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Re: number to byte[]

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On 10/17/2015 5:03 PM, Askfor wrote:
> On 10/17/2015 02:03 PM, Eric Sosman wrote:
>> On 10/17/2015 4:02 AM, Askfor wrote:
>>> I am trying to get 4 byte[] representation of an integer, which might be
>>> 32 bit long.
>>>
>>> Obviously, I could AND with 255 and take byteValue(), then shift 8 times
>>> to the right and repeat the process 3 times. Is there any more elegant
>>> way ?
>>
>>      I can't think of one, off-hand.
>>
>>      But *why* do you want this four-byte array?  Are you planning to
>> write it to some output destination?  If so, perhaps you should use a
>> DataOutputStream (or other DataOutput implementation) and call its
>> writeInt() method.  Or, perhaps you should use an IntBuffer.  What
>> are you trying to do?
>>
>
> It is going to be a part of a data header, which needs to be of fixed
> length. Also it will contain a value of an offset which cabn't be longer
> than 32-bits. So, I don't care how big int actually is, as long as it is
> big enough to hold 32 bit unsigned value.

     It's probably simplest just to read and write the int directly,
letting the stream (or buffer) take care of assembling and disassembling
the bytes.  Classes that implement DataOutput and DataInput already have
the necessary machinery, provided you want BigEndian byte order.  If you
need LittleEndian, I think you can manage it with a Buffer.

     (I didn't mention it before, but RandomAccessFile can also read and
write BigEndian integers.)

> I started with serialization, too, but I realized it won't work.

     I didn't suggest serialization.  Perhaps you've confused DataOutput
with ObjectOutput; they are not the same.

-- 
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM

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number to byte[] Askfor <askfor@nowhere.net> - 2015-10-17 10:02 +0200
  Re: number to byte[] Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-10-17 08:03 -0400
    Re: number to byte[] Askfor <askfor@nowhere.net> - 2015-10-17 23:03 +0200
      Re: number to byte[] Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-10-17 17:45 -0400
        Re: number to byte[] Askfor <askfor@nowhere.net> - 2015-10-18 12:13 +0200
          Re: number to byte[] Askfor <askfor@nowhere.net> - 2015-10-18 12:44 +0200
            Re: number to byte[] Lew <lewbloch@gmail.com> - 2015-11-29 23:07 -0800
          Re: number to byte[] Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-10-18 08:40 -0400
      Re: number to byte[] Nigel Wade <nmw@ion.le.ac.uk> - 2015-10-19 10:43 +0100
        Re: number to byte[] Wayne <nospam@all.invalid> - 2015-10-20 00:45 -0400
        Re: number to byte[] Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2015-10-20 13:35 -0700
  Re: number to byte[] Lothar Kimmeringer <news200709@kimmeringer.de> - 2015-10-25 10:22 +0100

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