利用递归!

package com.demo09;

import java.util.Scanner;

public class demo01 {
    public static void main(String[] args) {
        //阶乘的计算
        System.out.println("请输入计算的阶乘:");
        Scanner sc = new Scanner(System.in);
        int f = sc.nextInt();
        int sum = factorial(f);
        System.out.println("sum="+sum);
    }

    public static int factorial(int fa) {
        if(fa==1){
            return 1;
        }
        return fa*factorial(fa-1);
    }
}