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When do I need to use AtomicBoolean in Java?
...e. You can fix it by using AtomicBoolean:
if (atomicInitialized.compareAndSet(false, true)) {
initialize();
}
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Do C# Timers elapse on a separate thread?
...stem.Timers.Timer has two modes of operation.
If SynchronizingObject is set to an ISynchronizeInvoke instance then the Elapsed event will execute on the thread hosting the synchronizing object. Usually these ISynchronizeInvoke instances are none other than plain old Control and Form instances th...
Include intermediary (through model) in responses in Django Rest Framework
...fine a field on it like:
groups = MembershipSerializer(source='membership_set', many=True)
and then on your membership serializer you can create this:
class MembershipSerializer(serializers.HyperlinkedModelSerializer):
id = serializers.Field(source='group.id')
name = serializers.Field(s...
what does the __file__ variable mean/do?
...
When a module is loaded from a file in Python, __file__ is set to its path. You can then use that with other functions to find the directory that the file is located in.
Taking your examples one at a time:
A = os.path.join(os.path.dirname(__file__), '..')
# A is the parent director...
Which comment style should I use in batch files?
...ht. For instance, %VAR% variables are expanded. Suppose you have (wrongly) set TARGET=C:\Program Files (x86)\"foo.exe", and inside a DO(..) expression you have :: echo %TARGET% you will get an error because the (x86) gets expanded before the whole expression gets evaluated, leading to an invalid DO(...
Which is generally best to use — StringComparison.OrdinalIgnoreCase or StringComparison.InvariantCul
...tring comparison, casing, and sorting should strongly consider using a new set of String overloads in Microsoft .NET 2.0. Specifically, data that is designed to be culture-agnostic and linguistically irrelevant should begin specifying overloads using either the StringComparison.Ordinal or StringComp...
Access Enum value using EL with JSTL
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You can add each of the enum values you use into the page context:
<c:set var="VALID" value="<%=Status.VALID%>"/>
and then you can do this:
<c:when test="${dp.status == VALID}">
I prefer the last option (3), even though it also uses a scriptlet. This is because it only uses i...
How does cookie “Secure” flag work?
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The client sets this only for encrypted connections and this is defined in RFC 6265:
The Secure attribute limits the scope of the cookie to "secure" channels (where "secure" is defined by the user agent). When a cookie has the Sec...
How can I suppress column header output for a single SQL statement?
... 1 | pete |
| 2 | john |
| 3 | mike |
+------+-------+
3 rows in set (0.00 sec)
Credit to ErichBSchulz for pointing out the -N alias.
To remove the grid (the vertical and horizontal lines) around the results use -s (--silent). Columns are separated with a TAB character.
mysql -s ...
us...
In Firebase, is there a way to get the number of children of a node without loading all the node dat
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The code snippet you gave does indeed load the entire set of data and then counts it client-side, which can be very slow for large amounts of data.
Firebase doesn't currently have a way to count children without loading data, but we do plan to add it.
For now, one solution wou...