Java Program to Calculate Area of Circle

Task: Java Program to Calculate Area of Circle

What is the formula for calculating Area of Circle?

The required formula for calculating area of circle is:

area = π . r²

Where r is the radius of the circle and π  is a mathematical constant with fixed value 3.1415.

Java program to input radius and find area of circle

We should declare a constant for pi in this Java program, it will enhance program readability and clarity. Here is a detailed explaination on How to Declare a Constant in Java Programs With Examples.

The source code of the Java program to input radius and find area of circle

/*
 Write a Java Program to input radius of a
circle and display the area of circle. Use the formula:
area = π . r2  where r is radius and π is a 
mathematical constant with constant value 3.1415
Use a named constant for π.
 */
package areaofcircle;
/**
 * @author EasyCodeBook.com
 */
import java.util.Scanner;
public class AreaOfCircle {
    public static void main(String[] args) {

        double radius, area;
        final double PI = 3.1415;
        Scanner input = new Scanner(System.in);
        System.out.print("Enter radius of circle=");
        radius = input.nextDouble();
        area = PI * radius *radius;
        System.out.print("Area of Circle=" + area);
    }
    
}

The output of Java Program to calculate area of circle

run:
Enter radius of circle=5
Area of Circle=78.53750000000001BUILD SUCCESSFUL (total time: 21 seconds)