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System.currentTimeMillis() vs. new Date() vs. Calendar.getInstance().getTime()
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System.currentTimeMillis() is obviously the most efficient since it does not even create an object, but new Date() is really just a thin wrapper about a long, so it is not far behind. Calendar, on the other hand, is relatively slow and very comple...
CHECK constraint in MySQL is not working
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MySQL 8.0.16 is the first version that supports CHECK constraints.
Read https://dev.mysql.com/doc/refman/8.0/en/create-table-check-constraints.html
If you use MySQL 8.0.15 or earlier, the MySQL Reference Manual says:
The CHECK clau...
What does the “>” (greater-than sign) CSS selector mean?
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> is the child combinator, sometimes mistakenly called the direct descendant combinator.1
That means the selector div > p.some_class only selects paragraphs of .some_class that are nested directly inside a div, and not any p...
Transposing a 2D-array in JavaScript
... an array, in order, and constructs a new array from the results. callback is invoked only for indexes of the array which have assigned values; it is not invoked for indexes which have been deleted or which have never been assigned values.
callback is invoked with three arguments: the value of ...
HTTP Error 503. The service is unavailable. App pool stops on accessing website
There are number of posts on this and I have tried many a things by now. But to no avail. Myself a Winforms Developer basically, started working on this Web stuff few days back as my company is taking Web initiatives.
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Why is super.super.method(); not allowed in Java?
I read this question and thought that would easily be solved (not that it isn't solvable without) if one could write:
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Is there anything like .NET's NotImplementedException in Java?
Is there anything like .NET's NotImplementedException in Java?
5 Answers
5
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How to profile a bash shell script slow startup?
...f you have GNU date (or another version that can output nanoseconds), do this at the beginning of /etc/bash.bashrc (or wherever you'd like to begin a trace in any Bash script):
PS4='+ $(date "+%s.%N")\011 '
exec 3>&2 2>/tmp/bashstart.$$.log
set -x
add
set +x
exec 2>&3 3>&...
Why doesn't java.lang.Number implement Comparable? [duplicate]
...oes anyone know why java.lang.Number does not implement Comparable ? This means that you cannot sort Number s with Collections.sort which seems to me a little strange.
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Iterator invalidation rules
...nsert, emplace_back, emplace, push_back cause reallocation if the new size is greater than the old capacity. Reallocation invalidates all the references, pointers, and iterators referring to the elements in the sequence. If no reallocation
happens, all the iterators and references before the inserti...