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

import java.util.Scanner;

public class Test2 {
    public static void PX() {
        System.out.println("请输入4个数字");
        Scanner input = new Scanner(System.in);
        int a[] = new int[4];
        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; 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) {
        PX();

    }
}
 

 

 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

import java.util.Scanner;

public class Test2 {
    public static void year() {
        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(year + "是闰年");
        else
            System.out.println(year + "是平年");
    }

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

 

 4.课堂没完成的menu菜单，实现幸运抽奖功能

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

public class Test2{

    /**
     * @param args
     */
    // 课堂没完成的menu菜单，实现幸运抽奖功能
    public static void mainmenu() {
        // 建立主菜单
        Scanner input = new Scanner(System.in);
        System.out.println("欢迎登录本系统");
        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:
            raffle();
            break;
        }
    }

    public static void login() {
        // 1.登录
        Scanner input = new Scanner(System.in);
        System.out.println("输入用户名");
        String uname = input.next();
        System.out.println("请输入密码");
        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 register() {
        // 2.注册
        Scanner input = new Scanner(System.in);
        System.out.println("输入用户名");
        String uname = input.next();
        System.out.println("请输入密码");
        String pwd = input.next();
        System.out.println("注册成功");
        returnMain();
    }

    public static void raffle() {
        // 3.抽奖
        Random r = new Random();
        int yu = r.nextInt(10);
        Scanner input = new Scanner(System.in);
        System.out.println("请输入四位会员号");
        int num = input.nextInt();
        int bai = num / 10 % 100;
        if (bai == yu) {
            System.out.println("是会员号");
        } else
            System.out.println("不是会员号");
        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 main(String[] args) {
        mainmenu();
    }

}