# Java Program to Find Area of a Circle

The formula for finding area of a circle is,

area = PI * radius * radius

Where PI is a constant (approximately 3.1416) and radius is the radius of the circle.

## Calculate Area of a Circle in Java

The following Java program calculates the area of a circle given the radius of the circle. This program demonstrates a number of key concepts in Java programming,

- How to obtain user input from console
- How to write output to console
- How to use IO classes and decorator pattern
- Using library classes such as Math, BufferedReader, Double etc.
- Performing mathematical calculations

// Java program to calculate area of a circle import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; public class CircleArea { public static void main(String[] args) throws IOException{ BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); System.out.print("Please enter the radius of the circle : "); double radius = Double.parseDouble(reader.readLine()); double area = Math.PI * radius * radius; System.out.println("Area of the circle with radius "+radius+" is : "+area); } }

import java.util.Scanner;

class Circle

{

public static void main(String[] args)

{

Scanner sc=new Scanner(System.in);

System.out.println(“plz enter a radius”);

int i=sc.nextInt();

System.out.println(“area of Circle=”+3.14*i*i);

}

}