;

   //The constructor

   public Circle(){

   }

   //Method to compute and return the area

   public double getArea(double radius){

       double area = Math.PI *(radius*radius);

       return area;

   }

   //Accesor method (getRadius)

   public double getRadius() {

       return radius;

   }

}

class CircleTest{

   //The main method

   public static void main(String[] args) {

       //Scanner Class to receive user input

       Scanner in = new Scanner(System.in);

       System.out.println("Enter Radius");

       double r = in.nextDouble();

       //Make an instance of the class Circle

       Circle circle = new Circle();

       //Calculating the area

       double calArea = circle.getArea(r);

       //Printing out the area

       System.out.println("The area is: "+calArea);

   }

}

Explanation: