Java第十次作业

1编写一个方法，实现冒泡排序法（由小到大），并调用该方法

import java.util.Scanner;


public class txt2 {
        public static void txt2() {
            Scanner input = new Scanner(System.in);
            System.out.println("请输入数组");
            int []a=new int [5];
            for(int i=0;i<a.length;i++){
                a[i]=input.nextInt();
                
            }
            for(int i=0;i<a.length-1;i++){
                for(int j=0;j<a.length-1-i;j++){
                    if(a[j]>a[j+1]){
                        int temp=a[j];
                        a[j]=a[j+1];
                        a[j+1]=temp;
                    }
                }
            }
            for(int i:a){
                System.out.println(i);
            }
        }
            public static void main(String[] args){
                txt2();
        }
}

2编写一个方法，求n的阶乘；

public class work6 {
  public static int jc(int n){
    int sum=1;
    for(int i=1;i<=n;i++){
        sum=sum*i;
    }
    return sum;
  }

public static void main(String[] args){
    System.out.println(jc(6));
   }
}

3 编写一个方法，判断该年份是平年还是闰年。

public class work6 {
  public static int pr(int n){
    if(n%4==0&&n%100!=0||n%400==0)
        System.out.println("是闰年");
    else
        System.out.println("是平年");
    return n;
  }

public static void main(String[] args){
    System.out.println(pr(2020));
   }
}

4 课堂没有完成的menu菜单，实现幸运抽奖功能

import java.util.Random;
import java.util.Scanner;
public class work7 {
    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.退出系统");
        System.out.println("请选择：");
        int i = input.nextInt();
        switch (i) {
        case 1:
            login();
            break;
        case 2:
            register();
            break;
        case 3:
            xycj();
            break;
        }
    }

    public static void register() {
        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 pwd = input.next();
        System.out.println("注册成功");
        returnMain();

    }

    public static void returnMain() {
        Scanner input = new Scanner(System.in);
        System.out.println("是否返回主菜单？Y/N");
        if (input.next().equalsIgnoreCase("Y"))
            mainMenu();
        else
            System.out.println("谢谢使用");
    }

    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 pwd = input.next();
        if (uname.equals("admin") && pwd.equals("admin"))
            System.out.println("成功");
        else
            System.out.println("失败");
        returnMain();

    }
    
    public static void xycj() {
        Scanner input = new Scanner(System.in);
        System.out.println("输入一个4位会员卡号");
        int number = input.nextInt();
        int bw = number / 100 % 10;
        Random r = new Random();
        int a = (int) r.nextInt(10);
        if (bw == a) {
            System.out.println("该用户是幸运会员");
        } else {
            System.out.println("该用户不是幸运会员");
        }
        returnMain();
    }
    
    public static void main(String[] args) {
        mainMenu();
    }
}