computer_programming.java

import java.util.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class computer_programming{
	public static void main(String[] args) { 
 
 /*hello there */
 int radius=0;
 System.out.println("Please enter radius of a circle"); 
 try{

 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 radius = Integer.parseInt(br.readLine());
 
 }catch(NumberFormatException ne){
 System.out.println("Sorry, invalid number"+ne);
 System.exit(0);
 }catch(IOException ioe){
 System.out.println("IO Error"+ioe);
 System.exit(0);
 
 }
 
 // we use Math.PI to get the value of 3.14
 //circle area = PI*radius*radius
 double area = Math.PI * radius * radius;
 System.out.println("the area = "+ area);
 }

 }