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Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time.

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On 1/14/2013 10:00 PM, GCRhoads@volcanomail.com wrote:
> I care because it has a large effect on the efficiency of the
> program.  With contiguous memory locations, the program's memory
> accesses will have a very high locality of reference resulting in a
> much faster average memory access time due to the computer's memory
> cache.

Are you also properly performing loop tiling to make sure that you 
maximize cache reuse, testing and choosing optimal loop unrolling 
parameters, and otherwise applying superoptimization techniques to your 
code? If the answer to that question was either "no" or "I don't know 
what you're saying," then I'll point out that the default 
characteristics of Java's memory management is good enough performance 
for you. If the answer was "yes", I will point out that you are almost 
certainly using the wrong language.

I will also point out that doing |new int[5][10]| will almost certainly 
be special-cased by the JVM into a dense multidimensional array (I 
recall seeing some mention of multidimensional arrayOops when I was 
poking about in OpenJDK to see if System.arraycopy might be using 
copy-on-write).

-- 
Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth

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Array of a Class Type that contains an array where the sizes of the array are not known at compile time. GCRhoads@volcanomail.com - 2013-01-13 17:38 -0800
  Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-01-13 18:56 -0800
    Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. GCRhoads@volcanomail.com - 2013-01-14 13:36 -0800
      Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-01-14 16:59 -0500
        Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. GCRhoads@volcanomail.com - 2013-01-14 20:00 -0800
          Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. GCRhoads@volcanomail.com - 2013-01-14 20:04 -0800
            Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Patricia Shanahan <pats@acm.org> - 2013-01-14 23:44 -0800
            Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-01-15 09:07 -0500
          Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2013-01-15 09:06 +0200
          Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-01-15 08:32 -0500
          Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Lew <lewbloch@gmail.com> - 2013-01-15 11:19 -0800
          Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Joshua Cranmer <Pidgeot18@verizon.invalid> - 2013-01-15 13:52 -0600
      Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Roedy Green <see_website@mindprod.com.invalid> - 2013-01-15 20:56 -0800
  Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. markspace <markspace@nospam.nospam> - 2013-01-13 19:01 -0800
    Re: Array of a Class Type that contains an array where the sizes of the array are not known at compile time. Lew <lewbloch@gmail.com> - 2013-01-13 21:39 -0800

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