java中判断空字符串和null的判断⽅法简单总结⼏个⽅法：1.直观的：if(s == null ||"".equals(s));    //先判断是否对象，再判断是否是空字符串字符串长度判断2.⽐较字符串长度, 效率⾼, ⽐较绕:if(s == null || s.length() <= 0);3.效率和⽅法三⼏乎相等, 但出于兼容性考虑，不建议此⽅法.if(s ==...

Freemarker与Velocity1Freemarker字符串长度web1.1Freemarker简介FreeMarker是一个用Java语言编写的模板引擎，它基于模板来生成文本输出，仅是利用模板加上数据生成文本页面，即是由Java程序准备要显示的数据，由FreeMarker生成页面，通过模板显示准备的数据，并可以在模板中使用JSP标签。FreeMarker与Web容器无关，即在web运行时，...

string中的null和“”String str = null ; 表⽰声明⼀个字符串对象的引⽤，但指向为null，也就是说还没有指向任何的内存空间；String str = "";    表⽰声明⼀个字符串类型的引⽤，其值为""空字符串，这个str引⽤指向的是空字符串的内存空间；在java中变量和引⽤变量是存在栈中（stack），⽽对象（new产⽣的）都是存放在堆中（hea...

c 字符串哈希算法在C语言中，可以使用各种哈希算法来计算字符串的哈希值。下面是一个简单的示例，使用MD5哈希算法计算字符串的哈希值：```cinclude <stdio.h>include <string.h>include <openssl/md5.h>int main() {    const char* str = "Hello, wo...

java中string与json互相转化在Java中socket数据传输时，数据类型往往⽐較难选择。可能要考虑带宽、跨语⾔、版本号的兼容等问题。⽐較常见的做法有两种：⼀是把对象包装成JSON字符串传输，⼆是採⽤java对象的序列化和反序列化。随着Google⼯具protoBuf的开源。protobuf也是个不错的选择。对JSON,Object Serialize,ProtoBuf 做个对照。1、s...

2021年山东省济宁市全国计算机等级考试数据库技术模拟考试(含答案)学校:________ 班级:________ 姓名:________ 考号:________一、1.选择题(10题)1. 下列对进程间相互通信的描述错误的是A.进程互斥是指每次只允许一个进程使用临界资源 B.进程控制是通过原语实现的 C.P、V操作是一种进程同步机制 D.管道不是一种进程高级通信机制...

thinkphp实现redis简单的消息队列thinkphp 实现redis简单的消息队列本章简单的实现。消息队列的⼊列和出列1.⼊列，⼊列作为⽣产者，只管尽情的成产即可，⽆需考虑其他（秒杀、抢购场景除外）。此次我们假如有⼗个⽤户进⼊队列。//⼊列，⽣产者public function into(){$redis  = new Redis();//业务场景不在此阐述for ( $i =...

for循环和while循环的区别for循环和while循环的区别  使⽤区别：如果你想在循环结束后，继续使⽤控制条件的那个变量，⽤while循环，      　否则⽤for循环。不知道⽤for循环。      　因为变量及早的从内存中消失，可以提⾼内存的使⽤效率。  其实还有⼀种场景的理解:   ...

关于除夕的英语介绍作文11篇关于除夕的英语介绍作文（11篇）除夕这天，大家都不可以睡懒觉。起床之后都要穿好新衣服，然后全部聚到爷爷奶奶家一起过节。下面是小编给大家带来的关于除夕的英语介绍作文，欢迎大家阅读转发!关于除夕的英语介绍作文篇1That day,we have a very early dinner,got up to the street view of night.Wow!The st...

架构师面试题参考    架构师面试题参考     一、牛人出的面试题如下：     1. struts,spring,hibernate这样的开源框架，他们的历史局限性在哪里?在何种状况下会不适合用这些框架?     2. 假如要设计一个搜寻引擎，像google那样只有两个页面，要求性能最大化，web方面应当如何设计?...

简明创新方法一体化习题库和答案（精心整理）简明创新方法习题库一、单选题1．由“鸟”想到“飞机”，你认为是使用了哪类创新方法。AA．联想类创新方法B.组合类创新方法C.臻美类创新方法D.TRIZ创新方法解析：由一事物、思想观念想到另一事物、思想观念的心里过程，即由此即彼的想象为联想类创新方法。组合类创新方法的特点是以组合为核心，把表面看来似乎不相关的事物有机结合起来，合多而一。臻美类创新方法，是以”...

自动化控制系统目录1 概述根据XXX城市总体规划，通过对污水量的预测，并结合城市发展前景，确定污水处理厂建设规模为：设计规模2万m3/d。根据污水量和投资状况，我方在进行系统组态时，将全厂作为一个整体来考虑，并可方便地扩展或升级。系统选用符合国际标准的产品，其技术先进、结构开放，能够长期提供技术支持、备品备件有保障。同时，还充分考虑经济适用性、节省投资和与远期工程的衔接，与远期公用的控制子站，控制...

FDA发布咀嚼片关键质量属性指导原则（中英文对照）I. INTRODUCTIONII引言This guidance provides manufacturers of chewable tablets for human use with the Center for Drug Evaluation and Research,s (CDER) current thinking on the cri...

使用技术的同时要考虑污染问题英语作文结尾全文共6篇示例，供读者参考篇1    As I've learned about the amazing advances in technology and all the incredible things we can do with computers, robots, and other modern inventions, I...

如何使用电子产品的英语作文初二    In today's digital age, electronic products have become an integral part of our daily lives, especially for students in junior high. From smartphones and tablets to laptop...

mytimetable的作文    英文回答：    In today's fast-paced world, staying organized and managing time effectively is crucial to achieving success in various aspects of life. Creating a compr...

打兵乓球的准备事项英语作文Preparing for a game of table tennis requires some important steps to ensure that you are ready to play at your best. Here are some key things to consider when getting ready to play table...

乒乓球指导英语作文    英文回答：    Table Tennis Coaching.    Table tennis, also known as ping-pong, is a popular sport that can be enjoyed by people of all ages and skill levels. It i...

电脑上打英语作文打字English:When typing an English essay on the computer, it is important to pay attention to several key elements. First, make sure to use proper grammar, spelling, and punctuation. Utilize the...

英语普通词汇与高级词汇对照表According to me / I thinkI believeIn my personal sense, for my part /to my mind/ to the best knowledge of me/as far as I am concerned/in my opinion我认为 stopHinder/cease停止age   e...

will do与be going to do的用法差别 请看一道题：—I’ve come out without any money. —Never mind I __________ you some. A. am going to lend    B. will lend    C. have lent    D. am t...

辨析in和out of所组成的短语耀华程岗in和out of之后可以接同样的名词，但很多时候意思却是截然相反的，下面就以表格的形式加以展现：in (good) order 按照次序的 in (good) reason有很好理由的 out-of-order adj.无序的, 原次序被打乱了的 out of reason adj. 无理的 in benefit 有资格得到救济金(指生病、失业等津贴)...

必修④　Unit 1　Women of achievement过基础 晨读晚练——先识记再仿写·及时巩固(一)分类识记单词——用时少·功效高识记单词写对Ⅰ.知其意默想下面单词的词性和意义，不会的做出标记并核对识记□1.welfare          □2.project□3.institute       ...

1、这山望着那山高 The grass is always greener on the other hill。人都是这山望着那山高，对自己的状况没有满意的时候。Almost all people see that the grass is greener on the other hill. They never feel satisfied with what they’ve already...

THE CHARCOAL-BURNER AND THE FULLER烧炭工和漂洗工THERE was once a Charcoal-burner who lived and worked by himself. A Fuller, however, happened to come and settle in the same neighbourhood ; and the Charcoal-b...

          主讲：朱明 高级工程师、高级技师、国家经济师     高级国家职业技能鉴定考评员      高级技能专业教师综合英语3Unit5练习1.Vocabulary：  Choose the best answer for each of the following it...

2022年二级公共英语考试练习题及答案2022年二级公共英语考试练习题及答案阅读以下短文，回答{TSE}题目.Most people have had a dog or wanted one as their companion at some time in their lives.If you are thinking of buying a dog，however，you should fi...

  Ⅰ.根据首字母及英文释义写出单词1．purpose　thing that one intends to do, get, be, etc.2．offering  thing offered, esp.as a gift or contribution3．happiness  state of well­being characterized by emotion...

1.given可做介词,后跟宾语(不跟副词、副词短语,但可跟从句,这时可看作连词),引起条件状语,意为“考虑到……”。Given the general state of his health， it may take him a while to recover from the operation. Given her interest in children(=Given that she...

土石方工程劳动力、机械设备计划    英文回答：    The labor and machinery planning for earthwork projects is crucial for ensuring the smooth execution of the project and meeting the project timeline. Th...