Java递归实现阶乘

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("请输入一个正整数（输入0退出循环）：");
            try {
                n = sc.nextInt();
            } catch (Exception e) {
                System.out.println("错误的类型！");
                sc.nextLine();
                continue;
            }
            if (n == 0) {
                break;
            }
            System.out.printf("%d! = %d\n", n, fact(n));
        }

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

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

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