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HashMap get/put complexity
...tant time... but you could have a hash which takes a long time to compute, and if there are multiple items in the hash map which return the same hash code, get will have to iterate over them calling equals on each of them to find a match.
In the worst case, a HashMap has an O(n) lookup due to walki...
Using Build Flavors - Structuring source folders and build.gradle correctly
...ok at my IO talk you'll see how we mix in together values from the flavors and build type to create the variant.
For the Java source:
src/main/java
src/flavor1/java
src/debug/java
are all 3 used to create a single output. This means they can't define the same class.
If you want to have a differ...
How to escape text for regular expression in Java
...se not that this doesn’t escape the string itself, but wraps it using \Q and \E. This may lead to unexpected results, for example Pattern.quote("*.wav").replaceAll("*",".*") will result in \Q.*.wav\E and not .*\.wav, as you might expect.
– Matthias Ronge
Jan ...
What is the use of the ArraySegment class?
...
ArraySegment<T> has become a lot more useful in .NET 4.5+ and .NET Core as it now implements:
IList<T>
ICollection<T>
IEnumerable<T>
IEnumerable
IReadOnlyList<T>
IReadOnlyCollection<T>
as opposed to the .NET 4 version which implemented no interfaces...
Provide an image for WhatsApp link sharing
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2020 standards
It takes a few steps to get the perfect preview for WhatsApp, Twitter, Facebook and bookmark icons for pc's and mobile devices. If you like reading go to ogp.me - but make sure to read steps 1 - 6 in this answer to ge...
What is std::promise?
I'm fairly familiar with C++11's std::thread , std::async and std::future components (e.g. see this answer ), which are straight-forward.
...
How do I perform the SQL Join equivalent in MongoDB?
...t array field>
}
}
Of course Mongo is not a relational database, and the devs are being careful to recommend specific use cases for $lookup, but at least as of 3.2 doing join is now possible with MongoDB.
share
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“INSERT IGNORE” vs “INSERT … ON DUPLICATE KEY UPDATE”
...y.
Side effects are propagated to replicas too.
correction: both REPLACE and INSERT...ON DUPLICATE KEY UPDATE are non-standard, proprietary inventions specific to MySQL. ANSI SQL 2003 defines a MERGE statement that can solve the same need (and more), but MySQL does not support the MERGE statemen...
What are the most common SQL anti-patterns? [closed]
...d (or are learning) that SQL is different. Eliciting the desired results, and doing so efficiently, involves a tedious process partly characterized by learning unfamiliar paradigms, and finding out that some of our most familiar programming patterns don't work here. What are the common antipattern...
iPhone SDK: what is the difference between loadView and viewDidLoad?
When working with views and view controllers in an iPhone app, can anyone explain the difference between loadView and viewDidLoad?
...