Java第十次作业

1.编写一个方法，实现冒泡排序（由小到大），并调用该方法

package homework10;

import java.util.Scanner;

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

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 homework10;

public class jc {
    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(5));
    }
}

3.编写一个方法，判断该年份是平年还是闰年

package homework10;

public class work3 {
    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(2021));
           }
        
    }

4.课堂没完成的menu菜单，实现幸运抽奖功能

package homework10;

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

public class Work4 {
    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 c = number / 100 % 10;
        Random r = new Random();
        int a = (int) r.nextInt(10);
        if (c == a) {
            System.out.println("是幸运会员");
        } else {
            System.out.println("不是幸运会员");
        }
        returnMain();
    }

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

}