4.27

1.补充menu

import java.util.Random;
import java.util.Scanner;

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("请选择");
        int i = input.nextInt();
        switch (i) {
        case 1:
            login();
            break;
        case 2:
            zhuce();
            break;
        case 3:
            xingyuncj();
            break;
        case 4:
            xiaogushi();
            break;
        case 5:
            tuichu();
            break;
            
        }
    }

    public static void login() {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.println("输入用户名");
        String uname = input.next();
        System.out.println("输入密码");
        String upwd = input.next();
        if (uname.equals("zs") && upwd.equals("123")) {
            System.out.println("登录成功");
        } else {
            System.out.println("登录失败");
        }
        returnMain();
    
    }
    public static void zhuce() {
        Scanner input = new Scanner(System.in);
        System.out.println("用户名");
        String uname = input.next();
        System.out.println("密码");
        String upwd = input.next();
        if(uname.equals(null) || upwd.equals(null) ) {
            System.out.println("注册失败");
        }else {
            System.out.println("注册成功");
        }
        returnMain();
    }
    public static void xingyuncj() {
        System.out.println("1.作弊模式");
        System.out.println("2.正常模式");
        Scanner input = new Scanner(System.in);
        int x=input.nextInt();
        switch(x) {
        case 1:
            zuobi();
            break;
        case 2:
            zhengchang();
            break;
        }
    }
    public static void zuobi() {
        Scanner input = new Scanner(System.in);
        System.out.println("作弊模式：");
        Random r=new Random();
        int sjs=r.nextInt(10);
        System.out.println(sjs);
        System.out.println("请输入四位会员数");
        int num=input.nextInt();
        if(num/100%10==sjs) {
            System.out.println("恭喜你，是幸运会员");
        }else {
            System.out.println("祝你下次好运");
        }
        returnMain();
    }
    public static void zhengchang() {
        Scanner input = new Scanner(System.in);
        System.out.println("正常模式");
        Random r=new Random();
        int sjs=r.nextInt(10);
        System.out.println("请输入四位会员数");
        int num=input.nextInt();
        if(num/100%10==sjs) {
            System.out.println("恭喜你，是幸运会员");
        }else {
            System.out.println("祝你下次好运");
        }
        returnMain();
    }
    public static void xiaogushi() {
        System.out.println("把大象装进冰箱分成几个步骤");
        System.out.println("1.冰箱门打开");
        System.out.println("2.大象放进去");
        System.out.println("3.冰箱门关上");
        returnMain();
    }
    public static void tuichu() {
        System.out.println("是否退出系统Y/N");
        Scanner input = new Scanner(System.in);
        String a = input.next();
        if(a.equalsIgnoreCase("y")) {
            System.out.println("退出系统成功");
        }else {
            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5*4*3*2*1

public static int Jc(int n) {
            int cj=1;
            for (int i = 1; i <= n; i++) {
                cj*=i;
            }
            return cj;
        }
        public static void main(String[] args) {
            System.out.println(Jc(5));
        }
    }

3.编写一个方法 判断该年份是平年还是闰年

public static void Year(int n) {
    if (n % 4 == 0 && n % 100 != 0 || n % 400 == 0) {
        System.out.println(n + "是闰年");
    } else {
        System.out.println(n + "是平年");
    }
}
 
public static void main(String[] args) {
    Year y = new Year();
    Year(2023);
}