Java/Module 1: Basic Java Programs/Program

Area of Circle

Calculate the area of a circle given its radius.

JavaBeginner

Java

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter radius: ");
        double r = sc.nextDouble();

        double area = Math.PI * r * r;
        System.out.println("Area of circle = " + area);

        sc.close();
    }
}

Output

Enter radius: 5
Area of circle = 78.53981633974483

We use the formula area = πr² and Java's built-in Math.PI constant.

Positive or Negative Number

Area of Rectangle