Finding the Factorial

The factorial of a number (written as n!) is defined as the product of the integers between 1 and n. For example: 4! = 1 * 2 * 3 * 4 = 24. By definition, 0! = 1. The factorial is not defined for negative numbers.

Write a Java program that asks the user for a non-negative integer and computes and prints the factorial of that number. Your code should verify that the number entered is nonnegative. The code should also produce the value of 1 if 0 is entered as the number.

Your program should include:

The Scanner class for input

While or do while loops for input validation

A while loop to compute the factorial

Samples of the output is shown below:

Output 1:

Please enter a nonnegative integer: -5 Factorial is undefined for negative numbers. Please enter a non-negative integer: 5 5! = 120

Output 2:

Please enter a nonnegative integer: 0 0! = 1