Java Programs

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Introduction to Java

Area of a circle - Java Program

Formula used:

Area = π × r²

Where:

• π (pi) = 3.14159 (or Java’s Math.PI)
• r = radius of the circle

import java.util.Scanner;
 
public class AreaOfCircle {
    public static void main(String[] args) {
 
        Scanner sc = new Scanner(System.in);
 
        // Taking radius input
        System.out.print("Enter the radius of the circle: ");
        double radius = sc.nextDouble();
 
        // Calculating area using formula
        double area = Math.PI * radius * radius;
 
        // Displaying area
        System.out.println("The area of the circle is: " + area);
 
        sc.close();
    }
}
 

 
OUTPUT 1:
Enter the radius of the circle: 5
The area of the circle is: 78.53981633974483

OUTPUT 2:
Enter the radius of the circle: 2.5
The area of the circle is: 19.634954084936208

Explanation

Step 1 — Input radius

double radius = sc.nextDouble();

Accepts radius as a floating-point number.

Step 2 — Apply Area Formula

double area = Math.PI * radius * radius;

• Math.PI gives the most accurate value of π
• radius * radius computes r²
• Final result stored in area

Step 3 — Display the Area

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