Don't get me wrong. During my professional life I have written tons of Java code and of course I think it is a great language still. For sure it has been a great improvement from C++ and Smalltalk. But now even Java is starting to feel the weight of its 15 years.
Indeed during my experience I had to face up with some mistakes, flaws and lacks in its design and specification that made my Java programmer life less pleasant. With millions of Java programmers and billions of lines of code out in the world, I am far to say that Java is going to be dead in the near future. Anyway after the rise of some JVM compatible languages (my favorite is Scala), these issues are becoming even less tolerable and I am starting thinking that it is time to slowly move away from Java (but not from the JVM). More in detail, in my opinion, the 10 most important problems of the Java language are:
1. Lack of closure: I don't think I have to explain this. Functional programming exists since decades, but in the last years they are gaining more and more interests, mostly because it allows to write naturally parallelizable programs. I partially agree with Joshua Bloch that underlined the problems of introducing them in Java as a second thought (the BGGA proposal was truly awful), but anyway their lack makes impossible to have any kind of real functional programming in Java.
2. Lack of first class function: this issue is in some way related to the former one but I believe it is even worse. The only way to achieve a similar result in Java is by using the ugly and sadly famous one-method anonymous inner classes, but it looks actually a poor solution. Even in C# has been provided a better one by the implementation of the delegate mechanism.
3. Primitive types: it should be beautiful if everything in Java was an Object, but they didn't design it in that way. That leaded to some issue, like the impossibility to have a Collection of int partially resolved in Java 5 through the autoboxing feature (see below). It also generated some confusion between passing by value and passing by reference. Indeed a primitive data type is passed to a method by value (a copy of the data type is duplicated, and passed to the function) while true objects are passed by reference.
4. Autoboxing and autounboxing: this feature has been introduced in Java 5 to overcome the problems caused by the presence of primitive types. It allows to silently convert a primitive type in the corresponding object, but often it is cause of other problems. For example an Integer can have null value, but the same doesn't apply to int, so in this case when the Integer is changed in an int the JVM can't do anything else than throw a difficult to debug NullPointerException. Moreover it is cause of other strange behavior like in the following example where it is not so easy to understand why the test variable is false:
Intger a = new Integer(1024);
Intger b = new Integer(1024);
boolean test = a < b || a == b || a > b;
5. Lack of generics reification: generics are one of the cool features introduced with Java 5, but in order to mantain the compatibility with the older version of java they miss some important characteristic. In particular it is not possible to introspect their generic type at runtime. For example if you have a method that accepts as parameter a List<?> and you pass to it a List<String> you are not allowed to know at runtime the actual type of the generic. For the same reason you cannot create array of generics. It means that despite it looks quite natural the following statement won't compile:
List<String>[] listsOfStrings = new List<String>[3];
6. Unavoidable generics warnings: have you ever found yourself in the impossibility to get rid of a bothering warning about generics? If you make a large use of generics like me, I bet you did. And the fact that they felt the need to introduce a special annotation to manage this situation (@SuppressWarnings("unchecked")) is symptomatic of the dimension of this problem and, in my opinion, that generics could have been designed better.
7. Impossibility to pass a void to a method invocation: I admit that the need to pass a void to a method could look weird at a first glance. Anyway I like DSL and while implementing a special feature of my DSL library (lambdaj) I had the need to have a method with a simple signature like this: void doSomething(Object parameter) where the parameter passed to this method is the result of another method invocation done with the only purpose to register the invocation itself and execute it in the future. With my big surprise, and apparently without a good reason, since the println method returns void, I am not allowed to write something like this:
doSomething(System.out.println("test"));
8. No native proxy mechanism: proxy is a very powerful and widely used pattern, but Java offers a mechanism to proxy only interfaces and not concrete classes. This is why a library that provide this feature like cglib is employed in so many main stream frameworks like Spring and Hibernate. Moreover cglib implements this feature by creating at runtime a Class that extends the proxied one, so this approach has a well known limitation in the impossibility to extend and then proxy a final Class like String.
9. Poor switch ... case statement: the switch ... case as specified in java allows to switch only on int and (starting from java 5) enum. That looks extremely few powerful especially if compared with what offered by a more modern language like Scala.
10. Checked exception: like primitive types, checked exception have been one of the original sins of Java. They oblige programmers to do one of the following two equally horrible things: fill your code with tons of poorly readable and error prone try ... catch statement where often the most meaningful thing to do is to wrap the catched exception in a runtime one and rethrow it; or blurring your API with lots of throws clause making them less flexible and extensible.
The real problem here is that the only way to fix the biggest part of the issues I mentioned is to take a painful decision and define a specification of the language that drops the backward compatibility with the current one. I guess they will never do that, even if I believe it should not be extremely difficult to write a program that allows to automatically translate the old Java sources in order to make them compatible with this new hypothetic release. And in the end, this is the reason why I decided to start looking for a better JVM compatible language.
分享到:
相关推荐
On one hand, scientists do not always have the time to learn another programming language, especially if they are making a PhD, or doing something else which asks for a lot of time. Using direct and ...
In some cases there might be good arguments for changing certain style rules, but we nonetheless keep things as they are in order to preserve consistency. Another issue this guide addresses is that...
On production servers, 4096 bytes is a good setting for performance ; reasons. ; Note: Output buffering can also be controlled via Output Buffering Control ; functions. ; Possible Values: ; On = ...
内容概要:本文档《数据结构》(02331)第一章主要介绍数据结构的基础概念,涵盖数据与数据元素的定义及其特性,详细阐述了数据结构的三大要素:逻辑结构、存储结构和数据运算。逻辑结构分为线性结构(如线性表、栈、队列)、树形结构(涉及根节点、父节点、子节点等术语)和其他结构。存储结构对比了顺序存储和链式存储的特点,包括访问方式、插入删除操作的时间复杂度以及空间分配方式,并介绍了索引存储和散列存储的概念。最后讲解了抽象数据类型(ADT)的定义及其组成部分,并探讨了算法分析中的时间复杂度计算方法。 适合人群:计算机相关专业学生或初学者,对数据结构有一定兴趣并希望系统学习其基础知识的人群。 使用场景及目标:①理解数据结构的基本概念,掌握逻辑结构和存储结构的区别与联系;②熟悉不同存储方式的特点及应用场景;③学会分析简单算法的时间复杂度,为后续深入学习打下坚实基础。 阅读建议:本章节内容较为理论化,建议结合实际案例进行理解,尤其是对于逻辑结构和存储结构的理解要深入到具体的应用场景中,同时可以尝试编写一些简单的程序来加深对抽象数据类型的认识。
内容概要:本文详细介绍了施耐德M580系列PLC的存储结构、系统硬件架构、上电写入程序及CPU冗余特性。在存储结构方面,涵盖拓扑寻址、Device DDT远程寻址以及寄存器寻址三种方式,详细解释了不同类型的寻址方法及其应用场景。系统硬件架构部分,阐述了最小系统的构建要素,包括CPU、机架和模块的选择与配置,并介绍了常见的系统拓扑结构,如简单的机架间拓扑和远程子站以太网菊花链等。上电写入程序环节,说明了通过USB和以太网两种接口进行程序下载的具体步骤,特别是针对初次下载时IP地址的设置方法。最后,CPU冗余部分重点描述了热备功能的实现机制,包括IP通讯地址配置和热备拓扑结构。 适合人群:从事工业自动化领域工作的技术人员,特别是对PLC编程及系统集成有一定了解的工程师。 使用场景及目标:①帮助工程师理解施耐德M580系列PLC的寻址机制,以便更好地进行模块配置和编程;②指导工程师完成最小系统的搭建,优化系统拓扑结构的设计;③提供详细的上电写入程序指南,确保程序下载顺利进行;④解释CPU冗余的实现方式,提高系统的稳定性和可靠性。 其他说明:文中还涉及一些特殊模块的功能介绍,如定时器事件和Modbus串口通讯模块,这些内容有助于用户深入了解M580系列PLC的高级应用。此外,附录部分提供了远程子站和热备冗余系统的实物图片,便于用户直观理解相关概念。
某型自动垂直提升仓储系统方案论证及关键零部件的设计.zip
2135D3F1EFA99CB590678658F575DB23.pdf#page=1&view=fitH
可以搜索文本内的内容,指定目录,指定文件格式,匹配大小写等
Windows 平台 Android Studio 下载与安装指南.zip
Android Studio Meerkat 2024.3.1 Patch 1(android-studio-2024.3.1.14-windows.zip)适用于Windows系统,文件使用360压缩软件分割成两个压缩包,必须一起下载使用: part1: https://download.csdn.net/download/weixin_43800734/90557033 part2: https://download.csdn.net/download/weixin_43800734/90557035
国网台区终端最新规范
国网台区终端最新规范
1.【锂电池剩余寿命预测】Transformer-GRU锂电池剩余寿命预测(Matlab完整源码和数据) 2.数据集:NASA数据集,已经处理好,B0005电池训练、B0006测试; 3.环境准备:Matlab2023b,可读性强; 4.模型描述:Transformer-GRU在各种各样的问题上表现非常出色,现在被广泛使用。 5.领域描述:近年来,随着锂离子电池的能量密度、功率密度逐渐提升,其安全性能与剩余使用寿命预测变得愈发重要。本代码实现了Transformer-GRU在该领域的应用。 6.作者介绍:机器学习之心,博客专家认证,机器学习领域创作者,2023博客之星TOP50,主做机器学习和深度学习时序、回归、分类、聚类和降维等程序设计和案例分析,文章底部有博主联系方式。从事Matlab、Python算法仿真工作8年,更多仿真源码、数据集定制私信。
Android项目原生java语言课程设计,包含LW+ppt
大学生入门前端-五子棋vue项目
这是一个完整的端到端解决方案,用于分析和预测阿联酋(UAE)地区的二手车价格。数据集包含 10,000 条二手车信息,覆盖了迪拜、阿布扎比和沙迦等城市,并提供了精确的地理位置数据。此外,项目还包括一个基于 Dash 构建的 Web 应用程序代码和一个训练好的 XGBoost 模型,帮助用户探索区域市场趋势、预测车价以及可视化地理空间洞察。 数据集内容 项目文件以压缩 ZIP 归档形式提供,包含以下内容: 数据文件: data/uae_used_cars_10k.csv:包含 10,000 条二手车记录的数据集,涵盖车辆品牌、型号、年份、里程数、发动机缸数、价格、变速箱类型、燃料类型、颜色、描述以及销售地点(如迪拜、阿布扎比、沙迦)。 模型文件: models/stacking_model.pkl:训练好的 XGBoost 模型,用于预测二手车价格。 models/scaler.pkl:用于数据预处理的缩放器。 models.py:模型相关功能的实现。 train_model.py:训练模型的脚本。 Web 应用程序文件: app.py:Dash 应用程序的主文件。 callback
资源内项目源码是来自个人的毕业设计,代码都测试ok,包含源码、数据集、可视化页面和部署说明,可产生核心指标曲线图、混淆矩阵、F1分数曲线、精确率-召回率曲线、验证集预测结果、标签分布图。都是运行成功后才上传资源,毕设答辩评审绝对信服的保底85分以上,放心下载使用,拿来就能用。包含源码、数据集、可视化页面和部署说明一站式服务,拿来就能用的绝对好资源!!! 项目备注 1、该资源内项目代码都经过测试运行成功,功能ok的情况下才上传的,请放心下载使用! 2、本项目适合计算机相关专业(如计科、人工智能、通信工程、自动化、电子信息等)的在校学生、老师或者企业员工下载学习,也适合小白学习进阶,当然也可作为毕设项目、课程设计、大作业、项目初期立项演示等。 3、如果基础还行,也可在此代码基础上进行修改,以实现其他功能,也可用于毕设、课设、作业等。 下载后请首先打开README.txt文件,仅供学习参考, 切勿用于商业用途。
资源内项目源码是来自个人的毕业设计,代码都测试ok,包含源码、数据集、可视化页面和部署说明,可产生核心指标曲线图、混淆矩阵、F1分数曲线、精确率-召回率曲线、验证集预测结果、标签分布图。都是运行成功后才上传资源,毕设答辩评审绝对信服的保底85分以上,放心下载使用,拿来就能用。包含源码、数据集、可视化页面和部署说明一站式服务,拿来就能用的绝对好资源!!! 项目备注 1、该资源内项目代码都经过测试运行成功,功能ok的情况下才上传的,请放心下载使用! 2、本项目适合计算机相关专业(如计科、人工智能、通信工程、自动化、电子信息等)的在校学生、老师或者企业员工下载学习,也适合小白学习进阶,当然也可作为毕设项目、课程设计、大作业、项目初期立项演示等。 3、如果基础还行,也可在此代码基础上进行修改,以实现其他功能,也可用于毕设、课设、作业等。 下载后请首先打开README.txt文件,仅供学习参考, 切勿用于商业用途。
此为代码审查工具 可查 文件数,字节数,总行数,代码行数,注释行数,空白行数,注释率等
内容概要:本文档涵盖了一项关于企业破产概率的详细分析任务,分为书面回答和Python代码实现两大部分。第一部分涉及对业务类型和破产状态的边际分布、条件分布及相对风险的计算,并绘制了相应的二维条形图。第二部分利用Python进行了数据处理和可视化,包括计算比值比、识别抽样技术类型、分析鱼类数据集以及探讨辛普森悖论。此外,还提供了针对鱼类和树木数据的统计分析方法。 适合人群:适用于有一定数学和编程基础的学习者,尤其是对统计学、数据分析感兴趣的大学生或研究人员。 使用场景及目标:①帮助学生掌握统计学概念如边际分布、条件分布、相对风险和比值比的实际应用;②教授如何用Python进行数据清洗、分析和可视化;③提高对不同类型抽样技术和潜在偏见的理解。 其他说明:文档不仅包含了理论知识讲解,还有具体的代码实例供读者参考实践。同时提醒读者在完成作业时需要注意提交格式的要求。