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From: Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: How to convert image into Hex 2 Dimensional Array?
Date: Wed, 08 May 2013 12:52:54 -0400
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On 5/8/2013 11:22 AM, Daniel Pitts wrote:
> On 5/8/13 6:57 AM, lipska the kat wrote:
>> On 08/05/13 14:19, Daniele Futtorovic wrote:
>>> On 08/05/2013 10:06, lipska the kat allegedly wrote:
>>>>        Byte[][] bytes = new Byte[width][height];
>>>
>>> Lipska, mind the difference between Byte and byte. That code above is
>>> extremely bad advice.
>>
>> Why? it's common practice these days to eschew primitives and use
>> (autoboxing) classes
> Common practice where? Cite a credible source or I'll be forced to think
> that you are just making up facts to support your mistake.  My 4 year
> old daughter does that; you want to be more credible than my 4 year old,
> don't you?
>
>> it's more consistent in OO code and, as I
>> understand things, post autoboxing, the following two lines are
>> logically equivalent.
>>
>> 1. Byte[][] bytes = new Byte[width][height];
>> 2. byte[][] bytes = new byte[width][length]
>
> Even ignoring the typos, those are nothing alike.
>
> Auto-boxing is a convenience, but does not make those two things the
> same, even by a long shot.

    For example, consider what happens when `int x = bytes[0][0];'
immediately follows either of the above.  In case 2, it sets x
to zero.  In case 1, the JVM throws NullPointerException.  That's
not "logically equivalent" in my book!

>[...]
> Personally my decision on whether to use Byte vs byte would hinge solely
> on the question "do I want to store nulls in this?"

     Or on "Do I want to put it in a Collection?"

     There's also the matter of the memory footprint, even if
"efficiency" is a dirty word in some circles.  Version 1 will
use four times (32-bit JVM) or eight times (64-bit) as much
memory as version 2.  Image sizes vary, but even a fairly modest
640x480 has 300K pixels -- so using Byte[][] instead of byte[][]
would cost an extra 0.9MB or 2.1MB.  Even if I had the desire to
store nulls, a bloat of such proportions would probably prompt
me to use byte[][] and seek another way to represent whatever
I wanted the nulls to stand for.

-- 
Eric Sosman
esosman@comcast-dot-net.invalid