/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.basics;/** * This class doesn't define a main() method, so it isn't a program by itself. * It does define a useful method that we can use in other programs, though. **/public class Factorial {    /** Compute and return x!, the factorial of x */    public static int factorial(int x) {	if (x < 0) throw new IllegalArgumentException("x must be >= 0");        int fact = 1;        for(int i = 2; i <= x; i++)    // loop            fact *= i;                 // shorthand for: fact = fact * i;        return fact;    }}