Java再帰実装階乗

import java.util.Scanner;

public class Factorial {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n;

        while (true) {
            System.out.print("        （  0    ）：");
            try {
                n = sc.nextInt();
            } catch (Exception e) {
                System.out.println("     ！");
                sc.nextLine();
                continue;
            }
            if (n == 0) {
                break;
            }
            System.out.printf("%d! = %d
", n, fact(n));
        }

        System.out.println("  !");
    }

    private static long fact(int n) {
        if (n < 0) {
            System.out.println("       ！");
            return -1;
        } else {
            return factorial(n);
        }
    }

    private static long factorial(int n) {
        if (n == 1) {
            return 1;
        } else {
            return n * factorial(--n);
        }
    }
}

 
Java再帰実装階乗