第九次作业（第十周5.7）

1.编写一个方法，实现冒泡排序（由小到大），并调用该方法

package week10;

import java.util.Scanner;

public class paixu {
    public static void n(int a[]) {
        for (int i = 0; i < a.length; i++) {
            for (int j =i+1; j < a.length; j++) {
                if (a[i]>a[j]) {
                    int temp=a[i];
                    a[i]=a[j];
                    a[j]=temp;
                }
            }
        }
    }    
    public static void main(String[] args) {
     int a[]=new int[5];
     Scanner b=new Scanner(System.in);
     System.out.println("请输入5个整数");
     for (int i = 0; i < a.length; i++) {
        a[i]=b.nextInt();
    }
     System.out.println("排序前：");
     for (int i = 0; i < a.length; i++) {
         System.out.print(a[i]+" ");
    }
     n(a);
     System.out.println();
     System.out.println("排序后：");
     for (int i = 0; i < a.length; i++) {
        System.out.print(a[i]+" ");
    }
             
    }

}

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。 [必做题]

package week10;

public class jiecheng {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int sum=getSum(5);
        System.out.println("阶乘="+sum);
    }

    private static int getSum(int n) {
        // TODO Auto-generated method stub
        if(n==1){
            return 1;
        }
        int temp=getSum(n-1);
        return temp*n;
    
    }

}

3.编写一个方法，判断该年份是平年还是闰年。[必做题]

package week10;

import java.util.Scanner;

public class panduan {
     public static void main(String[] args) {
            year();
        }

        private static void year() {
            Scanner input=new Scanner(System.in);
            System.out.println("输入年份");
            int a=input.nextInt();
            if (a%4==0&&a%100!=0||a%400==0) {
            System.out.println("是闰年");
            } 
            else {
                    System.out.println("不是闰年");
            }
}
}

4.课堂没完成的menu菜单，实现幸运抽奖功能

package week10;

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

public class Menu {
    public static void mainMenu(){
        Scanner input=new Scanner(System.in);
        System.out.println("欢迎使用本系统");
        System.out.println("1.登录");
        System.out.println("2.注册");
        System.out.println("3.幸运抽奖");
        System.out.println("4.退出");
        System.out.println("请选择");
        int i=input.nextInt();
        switch(i){
        case 1:
            login();
            break;
        case 2:
            reg();
            break;
        case 3:
            lucky();    
        }    
    }    
    private static void lucky() {
        // 输入四位会员卡号，如果百位数等于随机数，幸运会员。否则不是。同时也要询问是否返回主菜单
        Random r=new Random();
        int a=r.nextInt(10);
        System.out.println("("+a+")");
        Scanner input=new Scanner(System.in);
        System.out.println("输入四位会员卡号"); 
        int kahao= input.nextInt();
        while (kahao < 1000 || kahao > 10000) {
            System.out.println("输入错误,重新输入");
            kahao = input.nextInt();
            if (kahao >= 1000 && kahao < 10000) {
                break;
            }
        }
        int bai=kahao%1000/100;
        if (bai == a) {
            System.out.println("是幸运会员");
        } else {
            System.out.println("不是幸运会员");
        }

        returnMain();
    }


    public static void returnMain(){
        Scanner input=new Scanner(System.in);
        System.out.println("是否返回主菜单？");
        if(input.next().equalsIgnoreCase("Y"))
            mainMenu();
        else
            System.out.println("谢谢使用");
    }
    
    public static void reg() {
        // TODO Auto-generated method stub
        Scanner input=new Scanner(System.in);
        System.out.println("输入要注册的用户名");
        String uname=input.next();
        System.out.println("输入注册密码");
        String upwd=input.next();
        System.out.println("注册成功");
        returnMain();
        
        
    }


    public static void login(){
        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("ok");
        }else{
            System.out.println("fail");
        }
        returnMain();        
    }
    

    
    public static void main(String[] args) {
        mainMenu();

    }
}