Recursion using function

Recursion program is very easy .
It is used in many puzzle like tower of hanoi ,traversing a tree etc.
the below program is to  calculate factorial of a number.

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

 class Recusion
{
public static void main(String[] args) throws NumberFormatException, IOException
{
System.out.println("enter a number");
BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
int i=Integer.parseInt(reader.readLine());
Recusion recusion=new Recusion();
System.out.println("Factorial :"+recusion.factorial(i));
}
int factorial(int i)
{
if(i==0)
{
return 1;
}
else
{
return i*factorial(i-1);
}
}

}