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What are Runtime.getRuntime().totalMemory() and freeMemory()?
...o includes comments and observations from others on the same question, and my own experience.
* <p>
* <img src="https://i.stack.imgur.com/GjuwM.png" alt="Runtime's memory interpretation">
* <p>
* <b>JVM memory management crash course</b>:
* Java virtual machine pro...
Appending an element to the end of a list in Scala
I can't add an element of type T into a list List[T] .
I tried with myList ::= myElement but it seems it creates a strange object and accessing to myList.last always returns the first element that was put inside the list. How can I solve this problem?
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What is the use for Task.FromResult in C#
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... and to answer my own question, the benefit of a cache of Tasks is that some of them can be completed tasks, and others can be ones that have not yet finished. Callers don't have to care: they do an asynchronous call, and if it is already c...
How do I create a parameterized SQL query? Why Should I?
...squip values(null,?,?)';
$statement=$dbh->prepare($sql);
$data=array('my user supplied data','more stuff');
$statement->execute($data);
if($statement->rowCount()==1){/*it worked*/}
This takes care of escaping your data for database insertion.
One advantage is that you can repeat an i...
Why is char[] preferred over String for passwords?
...orrect me if I am wrong).
Update
Thanks to the comments I have to update my answer. Apparently there are two cases where this can add a (very) minor security improvement as it reduces the time a password could land on the hard drive. Still I think it's overkill for most use cases.
Your target sy...
What's the difference between identifying and non-identifying relationships?
...reign key column allows NULL or disallows NULL, respectively.
See also my answer to Still Confused About Identifying vs. Non-Identifying Relationships
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Determine the type of an object?
...d and this can sometime lead to unexpected results. Mainly for this reason my favorite way of testing types/classes is to the isinstance built in function.
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Eager load polymorphic
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My guess is that your models look like this:
class User < ActiveRecord::Base
has_many :reviews
end
class Review < ActiveRecord::Base
belongs_to :user
belongs_to :reviewable, polymorphic: true
end
class Shop <...
Why do we need the “event” keyword while defining events?
...- it's an encapsulation disaster.
For more on events (and delegates) read my article on this topic. (At some point I need to update this for C# 4, which changes field-like events very slightly. The gist of it is still correct though.)
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Use email address as primary key?
... of inserts as they now have only one index to update instead of two.
In my humble opinion, it's not a slam-dunk either way. I tend to prefer to use natural keys when a practical one is available because they're just easier to work with, and the disadvantages tend to not really matter much in most...