Question

In java 

Given the following UML class diagram, implement the class as described by the model. Use your best judgement when implementing the code inside of each method.

+------------------------------+
| Circle |
+------------------------------+
| - radius : double = 1.0 |
+------------------------------+
| + Circle(radius : double) |
| + getRadius() : double |
| + setRadius(radius : double) |
| + area() : double |
| + perimeter() : double |
+------------------------------+

The following information might also be useful:

Formula for area of a circle with radius r:
       A = πr^2

Formula for perimeter of a circle with radius r:
       P = π2r

Answer 1

Below is the JAVA code I hope that i have provided sufficient comments for your better understanding Note that I have done proper indentation but this code is automatically left alligned on this interface

import java.util.Scanner;
class Circle
{
   private double radius;
   static final double PI =3.14;   //constant
    public Circle()    //default constructor
    {
        radius = 1;
    }
   public Circle (double rad) //parameterized constructor
   {
       radius = rad;
   }
   public double getRadius()
   {
       return radius;
   }
   public void setRadius(double r)
   {
       radius = r;
   }
   double area()
   {
       return PI*radius*radius;
   }
   double perimeter()
   {
       return 2*PI*radius;
   }

   public static void main(String [] args)
   {
       Scanner input = new Scanner(System.in);
       Circle c1 = new Circle(); //default constructor invoked
       System.out.println("Enter the radius :");
       double r = input.nextDouble();
       c1.setRadius(r);
       System.out.println("Area of circle is :" + c1.area());
       System.out.println("Perimeter of circle is :" + c1.perimeter());
   }
}

Below is the screenshot of output