第十周Java作业

 

 

求平方和

 1 import java.util.Scanner;
 2 
 3 public class wn1  {
 4     public static void square(double a, int b) {
 5         int sum = (int) (a * a + b * b);
 6         System.out.print("输出平方和");
 7         System.out.print(sum);
 8 
 9     }
10 
11     public static void main(String[] args) {
12         square(1.5, 3);
13     }
14 }

　　

 

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 wn2 {
    public static void n(int a[]) {
        for (int i = 0; i < a.length; i++) {
            for (int j =i+1; j < a.length; j++) {
                if (a[i]>a[j]) {
                    int temp=a[i];
                    a[i]=a[j];
                    a[j]=temp;
                }
            }
        }
    }    
    public static void main(String[] args) {
     int a[]=new int[5];
     Scanner b=new Scanner(System.in);
     for (int i = 0; i < a.length; i++) {
        System.out.println("请输入第"+(i+1)+"个整数");
        a[i]=b.nextInt();
    }
     System.out.println("排序前：");
     for (int i = 0; i < a.length; i++) {
         System.out.print(a[i]+" ");
    }
     n(a);
     System.out.println();
     System.out.println("排序后：");
     for (int i = 0; i < a.length; i++) {
        System.out.print(a[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]

 1 import java.util.Scanner; 
 3 public class wn3 {
 4     public static int jc(int n) {
 5         int sum = 1;
 6         for (int i = 1; i <= n; i++) {
 7             sum *= i;
 8         }
 9         System.out.println("阶乘:");
10         return sum;
11     }
12 
13     public static void main(String[] args) {
14         System.out.println(jc(5));
15     }
16 }

　

 

 

　

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 wn4{

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

    private static void year() {
        Scanner input=new Scanner(System.in);
        System.out.println("输入年份");
        int a=input.nextInt();
        if (a % 4==0 && a % 100!= 0||a % 400 == 0 ) {
        System.out.println("是闰年");
        } 
        else {
                System.out.println("不是闰年");
        }
        
    }
    

}

　　

 

 

4.课堂没完成的menu菜单，实现幸运抽奖功能

 

 

import java.util.Scanner;

public class wn5 {

    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:
            hy();
            break;
        }
    }
    //完成3 输入四位会员卡号 如果百位等于随机数，就是幸运会员。询问是否返回主菜单。
    public static void hy(){
        Scanner input = new Scanner(System.in);    
        System.out.println("请输入四位数卡号:");
        int a=input.nextInt();
            int random = (int) (Math.random() * 10);
        if (random == a / 100 % 10){
           System.out.println("幸运会员");
                                                     
        }
        else{
            System.out.println("不是");
            returnMain();
        }
    }
    
        
    
    
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 main(String[] args) {
        mainMenu();
    }

}