Chapter 11, Problem 3P

Program plan:

• Import required packages
• Define the class “Factorial”.
• Define the class “main”
  • Create an object for scanner class.
  • Get the value form the user.
  • Check whether the user enters “Y” or “y”.
    • Assign “-1” to “num”.
    • Check whether the “num” is less than “0”.
      • Get the input value form the user.
      • Get the number from the user.
    • Print the result by calling the method “factorial()”.
    • Get the choice from the user.
• Define the method “factorial()”.
  • Check whether “n” equals to “1” or “0”.
    • Return the value “1”.
  • Otherwise, call the method “factorial()”.

Program:

//Import required package

import java.util.*;

//Definition of class "Factorial"

public class Factorial

{

    //Definition of method "main"

    public static void main(String[] args)

    {

        //Crete an object for scanner class

        Scanner sc = new Scanner(System.in);

        //Get the value from the user

        char choice = 'y';

        //check whether the user enters "Y" or "y"

        while(choice == 'y' || choice == 'Y')

        {

            //Assign "-1" to num

            int num = -1;

/*check whether the "num" is less than "0"*/

            while(num < 0)

            {

    /*Get the valid input from the user*/

    System...