149e5d2abc
The factorial method can be simplified to 2 lines, which I believe is easier to read. Also, in previous version, if user enters two negative numbers back to back, the program crashes. We need a while loop to prompt the user until they actually enter the correct input, instead of only prompting them once. Also, if user enters a character instead of an integer, program crashes with no error message. We should fail more gracefully.
51 lines
1.4 KiB
Java
51 lines
1.4 KiB
Java
package factorial;
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import java.util.Scanner;
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/**
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* This program will print out the factorial of any non-negative
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* number that you input into it.
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*
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* @author Marcus
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*
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*/
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public class Factorial{
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/**
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* The main method
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*
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* @param args Command line arguments
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*/
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public static void main(String[] args){
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Scanner input = new Scanner(System.in);
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System.out.print("Enter a non-negative integer: ");
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//If user does not enter an Integer, we want program to fail gracefully, letting the user know why it terminated
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try{
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int number = input.nextInt();
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//We keep prompting the user until they enter a positive number
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while(number < 0){
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System.out.println("Your input must be non-negative. Please enter a positive number: ");
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number = input.nextInt();
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}
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//Display the result
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System.out.println("The factorial of " + number + " will yield: " + factorial(number));
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}catch(Exception e){
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System.out.println("Error: You did not enter an integer. Program has terminated.");
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}
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input.close();
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}
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/**
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* Recursive Factorial Method
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*
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* @param n The number to factorial
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* @return The factorial of the number
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*/
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public static long factorial(int n){
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if(n == 0 || n == 1) return 1;
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return n * factorial(n - 1);
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}
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}
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