5.7 第10周上机作业

1.编写一个方法，实现冒泡排序（由小到大），并调用该方法

package zy;
import java.util.Scanner;
public class w9 {

    public static void yy() {
           Scanner input=new Scanner(System.in);
           System.out.println("输入五个数");
           int x[]=new int [5];
           for(int i=0;i<x.length;i++){
               x[i]=input.nextInt();
           }
           for(int i=0;i<x.length-1;i++){
               for(int j=0;j<x.length-1-i;j++){
                   if(x[j]>x[j+1]){
                       int temp=x[j];
                       x[j]=x[j+1];
                       x[j+1]=temp;
                   }
               }
           }
           System.out.println("排序后为");
           for(int i=0;i<x.length;i++){
               System.out.println(x[i]);
           }
        }
        public static void main(String[] args){
            yy();
        }
}

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 zy;

public class w9 {

    public static int jc(int b) {
        int sum=1;
        for(int a=1;a<=b;a++){
            sum*=a;
        }
      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。[必做题]

package zy;
import java.util.Scanner;
public class w9 {

    public static void yyzm() {
        Scanner input=new Scanner(System.in);
        System.out.println("请输入年份");
        int year=input.nextInt();
        if(year % 4== 0 && year % 100 != 0 || year % 400 == 0 ){
            System.out.println("该年为闰年");
        }else{
            System.out.println("该年为平年");
        }
    }
    public static void main(String[] args){
        yyzm();
    }
           
}

4.课堂没完成的menu菜单，实现幸运抽奖功能

package zy;
import java.util.Random;
import java.util.Scanner;
public class w9 {

     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 a=input.nextInt();
            switch(a){
            case 1:
                login();
                break;
            case 2:
                reg();
                break;
            case 3:
                lucky();
            }
        }
        public 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
            Scanner input=new Scanner(System.in);
            System.out.println("输入一个四位数");
            Random r=new Random();
            int x=r.nextInt(10);
            int num =input.nextInt();
            while (num<100||num>10000){
                System.out.println("输入有误，重新输入");
                num=input.nextInt();
                if(num >= 1000 && num < 10000){
                    break;
                }
            }
            int bai =num%1000/100;
            if(bai==x){
                System.out.println("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();
        }
}