Calculate the Area of Circle | Java Program

Following Program will show you how to calculate area of circle using it's radius

/*
        Calculate Circle Area
*/
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
 
public class CalculateCircleAreaExample {
 
        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);
        }
}
 
/*
Output of Calculate Circle Area using Java Example would be
Please enter radius of a circle
19
Area of a circle is 1134.1149479459152
*/