Java第十周作业

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 zxcz {
    
    public static void px() {
        Scanner input = new Scanner(System.in);
        System.out.println("输入5个数：");
        int a[] = new int[5];
        int b;
        for (int i = 0; i < a.length; i++) {
            a[i] = input.nextInt();
        }
        for (int i = 0; i < a.length - 1; i++) {
            for (int j = i+1; j < a.length; j++) {
                if (a[i] > a[j]) {
                    b = a[i];
                    a[i] = a[j];
                    a[j] = b;
                }
            }
        }
        for (int i = 0; i < a.length; i++) {
            System.out.print(a[i]);
            System.out.print("  ");
        }
        System.out.println();
    }
    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。 [必做题]

import java.util.Scanner;
public class zxcz {
    
    public static int jc(int a){
        int sum=1;
        for(int i=1;i<=a;i++){
            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。[必做题]

import java.util.Scanner;
public class zxcz {
    
    public static void pr() {
        Scanner input=new Scanner(System.in);
        int a=input.nextInt();
         if (a % 400 == 0 & a % 100 != 0 | a % 4 == 0)
             System.out.println("该年为闰年");
         else
             System.out.println("该年为平年");
     }
    public static void main(String[] args) {
        pr();
    }
}

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 zxcz {
    
    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("1")&&pwd.equals("1"))
            System.out.println("成功");
        else
            System.out.println("失败");
        returnMain();    

    }
    public static void draw(){
        Scanner input = new Scanner(System.in);
        Random r=new Random();
        int a=r.nextInt(10);
        System.out.println("输入四位会员卡号");
        int kahao=input.nextInt();
        int c=kahao%100/10;
        System.out.println("幸运数字为"+a);
        if(c==a){
            System.out.println("是幸运会员");
        }
        else{
            System.out.println("不是幸运会员");
        }
        returnMain();
    }

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

}