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Getting a better understanding of callback functions in JavaScript
I understand passing in a function to another function as a callback and having it execute, but I'm not understanding the best implementation to do that. I'm looking for a very basic example, like this:
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How to hash some string with sha256 in Java?
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SHA-256 isn't an "encoding" - it's a one-way hash.
You'd basically convert the string into bytes (e.g. using text.getBytes(StandardCharsets.UTF_8)) and then hash the bytes. Note that the result of the hash would also be arbitrary binary data, and if you want to represent that in a strin...
How to convert currentTimeMillis to a date in Java?
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Calendar objects are generally considered quite large, so should be avoided when possible. A Date object is going to be better assuming it has the functionality you need. "Date date=new Date(millis);" provided in the other answer by user AVD is going ...
Python memory usage of numpy arrays
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The field nbytes will give you the size in bytes of all the elements of the array in a numpy.array:
size_in_bytes = my_numpy_array.nbytes
Notice that this does not measures "non-element attributes of the array object" so the actual size in bytes can be a few bytes larger th...
Unittest setUp/tearDown for several tests
...ably going to be to create your own derived TestSuite and override run(). All other calls would be handled by the parent, and run would call your setup and teardown code around a call up to the parent's run method.
share
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Rails check if yield :area is defined in content_for
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not really necessary to create a helper method:
<% if @content_for_sidebar %>
<div id="sidebar">
<%= yield :sidebar %>
</div>
<% end %>
then of course in your view:
<% content_for :sideb...
Primary key or Unique index?
...ork we have a big database with unique indexes instead of primary keys and all works fine.
15 Answers
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Using Java 8's Optional with Stream::flatMap
...latMap(Optional::stream)
.findFirst();
Java 8
Yes, this was a small hole in the API, in that it's somewhat inconvenient to turn an Optional<T> into a zero-or-one length Stream<T>. You could do this:
Optional<Other> result =
things.stream()
.map(this::resolv...
How to get the connection String from a database
... This works perfectly and doesn't require the connection to be setup in VS.
– Robino
Jun 1 '16 at 15:47
Haha, this ...
How to list variables declared in script in bash?
... I have to make something to save them to file.
My question is how to list all variables declared in my script and get list like this:
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