JAVA第九次作业

1.编写一个方法，实现冒泡排序（由小到大），并调用该方法

package home;

public class ZUOYE {
     public static void maopao(int a[]) {
            for (int i = 0; i < a.length - 1; i++) {
                for (int j = 0; j < a.length - i - 1; j++) {
                    if (a[j] > a[j + 1]) {
                        int temp = a[j];
                        a[j] = a[j + 1];
                        a[j + 1] = temp;
                    }
                }
            }
        }
     
        public static void main(String[] args) {
            int b[] = {5,6,4,3,7,2,8,1,9};
            maopao(b);
            for (int i = 0; i < b.length; i++) {
                System.out.println(b[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 home;

public class ZUOYE {
    public static int jc(int a){
        int sum=1;
        for (int i = 1; i < a+1; 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。[必做题]

package home;

import java.util.Scanner;

public class ZUOYE {
    public static void nf(int year) {
        if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
            System.out.println("是闰年");
        } else {
            System.out.println("是平年");
        }
    }
 
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("输入年份");
        nf(input.nextInt());
    }
}

 

 

4.课堂没完成的menu菜单，实现幸运抽奖功能

 

package home;

    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
            Scanner input=new Scanner(System.in);
            System.out.println("输入四位会员号");
            int b=input.nextInt();
            Random  r=new Random();
            int a=r.nextInt(10);
            if (b%1000/100==a) {
                System.out.println("是幸运用户");
            }else{
                System.out.println("不是幸运用户");
            }
            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() {
            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();

        }
        

    }