Question

/*
* Author :
* Purpose: This program calculates the factorial of an input number.
(Factorial.java)
*/
import java.util.Scanner;
public class Factorial
{
public static void main(String[] args)
{
Scanner input=new Scanner(System.in);
int number;
Factorial factObj=new Factorial();
//1. Input a positive integer number
do
{
System.out.print("Enter a positive integer number: ");
number=input.nextInt();
if (number<0)
System.out.println("Error: Invalid number.");
}while (number<0);