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 qqq;

public class qq {
    public static void main(int x[] ) {
//      1.编写一个方法，实现冒泡排序（由小到大），并调用该方法
      int a = 0;
      for (int i = x.length - 1; i > 0; i--) {
          for (int j = 0; j < i; j++) {
              if (x[j] > x[i]) {
                  a = x[j];
                  x[j] = x[i];
                  x[i] = a;
              }

          }

      }

  }

  public static void main(String[] args) {
      int x[] = { 9, 5, 7, 2, 3, 1, 10 };
      main(x);
      for (int i : x) {
          System.out.print(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 qqq;

import java.util.Scanner;

public class ee {
    public static int x (int a ) {
        int sum=1;
        for (int i = 1; i <= a; i++) {
            sum*=i;
        }
        return sum;
    }


public static void main(String[] args) {
//    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]
    System.out.println("输入一个数");
Scanner input = new Scanner(System.in);
int x = x(input.nextInt());
System.out.println(x);
}
}

3.编写一个方法，判断该年份是平年还是闰年。[必做题]

package qqq;

import java.util.Scanner;

public class ww {
     public static int year() {
            System.out.println("输入年份");
            Scanner input = new Scanner(System.in);
            int x = input.nextInt();
            if (x % 4 == 0 && x % 100!=0 || x % 400 == 0) {
                System.out.println("该年为闰年");
            }else {
                System.out.println("该年为平年");
            }
            return x;
        }
        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 qqq;
import java.util.Random;
import java.util.Scanner;
public class rr {
    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:
            lucky();
        }
    }
    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 lucky() {
        Random r = new Random();
        Scanner input = new Scanner(System.in);
        int luck = r.nextInt(10);
        System.out.println("输入一个4位数会员卡号");
        int id= input.nextInt();
        if (id%10/10 == luck) {
            System.out.println(id+"是幸运会员" );
        } 
        else {
            System.out.println(id+"不是幸运会员");
        }
            
        returnMain();
    }

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

    }