/**
 * Title:        Chapter 4, "Methods"
 * Description:  Examples for Chapter 4
 * Copyright:    Copyright (c) 2000
 * Company:      Armstrong Atlantic State University
 * @author Y. Daniel Liang
 * @version 1.0
 */

// ComputeFactorial.java: Compute factorial of an integer
// package chapter4

public class ComputeFactorial
{
  public static void main(String[] args)
  {
    // Prompt the user to enter an integer
    System.out.println("Please enter a nonnegative integer");
    int n = MyInput.readInt();

    System.out.println("Factorial of " + n + " is " + factorial(n));
  }

  /**Recursive method for computing factorial of n*/
  static long factorial(int n)
  {
    if (n == 0) // Stopping condition
      return 1;
    else
      return n*factorial(n-1); // Call factorial recursively
  }
}


// a class for reading various types from the keyboard (System.in) 
class MyInput
{
    public static String readString()
    {
        String string = "";
        java.io.BufferedReader bufferedReader = 
           new java.io.BufferedReader(new java.io.InputStreamReader(System.in));
        try
        {
            string = bufferedReader.readLine();
        }
        catch (java.io.IOException ex)
        {
            throw new RuntimeException(ex);
        }
        return string;
    }

    public static int readInt()
    {
        return Integer.parseInt(readString());
    }

    public static double readDouble()
    {
        return Double.parseDouble(readString());
    }

    // test all the methods of this class
    public static void main(String[] args)
    {
        System.out.println("Testing 'readString()'");
        System.out.print("Input your string : ");
        System.out.println("Your string was '" + readString() + "'");
        System.out.println("\nTesting 'readInt()'");
        System.out.print("Input your int : ");
        System.out.println("Your int was '" + readInt() + "'");
        System.out.println("\nTesting 'readDouble()'");
        System.out.print("Input your double : ");
        System.out.println("Your double was '" + readDouble() + "'");
    }
}