Java第十周作业

两个数求平方和的方法

package aaa;

public class Homework {
     public static int sum(int a, int b) {
            return a * a + b * b;
        }

        public static void main(String[] args) {
            System.out.println(sum(2, 3));
        }
    }

 

 

1.编写一个方法，实现冒泡排序（由小到大），并调用该方法

package aaa;

import java.util.Scanner;

public class Homework1 {
     public static void mpf() {
            Scanner input = new Scanner(System.in);
            System.out.println("请输入5个数：");
            int x[] = new int[5];
            for (int i = 0; i < x.length; i++) {
                x[i] = input.nextInt();
            }
            for (int i = 0; i < x.length - 1; i++) {
                for (int j = 0; j < x.length - 1 - i; j++) {
                    if (x[j] > x[j + 1]) {
                        int temp = x[j];
                        x[j] = x[j + 1];
                        x[j + 1] = temp;
                    }
                }
            }
            System.out.println("排序后");
            for (int i = 0; i < x.length; i++) {
                System.out.println(x[i]);
            }
        }

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

 

 

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 aaa;

public class Homework1 {
    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) {
        System.out.println(jiecheng(5));
    }
}

 

 

3.编写一个方法，判断该年份是平年还是闰年。[必做题]

package aaa;

import java.util.Scanner;

public class Homework1 {
     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("该年份是闰年");
            } else {
                System.out.println("该年份是平年");
            }
        }

        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

package aaa;

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

public class Homework1 {
    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:
            draw();
            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 draw() {
        Scanner input = new Scanner(System.in);
        System.out.println("输入一个4位会员卡号");
        int number = input.nextInt();
        int baiwei = number / 100 % 10;
        Random r = new Random();
        int x = (int) r.nextInt(10);
        if (baiwei == x) {
            System.out.println("该用户是幸运会员");
        } else {
            System.out.println("该用户不是幸运会员");
        }
        returnMain();
    }

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