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Groups > comp.lang.java.programmer > #25068
| Date | 2013-08-20 06:04 -0500 |
|---|---|
| From | Peter Olcott <OCR4Screen> |
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: Autoboxing and Performance ? |
| References | <fcudnTCLD6xZ3I7PnZ2dnUVZ_gadnZ2d@giganews.com> <wbsfj3kz9x6.1hthr4dxr2yvl$.dlg@40tude.net> <cLydnRPXuKJn2I7PnZ2dnUVZ_jydnZ2d@giganews.com> <slrnl16i32.q59.avl@gamma.logic.tuwien.ac.at> |
| Message-ID | <Wt2dnWWN8Yvf0I7PnZ2dnUVZ_r2dnZ2d@giganews.com> (permalink) |
On 8/20/2013 5:43 AM, Andreas Leitgeb wrote:
> Peter Olcott <OCR4Screen> wrote:
>> On 8/20/2013 5:20 AM, Joerg Meier wrote:
>>> On Tue, 20 Aug 2013 05:15:30 -0500, Peter Olcott wrote:
>>>
>>>> From Java A Beginner's Guide, Fifth Edition by Herbert Schildt, page 425:
>>>
>>>> class AutoBox3 {
>>>> public static void main(String args[]) {
>>>> Integer iOb;
>>>> iOb = 99;
>>>
>>>> // The following automatically unboxes iOb,
>>>> // performs the increment, and then reboxes
>>>> // the result back into iOb
>>>> ++iOb;
>>>
>>>> It seems to me that all this unboxing and reboxing is a complete waste
>>>> of CPU time. It would make much more sense to provide an
>>>> Integer.Increment() member function that directly operates on the
>>>> contained data.
>>>
>>>> Why does Java waste so much CPU resources with its unboxing and reboxing
>>>> in cases such as this, and not simply provide member functions that
>>>> directly operate on the contained data?
>>>
>>> Because IntegerS and other Number classes are immutable. The contained data
>>> is not allowed to be changed under any circumstances.
>>>
>>> Liebe Gruesse,
>>> Joerg
>>>
>>
>> So the original object is replaced with a new object?
>>
>> What is the benefit (of immutability) that is worth the cost of this
>> poor performance?
>
> The lesson probably should be, that if you intend to do math on
> a variable, that you should use the primitive types instead.
>
> class NoAutoBox {
> public static void main(String args[]) {
> int iOb;
> iOb = 99;
> ++iOb; // value is overwritten; no objects created.
> }
> }
>
> PS: doing math on them is not the only use for integral numeric types.
>
I am trying to understand the Java language design principles that are
underlying the reasoning why there is such a thing as unboxing and
reboxing. I can see why class objects should be kept in a box, no
unboxing or reboxing required.
I do not see why primitive objects must be kept in a box, or why they
must be unboxed and reboxed if they are to be operated upon.
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Autoboxing and Performance ? Peter Olcott <OCR4Screen> - 2013-08-20 05:15 -0500
Re: Autoboxing and Performance ? Joerg Meier <joergmmeier@arcor.de> - 2013-08-20 12:20 +0200
Re: Autoboxing and Performance ? Peter Olcott <OCR4Screen> - 2013-08-20 05:33 -0500
Re: Autoboxing and Performance ? Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-08-20 10:43 +0000
Re: Autoboxing and Performance ? Peter Olcott <OCR4Screen> - 2013-08-20 06:04 -0500
Re: Autoboxing and Performance ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-08-20 08:08 -0400
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-20 20:15 -0400
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-20 20:12 -0400
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-21 03:52 +0300
Re: Autoboxing and Performance ? Sebastian <news@seyweiler.dyndns.org> - 2013-08-21 07:27 +0200
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-21 18:43 -0400
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-22 08:08 +0300
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-22 07:56 +0300
Re: Autoboxing and Performance ? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-08-22 10:51 -0700
Re: Autoboxing and Performance ? Martin Gregorie <martin@address-in-sig.invalid> - 2013-08-22 19:36 +0000
Re: Autoboxing and Performance ? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-08-22 13:01 -0700
Re: Autoboxing and Performance ? Martin Gregorie <martin@address-in-sig.invalid> - 2013-08-22 21:19 +0000
Re: Autoboxing and Performance ? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-08-22 14:39 -0700
Re: Autoboxing and Performance ? markspace <markspace@nospam.nospam> - 2013-08-22 19:50 -0700
Re: Autoboxing and Performance ? Martin Gregorie <martin@address-in-sig.invalid> - 2013-08-23 23:16 +0000
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-24 17:20 +0300
Re: Autoboxing and Performance ? Lew <lewbloch@gmail.com> - 2013-08-23 11:08 -0700
Re: Autoboxing and Performance ? Joerg Meier <joergmmeier@arcor.de> - 2013-08-23 22:52 +0200
Re: Autoboxing and Performance ? Jim Gibson <jimsgibson@gmail.com> - 2013-08-23 16:38 -0700
Re: Autoboxing and Performance ? "John B. Matthews" <nospam@nospam.invalid> - 2013-08-23 06:17 -0400
Re: Autoboxing and Performance ? Jeff Higgins <jeff@invalid.invalid> - 2013-08-23 17:25 -0400
Re: Autoboxing and Performance ? Jeff Higgins <jeff@invalid.invalid> - 2013-08-25 18:34 -0400
Re: Autoboxing and Performance ? Jeff Higgins <jeff@invalid.invalid> - 2013-08-28 10:52 -0400
Re: Autoboxing and Performance ? Martin Gregorie <martin@address-in-sig.invalid> - 2013-08-23 23:37 +0000
Re: Autoboxing and Performance ? Robert Klemme <shortcutter@googlemail.com> - 2013-08-26 19:33 +0200
Re: Autoboxing and Performance ? Sven Köhler <remove-sven.koehler@gmail.com> - 2013-08-29 10:09 +0300
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-29 14:14 +0200
Re: Autoboxing and Performance ? Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-08-29 21:28 -0300
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-20 20:03 +0200
Re: Autoboxing and Performance ? Lew <lewbloch@gmail.com> - 2013-08-20 16:23 -0700
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-21 11:51 +0200
Re: Autoboxing and Performance ? Lew <lewbloch@gmail.com> - 2013-08-21 08:39 -0700
Re: Autoboxing and Performance ? lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-08-21 16:51 +0100
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-21 19:19 -0400
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-22 09:49 +0200
Re: Autoboxing and Performance ? Jan Burse <janburse@fastmail.fm> - 2013-08-21 11:54 +0200
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-20 20:06 -0400
Re: Autoboxing and Performance ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-08-20 21:19 -0400
Re: Autoboxing and Performance ? Joerg Meier <joergmmeier@arcor.de> - 2013-08-21 10:05 +0200
Re: Autoboxing and Performance ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-08-21 07:19 -0400
Re: Autoboxing and Performance ? Joerg Meier <joergmmeier@arcor.de> - 2013-08-22 00:18 +0200
Re: Autoboxing and Performance ? Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-08-21 19:58 -0400
Re: Autoboxing and Performance ? Lew <lewbloch@gmail.com> - 2013-08-21 08:36 -0700
Re: Autoboxing and Performance ? taqmcg@gmail.com - 2013-08-21 09:37 -0700
Re: Autoboxing and Performance ? Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2013-08-20 23:28 -0500
Re: Autoboxing and Performance ? lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-08-21 10:09 +0100
Re: Autoboxing and Performance ? Arne Vajhøj <arne@vajhoej.dk> - 2013-08-21 19:04 -0400
Re: Autoboxing and Performance ? Arivald <NOSPAMarivald@interia.pl> - 2013-08-22 07:39 +0200
Re: Autoboxing and Performance ? Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-08-29 01:42 -0300
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