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Polymorphism: Why use “List list = new ArrayList” instead of “ArrayList list = new ArrayList”? [dupl
...uple your code from a specific implementation of the interface. When you write your code like this:
List list = new ArrayList();
the rest of your code only knows that data is of type List, which is preferable because it allows you to switch between different implementations of the List interfac...
Import Maven dependencies in IntelliJ IDEA
...estion about IntelliJ IDEA 11. I just imported a project from subversion - its a maven project. But I have a problem in maven library dependencies so that I can't include all maven dependencies automatically - IDEA shows dependency errors only when I open that class/ Thats what I get here:
...
What does the ??!??! operator do in C?
...
??! is a trigraph that translates to |. So it says:
!ErrorHasOccured() || HandleError();
which, due to short circuiting, is equivalent to:
if (ErrorHasOccured())
HandleError();
Guru of the Week (deals with C++ but relevant here), where I picked this up.
Pos...
Clang vs GCC - which produces faster binaries? [closed]
...m currently using GCC, but I discovered Clang recently and I'm pondering switching. There is one deciding factor though - quality (speed, memory footprint, reliability) of binaries it produces - if gcc -O3 can produce a binary that runs 1% faster, or Clang binaries take up more memory or just fail ...
what's data-reactid attribute in html?
...d attribute is a custom attribute used so that React can uniquely identify its components within the DOM.
This is important because React applications can be rendered at the server as well as the client. Internally React builds up a representation of references to the DOM nodes that make up your ap...
How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
...ey) DO UPDATE (and ON CONFLICT (key) DO NOTHING), i.e. upsert.
Comparison with ON DUPLICATE KEY UPDATE.
Quick explanation.
For usage see the manual - specifically the conflict_action clause in the syntax diagram, and the explanatory text.
Unlike the solutions for 9.4 and older that are given below, ...
How to add directory to classpath in an application run profile in IntelliJ IDEA?
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In Intellij 13, it looks it's slightly different again. Here are the instructions for Intellij 13:
click on the Project view or unhide it by clicking on the "1: Project" button on the left border of the window or by pressing Alt + 1
find y...
How to show the “Are you sure you want to navigate away from this page?” when changes committed?
...17)
Modern browsers now consider displaying a custom message to be a security hazard and it has therefore been removed from all of them. Browsers now only display generic messages. Since we no longer have to worry about setting the message, it is as simple as:
// Enable navigation prompt
window.on...
Releasing memory in Python
...arena will not be released. In Python 3.3 the small object allocator was switched to using anonymous memory maps instead of the heap, so it should perform better at releasing memory.
Additionally, the built-in types maintain freelists of previously allocated objects that may or may not use the smal...
How to overcome root domain CNAME restrictions?
...ains to refer to those applications, usually they want that any user that either type http://www.customer1.example or http://customer1.example goes to their web application.
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