diff --git a/Factorial.java b/Factorial.java index a3b4052ed..b7cc906ae 100644 --- a/Factorial.java +++ b/Factorial.java @@ -1,10 +1,11 @@ +package factorial; import java.util.Scanner; /** * This program will print out the factorial of any non-negative * number that you input into it. * - * @author Unknown + * @author Marcus * */ public class Factorial{ @@ -15,24 +16,27 @@ public class Factorial{ * @param args Command line arguments */ public static void main(String[] args){ - Scanner input = new Scanner(System.in); - //Prompt user to enter integer - System.out.print("Enter a non-negative integer: "); - - //Proceed with factorial calculation only if inputted number is not negative - if(input.hasNextInt()){ - int number = input.nextInt(); - if (number < 0){ - System.out.print("Cannot execute. Please enter a non-negative integer: "); - number = input.nextInt(); - } else { - //Output of factorial for any non-negative number - System.out.println("The factorial of "+number+" will yield: "+factorial(number)); - } - } - input.close(); - } - + Scanner input = new Scanner(System.in); + System.out.print("Enter a non-negative integer: "); + + //If user does not enter an Integer, we want program to fail gracefully, letting the user know why it terminated + try{ + int number = input.nextInt(); + + //We keep prompting the user until they enter a positive number + while(number < 0){ + System.out.println("Your input must be non-negative. Please enter a positive number: "); + number = input.nextInt(); + } + //Display the result + System.out.println("The factorial of " + number + " will yield: " + factorial(number)); + + }catch(Exception e){ + System.out.println("Error: You did not enter an integer. Program has terminated."); + } + input.close(); + } + /** * Recursive Factorial Method * @@ -40,14 +44,7 @@ public class Factorial{ * @return The factorial of the number */ public static long factorial(int n){ - - if (n==0){ - return 1; - } else if (n==1){ - return 1; - } else { - return n * factorial(n-1); - } - + if(n == 0 || n == 1) return 1; + return n * factorial(n - 1); } -} \ No newline at end of file +}