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String concatenation: concat() vs “+” operator
...then throwing it away when you create the final String. In practice memory allocation is surprisingly fast.
Update: As Pawel Adamski notes, performance has changed in more recent HotSpot. javac still produces exactly the same code, but the bytecode compiler cheats. Simple testing entirely fails bec...
Using HeapDumpOnOutOfMemoryError parameter for heap dump for JBoss
...mentation has to say:
By default the heap dump is created in
a file called java_pid.hprof in the
working directory of the VM, as in the
example above. You can specify an
alternative file name or directory
with the -XX:HeapDumpPath= option. For
example -XX:HeapDumpPath=/disk2/dumps
...
How to obtain the number of CPUs/cores in Linux from the command line?
... Note that both of these will end up counting twice as many cores as actually exist if you're on a system with hyperthreading (e.g, P4, or Core i7).
– duskwuff -inactive-
Jun 26 '11 at 0:04
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Why are Perl 5's function prototypes bad?
...nd to expect prototypes to provide a mechanism for checking that function calls are correct: that is, that they have the right number and type of arguments. Perl's prototypes are not well-suited for this task. It's the misuse that's bad. Perl's prototypes have a singular and very different purpose:
...
Caveats of select/poll vs. epoll reactors in Twisted
...ePoll is a natural replacement for Select and Poll based networking, especially with Twisted. Which makes me paranoid, its pretty rare for a better technique or methodology not to come with a price.
...
Converting Long to Date in Java returns 1970
...ime.Instant // Represent a moment as seen in UTC. Internally, a count of nanoseconds since 1970-01-01T00:00Z.
.ofEpochSecond( 1_220_227_200L ) // Pass a count of whole seconds since the same epoch reference of 1970-01-01T00:00Z.
Know Your Data
People use various precisions in...
How do I add a tool tip to a span element?
...
Hi, Can someone clarify if this is standard in some/all HTML flavor?
– Jonathan dos Santos
Mar 20 '13 at 13:34
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Best way to check if a Data Table has a null value in it
...
I usually create an "Extensions" folder in some common library or in my DAL. Create a file called "DataTableExtensions.cs" and add that method. Next you would just add "using Name.Space.Extensions" to your cs files and have access...
Rails: create on has_one association
...
First of all, here is how to do what you want:
@user = current_user
@shop = Shop.create(params[:shop])
@user.shop = @shop
Now here's why your version did not work:
You probably thought that this might work because if User had a ha...
Replace selector images programmatically
...that has a drawable image resource set to a selector. How do I programmatically access the selector and change the images of the highlighted and non-highlighted state?
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