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 test;

public class Lwk38 {
    public static void maopao(int[] x) {
        for (int i = x.length - 1; i > 0; i--) {
            for (int j = 0; j < i; j++) {
                if (x[j] > x[i]) {
                    int a = x[j];
                    x[j] = x[i];
                    x[i] = a;
                }
            }
        }
    }

    public static void main(String[] args) {
        int[] x = { 4, 5, 2, 7, 8, 3, 1, 6, 9 };
        maopao(x);
        for (int i : x) {
            System.out.println(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 test;

import java.util.Scanner;

public class Lwk39 {
    public static int jiecheng(int x) {
        int sum = 1;
        for (int i = 1; i <= x; i++) {
            sum *= i;
        }
        return sum;
    }

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("请输入n");
        int n = input.nextInt();
        System.out.println("n的阶乘为");
        System.out.println(jiecheng(n));
    }
}

3.编写一个方法，判断该年份是平年还是闰年。[必做题]

package test;

import java.util.Scanner;

public class Lwk40 {
    public static void panduan(int y) {
        if (y % 4 == 0 && y % 100 != 0 || y % 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("请输入年份");
        int y = input.nextInt();
        panduan(y);
    }
}

4.课堂没完成的menu菜单，实现幸运抽奖功能

package test;

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

public class Lwk41 {
    Scanner input = new Scanner(System.in);

    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):
            luckly();
            break;

        }
    }

    public static void returnMenu() {
        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");
        }
    }

    private 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("wck") && upwd.equals("1919")) {
            System.out.println("ok");
        } else {
            System.out.println("fail");
        }
        returnMenu();
    }

    private 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("再次输入密码");
        String uppwd = input.next();
        if (upwd.equals(input()) == uppwd.equals(input())) {
            System.out.println("注册成功");
            System.out.println("用户名" + uname + "密码" + upwd);
        } else {
            System.out.println("密码错误");
        }
        returnMenu();
    }

    private static Object input() {
        // TODO Auto-generated method stub
        return null;
    }

    private static void luckly() {
        Scanner input = new Scanner(System.in);
        Random r = new Random();
        int luck = r.nextInt(10);
        System.out.println("输入四位数会员卡号");
        int id = input.nextInt();
        if (luck == id) {
            System.out.println("幸运会员");
        } else {
            System.out.println("不是幸运会员");
        }
        returnMenu();
    }

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

    }
}