第十周java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 ktlx;

import java.util.Scanner;

public class MaoPaoPaiXu {
    public static void px() {
        Scanner input = new Scanner(System.in);
        int[] a = new int[5];
        System.out.println("输入五数");
        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;
                }
            }
        }
        System.out.println("排序后:");
        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 homework9;

public class Text2 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int sum=getSum(5);
        System.out.println(sum);

    }

    private static int getSum(int n) {
        // TODO Auto-generated method stub
        if(n==1){
            return 1;
        }
        int x=getSum(n-1);
        return x*n;
    }

}

　　

3.编写一个方法，判断该年份是平年还是闰年。

import java.util.Scanner;

//编写一个方法，判断该年份是平年还是闰年。[必做题]
public class NianFen {
        public static void pr(int year){
            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) {
        Scanner input=new Scanner(System.in);
        System.out.println("输入年份");
        pr(input.nextInt());
        }
}

　　

4.课堂没完成的menu菜单，实现幸运抽奖功能

package mtbox;

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

public class zuoye9 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        mainMenu();
    }
     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("yes"))
                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("ls") && upwd.equals("123")) {
                System.out.println("ok");
            } else {
                System.out.println("fail");
         }
            returnMain();
    }
}