java第12次作业

1.编写程序

package homework;
import java.util.Random;
import java.util.Scanner;
public class menu {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        mainmenu();

    }
     public static void mainmenu() {
            Scanner input = new Scanner(System.in);
            System.out.println("****************");
            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.print("请选择:");
            int i = input.nextInt();
            switch (i) {
            case 1:
                login();
                break;
            case 2:
                register();
                break;
            case 3:
                luck();
                break;
            case 4:
                story();
                break;
            case 5:
                exit();
                break;
            default:
                System.out.println("该系统暂未开放其它功能！");
                break;


     }
}
     private static void login() {
            // TODO Auto-generated method stub
            Scanner input = new Scanner(System.in);
            System.out.print("请输入您的用户名：");
            String uname = input.next();
            System.out.print("请输入您的密码：");
            String upwd = input.next();
            if (uname.equals("zj") && upwd.equals("0909")) {
                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");
            }
     
        }
     
        public static void register() {
            Scanner input = new Scanner(System.in);
            System.out.print("请输入您的用户名:");
            String uname = input.next();
            System.out.print("请输入您的密码：");
            String upwd = input.next();
            System.out.println("您的账号已注册成功！！！");
            returnMain();
        }
     
        public static void luck() {
            System.out.println("**************************************欢迎来到幸运抽奖界面！*************************************");
            System.out.println(" *******规则为：如果您输入的四位会员卡号的百位等于系统随机数,您将成为我们的幸运会员,否则不是*******");
            Scanner input = new Scanner(System.in);
            int temp = 0;
            for (int i = 0;; i++) {
                System.out.print("请您输入四位的会员卡号：");
                int vipcard = input.nextInt();
                int bai = vipcard % 1000 / 100;
                temp = bai;
                if (vipcard < 999 || vipcard > 9999) {
                    System.out.println("您的会员卡号错误,请您重新输入！");
                } else {
                    break;
                }
            }
            Random r = new Random();
            int num = r.nextInt(9);
            System.out.println("系统生成的百位随机数为：" + num);
            if (num == temp) {
                System.out.println("恭喜您,成为我们的幸运会员！");
            } else {
                System.out.println("很遗憾,感谢您的参与！");
            }
            returnMain();
        }
     
        public static void story() {
            System.out.println("请您输入相应的数字(1-3)观看小故事！");
            for (int i = 0;; i++) {
                Scanner input = new Scanner(System.in);
                int num = input.nextInt();
                switch (num) {
                case 1:
                    System.out.println("灰姑娘");
                    break;
                case 2:
                    System.out.println("鼓手");
                    break;
                case 3:
                    System.out.println("格林童话");
                    break;
                default:
                    System.out.println("您的输入有错,请重新输入！");
                }
                break;
            }
            returnMain();
        }
     
        public static void exit() {
            System.out.println("是否退出该系统?Y/N");
            Scanner input = new Scanner(System.in);
            if (input.next().equalsIgnoreCase("N")) {
                mainmenu();
            } else {
                System.out.println("您已退出我们的系统,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

package one;

public class jc {

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(7));
}

3. 编写一个方法 判断该年份是平年还是闰年

package one;

public class Year {
    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(2000);
    }

}