JAVA 10

1.编写一个方法，实现冒泡排序（由小到大），并调用该方法

package G1;

public class G1 {
    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 G1;

public class G2 {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
         int sum1=jc(10);
            System.out.println(sum1);
        }
        public static int jc(int n){
            int sum=1;
            for (int i =1; i <=n; i++) {
                sum*=i;
            }
            return sum;
    }
}

3.编写一个方法，判断该年份是平年还是闰年。[必做题]

package G1;

import java.util.Scanner;

public class G3 {
    public static void main(String[] args) {
         nian();
        }

        public static void nian() {
            try (Scanner input = new Scanner(System.in)) {
                System.out.println("输入年份");
                int year = input.nextInt();
                if (year % 4 == 0 && year % 100 != 100 || year % 400 == 0) {
                    System.out.println("该年份为闰年");
                } else {
                    System.out.println("该年份是平年");
                }
            }
        }
}

4.课堂没完成的menu菜单，实现幸运抽奖功能

package G1;

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

public class G4 {
    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();

        }

    }

    public 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("输入一个四位数");
        Random r = new Random();
        int x = r.nextInt(10);
        int num = input.nextInt();
        while (num < 1000 || num > 10000) {
            System.out.println("输入有误,重新输入");
            num = input.nextInt();
            if (num >= 1000 && num < 10000) {
                break;
            }
        }
        int bai = num % 1000 / 100;
        if (bai == x) {
            System.out.println("幸运会员");
        } else {
            System.out.println("不是幸运会员");
        }

        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() {
        // TODO Auto-generated method stub
        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();
    }
}