第八周作业

1.完善menu的注册功能，抽奖以及讲小故事等功能。
package hua;
import java.util.Scanner;
import java.util.Random;
public class menu {
 
    public static void main(String[] args) {
        mainMenu();
     }
     public static void mainMenu() {
      Scanner input =new Scanner(System. in);
      System.out.println("1.登录");
      System.out.println("2.注册");
      System.out.println("3.幸运抽奖");
      System.out.println("4.看小故事");
      System.out.println("5.退出系统");
      System.out.println("***************************");
      System.out.println("请选择");
      int i = input.nextInt();
      switch (i){
      case 1:
       register();
       break;
      case 2:
       login();
       break;
      case 3:
          cj();
       break;
      case 4:
       story();
       break;
      case 5:
       returnmain();
       break;
      }
     }
     public static void register() {
      Scanner input = new Scanner(System.in);
      System.out.println("输入用户姓名");
      String uname=input.next();
      System.out.println("输入密码");
      String upwd=input.next();
      if(uname.equals("zs")&& upwd.equals("12321")){
       System.out.println("登录成功");
      }else{
       System.out.println("登录失败");
      }
      returnmain();
     }
     public static void login(){
      Scanner input = new Scanner(System.in);
      System.out.println("注册姓名");
      String zname=input.next();
      System.out.println("注册密码");
      String zpwd=input.next();
      System.out.println("注册成功！");
      returnmain();
     }
     public static void cj(){
      Random r=new Random ();
      Scanner input=new Scanner(System.in);
      System.out.println("请输入四位会员号");
      int huiyuan=input.nextInt();
      int bai=huiyuan/100%10;
      int lucky=r.nextInt(10);
      if(bai==lucky){
       System.out.println("您是幸运会员");
      }else{
       System.out.println("您不是幸运会员");
      }
      returnmain();
     }
     public static void story(){
       System.out.println("一人一马，仗剑天涯！");
      returnmain();
     }
     public static void returnmain(){
      System.out.println("是否返回主菜单Y/N");
      Scanner input=new Scanner(System.in);
      if(input.next().equalsIgnoreCase("Y")){
       mainMenu();
      }else{
       System.out.println("谢谢使用");
      }
     }
     }

2.编写一个方法，求整数n的阶乘，例如5的阶乘是1*2*3*4*5。
package demo01;
import java.util.*;
public class demo001 {
    public static void main(String[] args) {
        int sum=1;
        Scanner jc = new Scanner(System.in);
        System.out.println("请输入一个整数：");
        int k = jc.nextInt();
        for (int i = 1; i <= k; i++) {
            sum=sum*i;
        }
        System.out.println(k+"的阶乘为："+sum);
    }
}
3.编写一个方法，判断该年份是平年还是闰年。
package zuoye11;

public class zuoye11 {
    public static void main(String[] args) {
        near(2020);
    }
        public static void near(int y){
             if (y % 4 == 0 && y % 100 != 0 || y % 400 == 0) {
                    System.out.println(y + "年是闰年");
                } else {
                    System.out.println(y + "年不是闰年");
                }
        }

}