Calculate Circle Area using Java - Java Language Basics

Java examples for Language Basics:int

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Introduction

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

use Math.PI constant to get value of pi

Demo Code

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

public class Main {

  public static void main(String[] args) {
    int radius = 0;
    System.out.println("Please enter radius of a circle");

    try {/*w  ww  .ja v a  2  s  . co m*/
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      radius = Integer.parseInt(br.readLine());
    }
    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);
    }

    double area = Math.PI * radius * radius;

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

Result


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