第八周作业 4.25

package Dmh;
import java.util.Random;
import java.util.Scanner;
public class zy425 {
    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");
            System.out.println("请选择");
            int i = input.nextInt();
            switch (i) {
            case 1:
                login();
                break;
            case 2:
                zhuce();
                break;
            case 3:
                choujiang();
                break;
            case 4:
                story();
                break;
            case 5:
                tc();
                break;

            }
        }
        public static void tc() {
            System.out.println("谢谢使用");
        }
        
        public static void story() {
            Scanner input = new Scanner(System.in);
            System.out.println("请选择想看的故事:");
            System.out.println("1.卖火柴的小女孩");
            System.out.println("2.小红帽");
            int m = input.nextInt();
            switch (m) {
            case 1:
                System.out.println("卖火柴的小女孩");
                break;
            case 2:
                System.out.println("小红帽");
                break;
            }
            returnMain();
        }

        private static void choujiang() {
            Scanner input = new Scanner(System.in);
            System.out.println("请输入四位会员卡号");
            int x = input.nextInt();
            Random r = new Random();
            int n = r.nextInt(10);
            if (x / 100 % 10 == n) {
                System.out.println("恭喜你中奖啦");
            } else {
                System.out.println("谢谢参与");
            }
            returnMain();
        }

        private static void zhuce() {
            Scanner input = new Scanner(System.in);
            System.out.println("请输入用户名");
            String name = input.next();
            System.out.println("请输入密码");
            String mima = input.next();
            System.out.println("请再次输入密码");
            String mima = input.next();
            System.out.println("注册成功");
            returnMain();
        }

        private static void login() {
            Scanner input = new Scanner(System.in);
            System.out.println("请输入用户名");
            String uname = input.next();
            System.out.println("请输入密码");
            String upwd = input.next();
            if (uname.equals("nnn") && upwd.equals("568")) {
                System.out.println("登录成功");
            } else {
                System.out.println("登录失败");
            }
            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 Dmh;
 
import java.util.Scanner;
 
public class zy458 {
    private static int jc(int x)
    {
        int sum = 1;
        for (int i = x; i > 0; i--)
        {
            sum *= i;
        }
        return sum;
    }
    public static void main(String[] args) {
        Scanner input= new Scanner(System.in);
        System.out.println("请输入数字：");
        int i=input.nextInt();
        System.out.println("阶乘等于："+jc(i));
    }
}
3.编写一个方法，判断该年份是平年还是闰年
package Dmh;
 
import java.util.Scanner;
 
public class zy425 {
    private static boolean run(int year)
    {
        return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
    }
    public static void main(String[] args) {
        System.out.println("请输入一个年份");
        Scanner s = new Scanner(System.in);
        if (run(s.nextInt()))
        {
            System.out.println("是闰年");
        }
        else
        {
            System.out.println("不是闰年");
        }
    }
}