Calculate the Area of Circle | Java Program

package com.swain.cell;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

public class CalculateCircleArea {

       public static void main(String[] args) {

              int radius = 0;

              System.out.println("Please enter radius of a circle");

              try {

                     // get the radius from console

                     BufferedReader br = new BufferedReader(new InputStreamReader(

                                  System.in));

                     radius = Integer.parseInt(br.readLine());

              }

              // if invalid value was entered

              catch (NumberFormatException ne) {

                     System.out.println("Invalid radius value" + ne);

                     System.exit(0);

              } catch (IOException ioe) {

                     System.out.println("IO Error :" + ioe);

                     System.exit(0);

              }

              /*

               * Area of a circle is pi * r * r where r is a radius of a circle.

               */

              // NOTE : use Math.PI constant to get value of pi

              double area = Math.PI * radius * radius;

              System.out.println("Area of a circle is " + area);

       }

}