关于c#:

I hate that there is no keyword to specify which exceptions are thrown from a method like in java. Its a much better way to document exceptions than using an XML comment. I would also want a much better syntax for generic constraints like oring and anding of constraints. Why a method can't return more than one value? Lack of support for aspect oriented programming in the language. Why can't you annotate each one of the property accessors with an attribute? Lack of builtin regexp support like in perl.

我知道我迟到了，但恨是永恒的!

Java

Runtime.exec(). So, if I don't manually clear the STDOUT and STDERR buffers, my code will hang? Wow. Die, plz. Null Pointer Exceptions. Responsible programming means I have to treat most objects like they're unexploded bombs, which is kind of a pisser in an object-oriented language. And when the inevitable happens I kinda need to know which object blew up in my face, but Java apparently feels telling me would be cheating. File I/O. Why do I have to jump through this many hoops to read a dang text file? And when copying files, I have to funnel the source file into my code and manually handle the output byte buffer? You're serious? Primitives vs. Primitive Wrappers. Note that Java now has a number of features that allow you to treat primitives and their wrapper objects as interchangeable in some places, but not in others; don't worry, the compiler will let you know which is which. This feels like a hack to work around a fundamentally broketastic design decision. And it is. (EDIT: Actually, the compiler is a much crappier safety net than I thought, particular when doing equality checks. If `a` and `b` are integers, `a == b` is guaranteed to behave as expected only if at least one of them is of type `int`. If they're both type `Integer`, then that statement will do what you think only if the two numbers are between -128 and 127. `Integer a = 1000; Integer b = 1000; return a == b;` will return `false`. Really.) XML. I have this dirt-simple little XML file I need to create and I have to do what?

Objective-C / Cocoa / Cocoa Touch:

Lack of namespaces Difficulty using primitive values with any of the interesting and powerful techniques of Cocoa, e.g., distributed objects, notifications, KVO Inconsistency with the use of the shortcut dot syntax for accessing properties, often having to use the full length accessors No GC on the iPhone, and generally GC came rather late to an otherwise highly dynamic language Inconsistent library support, at least in Cocoa Touch; some very basic things have only recently gotten high level support, e.g., audio handling. Lack of blocks!

C++

The inconsistencies in the libraries related to char* and std::string. All C++ libs should take std::strings. Characters are not bytes with respect to iostream. I do a lot of byte-oriented work. Having a "byte" type and a "character" type would significantly make it simpler. That, too, would permit scaling to Unicode somewhat easier. Bit operations should be easy on a value. I should be able to access and set the n'th bit of a value without playing AND/OR dancing. The lack of a standardized interface for GUIs. This is where Microsoft has really been able to position themselves well with C#. A standard interface binding that OS makers provide would go really far for my work.

C#

泛型参数是不变的，c# 4.0为泛型类型引入了协方差和逆变性 可覆盖的类成员必须显式地标记为virtual

Java

缺少无符号数字数据类型 基本数据类型不是对象

Python:

速度 静态分析(缺乏) 匿名函数仅限于一个表达式