Java Program To Calculate And Display The Area Of A Circle

Program 1: Using Scanner Class

 //importing java package
import java.util.Scanner;

 public class CircleArea3{
  public static void main (String[] args){

     //creating new Scanner
    Scanner sc = new Scanner (System.in);

     System.out.println ("Please enter the radius of the circle:\n");
    double radius = sc.nextDouble();

     //calculate area of circle
    double pi = 3.14;
    double area = pi * (radius * radius);

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

Save this file as 'CircleArea3.java'
Compile: $javac CircleArea3.java
Execute: $java CircleArea3
Output:

 Please enter the radius of the circle:

 6
Area of the circle is: 113.04


Program 2: Using BufferedReader Class

//importing java packages
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

 public class CircleArea4{
  public static void main (String[] args)
  throws IOException{

     //creating new InputStreamReader
    InputStreamReader is = new InputStreamReader (System.in);
    //creating new BufferedReader
    BufferedReader br = new BufferedReader (is);

     System.out.println ("Please enter the radius of the circle:\n");
    double radius = Double.parseDouble (br.readLine());

     //calculate area of circle
    double pi = 3.14;
    double area = pi * (radius * radius);

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

Save this file as 'CircleArea4.java'
Compile: $javac CircleArea4.java
Execute: $java CircleArea4
Output:

 Please enter the radius of the circle:

 12
Area of the circle is: 452.16