How to calculate the area of a circle

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This example shows how to calculate the area of a circle.
First we ask the user for the radius of the circle.
The input is parsed to an integer value and finally we calculate the cirle area using the correct formula.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
*
* @author javadb.com
*/
public class Main {

    /**
     * Calculates the area of a circle
     */
    public static void main(String[] args) {

        int radius = 0;
        System.out.println("Please enter the radius of a circle");

        BufferedReader reader = null;
        try {
            //get the radius from user input
            reader = new BufferedReader(new InputStreamReader(System.in));
            radius = Integer.parseInt(reader.readLine());

        } catch (NumberFormatException nfe) {
            nfe.printStackTrace();
            System.exit(0);
        } catch (IOException ioe) {
            ioe.printStackTrace();
            System.exit(0);
        } finally {
            try {
                reader.close();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
        }

        double area = Math.PI * radius * radius;

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

    }
}

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