第八周作业

1.补充menu。

package as;
import java.util.Scanner;
import java.util.Random;
public class unll {    
    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,输入四位会员卡号,如果百位等于系统随机数,就是星运会员.否则不是.");
        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:
            choujiang();break;
        case 4:
            gushi();break;
        case 5:
            System.out.println("退出系统");
        default:
            System.out.println("输入错误！");
            returnMain();break;
        }
    }
    private 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();
    }
    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 pwd=input.next();
        if(name.equals("zs")&&pwd.equals("123")) {
            System.out.println("注册成功");
        }else {
            System.out.println("注册失败");
        }
        returnMain();
    }
    private static void choujiang() {
        Scanner input=new Scanner(System.in);
        Random r=new Random();
        System.out.println("请输入一个四位数：");
        int a=input.nextInt();
        int b=r.nextInt(10);
        if(a/100%10==b) {
            System.out.println("幸运会员");
        }else {
            System.out.println("很遗憾您不是幸运会员");
        }
        returnMain(); 
    }
    private static void gushi() {
        Scanner input=new Scanner(System.in);
        System.out.println("请选择您要看的小故事：1.白雪公主；2.丑小鸭");
        int c=input.nextInt();
        switch(c) {
        case 1:
            System.out.println("很久很久以前……");break;
        case 2:
            System.out.println("在夏日的……");break;
        default:
            System.out.println("");break;
        }
        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 as;
import java.util.Scanner;
public class Constructor {
    public static int jc(int a){
        int sum=1;
        for (int i = 1; i <=a; i++) {
            sum*=i; 
        }
        return sum;
    }
    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。

package as;

public class Constructor {
     public static void main(String[] args) {
         near(2102);
     }
     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");
             }
     }
}