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Groups > comp.lang.java.programmer > #21529

Re: creating byte[] with subfields

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Jim Janney <jjanney@shell.xmission.com> writes:

> Roedy Green <see_website@mindprod.com.invalid> writes:
>
>> I often have to construct byte arrays with binary fields, or read
>> them.
>>
>> I use a ByteArrayOutputStream and a DataOutputStream to compose them.
>> I wondered if there is a simpler way, one that does not require
>> computing each byte individually with shifts.
>
> In C, sure.  Java by design doesn't allow those kinds of tricks.

The hotspot compiler might notice that you're shifting and masking by 8
bits and replace it with direct byte addressing.  That seems like a
straightforward optimization.  OTOH, the speed difference is probably
too tiny to notice anyway.

-- 
Jim Janney

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Thread

creating byte[] with subfields Roedy Green <see_website@mindprod.com.invalid> - 2013-01-18 00:35 -0800
  Re: creating byte[] with subfields Jim Janney <jjanney@shell.xmission.com> - 2013-01-18 08:31 -0700
    Re: creating byte[] with subfields Jim Janney <jjanney@shell.xmission.com> - 2013-01-18 10:29 -0700
  Re: creating byte[] with subfields Nigel Wade <nmw@ion.le.ac.uk> - 2013-01-18 16:23 +0000
  Re: creating byte[] with subfields Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-01-18 10:53 -0800
    Re: creating byte[] with subfields Roedy Green <see_website@mindprod.com.invalid> - 2013-01-18 14:23 -0800
      Re: creating byte[] with subfields Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-01-18 15:16 -0800
        Re: creating byte[] with subfields Roedy Green <see_website@mindprod.com.invalid> - 2013-01-18 23:24 -0800
          Re: creating byte[] with subfields Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-01-19 21:46 -0800
            Re: creating byte[] with subfields Joshua Cranmer <Pidgeot18@verizon.invalid> - 2013-01-20 11:01 -0600
              Re: creating byte[] with subfields Arne Vajhøj <arne@vajhoej.dk> - 2013-01-20 12:54 -0500
            Re: creating byte[] with subfields Arne Vajhøj <arne@vajhoej.dk> - 2013-01-20 12:51 -0500
        Re: creating byte[] with subfields Arne Vajhøj <arne@vajhoej.dk> - 2013-01-19 13:34 -0500
  Re: creating byte[] with subfields Arne Vajhøj <arne@vajhoej.dk> - 2013-01-18 20:33 -0500
    Re: creating byte[] with subfields Arne Vajhøj <arne@vajhoej.dk> - 2013-01-18 20:48 -0500

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