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

package homework9;
import java.util.Scanner;
public class Test1 {

    public static void sx(){
           Scanner input=new Scanner(System.in);

        // TODO Auto-generated method stub
        System.out.println("请输入5位数组");
        int a[]=new int [5];
       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;j++){
                  if(a[j]>a[j+1]){
                  int temp=a[j];
                  a[j]=a[j+1];
                  a[j+1]=temp;
                  }
              }
          }
          for (int i : a) {
            System.out.println(i);
       }
         
          }
public static void main(String[] args){
    sx();

    }

}

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 homework9;

public class Test2 {

    public static int jc(int n){
        int sum=1;
        for(int i=1;i<=n;i++){
            sum=sum*i;
        }
        return sum;
      }

    public static void main(String[] args){
        System.out.println(jc(6));

    }

}

3.编写一个方法，判断该年份是平年还是闰年。[必做题]

package homework9;

public class Test3 {

     public static int pr(int n){
            if(n%4==0&&n%100!=0||n%400==0)
                System.out.println("是闰年");
            else
                System.out.println("是平年");
            return n;
          }

        public static void main(String[] args){
            System.out.println(pr(2020));

    }

}

4.课堂没完成的menu菜单，实现幸运抽奖功能

package homework9;
import java.util.Random;
import java.util.Scanner;

public class Test4 {

    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:
            xycj();
            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 xycj() {
        Scanner input = new Scanner(System.in);
        System.out.println("输入一个4位会员卡号");
        int number = input.nextInt();
        int bw = number / 100 % 10;
        Random r = new Random();
        int a = (int) r.nextInt(10);
        if (bw == a) {
            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();

    }

}