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From: Arved Sandstrom <asandstrom2@eastlink.ca>
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Subject: Re: Autoboxing and Performance ?
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On 08/20/2013 07:33 AM, Peter Olcott 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?

Not being facetious here. Just Google on immutability.

AHS

-- 
When a true genius appears, you can know him by this sign:
that all the dunces are in a confederacy against him.
-- Jonathan Swift