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微博为什么限制140字(附短信70字限制考) - 闲聊区 - 清泛IT社区，为创新赋能！
...满足，只好自己来考据一番。twitter说We like to keep it short and sweet! It also just so happens that 140 characters is the perfect length for sending status updates via text message. The standard text message length in most places is 160 characters per message. We reserve 20 characters ...
What is the difference between the HashMap and Map objects in Java?
...(in another question, people answered using them seemingly interchangeably and I'm wondering if/how they are different):
13...
getActivity() returns null in Fragment function
... suggest adding an
onAttach(Activity activity)
method to your Fragment and putting a break point on it and seeing when it is called relative to your call to asd(). You'll see that it is called after the method where you make the call to asd() exits. The onAttach call is where the Fragment is att...
列表显示框布局：使用布局和元素字串 · App Inventor 2 中文网
...tailText
RecyclerView 实现说明
Android 版本的 列表显示框 使用 RecyclerView 渲染行项目。列表数据由统一的数据模型管理，界面刷新、搜索过滤和选中状态不会再各自维护一份副本，因此在增删项目或快速...
List passed by ref - help me explain this behaviour
...e value of the variable (i.e. the reference - think "pointer") is copied - and changes to the value of the parameter inside ChangeList aren't seen by TestMethod.
try:
private void ChangeList(ref List<int> myList) {...}
...
ChangeList(ref myList);
This then passes a reference to the local-v...
Can you explain the concept of streams?
I understand that a stream is a representation of a sequence of bytes. Each stream provides means for reading and writing bytes to its given backing store. But what is the point of the stream? Why isn't the backing store itself what we interact with?
...
When to call activity context OR application context?
...plicationContext() when you know why you are using getApplicationContext() and only when you need to use getApplicationContext().
To be blunt, "some programmers" use getApplicationContext() (or getBaseContext(), to a lesser extent) because their Java experience is limited. They implement an inner c...
“Least Astonishment” and the Mutable Default Argument
...
Actually, this is not a design flaw, and it is not because of internals, or performance.
It comes simply from the fact that functions in Python are first-class objects, and not only a piece of code.
As soon as you get to think into this way, then it completely ...
List files ONLY in the current directory
...
Just use os.listdir and os.path.isfile instead of os.walk.
Example:
import os
files = [f for f in os.listdir('.') if os.path.isfile(f)]
for f in files:
# do something
But be careful while applying this to other directory, like
files ...
How to implement an STL-style iterator and avoid common pitfalls?
I made a collection for which I want to provide an STL-style, random-access iterator. I was searching around for an example implementation of an iterator but I didn't find any. I know about the need for const overloads of [] and * operators. What are the requirements for an iterator to be "STL-s...