a quick question about String

[Johannes Kuhn]

You are looking for Frozen Arrays: https://openjdk.java.net/jeps/8261007

- Johannes

On 30-Dec-21 17:12, Alexander Scherbatiy wrote:
> On 12/24/21 10:33 AM, Enrico Olivelli wrote:
> 
>> Alan,
>> are you talking about the fact that you cannot "wrap" an existing
>> byte[] that you know that you are already encoded ?
>>
>> In that case the main problem is that the String is supposed to be
>> immutable and when you pass the byte[] it must be copied in order to
>> prevent someone else to modify the contents of the array behind the 
>> String
> 
> In java desktop where are arrays which values once created are not 
> updated anymore.
> It needs to make a defensive copy of such arrays every time when the 
> arrays are used
> by other classes to prevent them from being modified outside (InputEvent 
> [1],  SunFontManager [2], JOptionPane [3]).
> 
> Would it be useful to have some kind of an immutable array in Java language
> which works in the same way as ordinary array except it is not to 
> possible to change
> its values after creation?
> 
> [1] 
> https://github.com/openjdk/jdk/blob/299022dfacbcb49e3bc5beca8ff9b1fca1101493/src/java.desktop/share/classes/java/awt/event/InputEvent.java#L218 
> 
> [2] 
> https://github.com/openjdk/jdk/blob/299022dfacbcb49e3bc5beca8ff9b1fca1101493/src/java.desktop/share/classes/sun/font/SunFontManager.java#L3337 
> 
> [3] 
> https://github.com/openjdk/jdk/blob/299022dfacbcb49e3bc5beca8ff9b1fca1101493/src/java.desktop/share/classes/javax/swing/JOptionPane.java#L2010 
> 
> 
> Thanks,
> Alexander.
>> Enrico
>>
>> Il giorno gio 23 dic 2021 alle ore 23:56 Simon Roberts
>> <simon at dancingcloudservices.com> ha scritto:
>>> I think there are two things at stake here, one is that as I 
>>> understand it,
>>> "new means new", in every case. This is at least partly why the
>>> constructors on soon-to-be value objects are deprecated; they become
>>> meaningless. The other is that if the presumption is that we should
>>> always intern new Strings, I must disagree. Pooling takes time and 
>>> memory
>>> to manage, and if there are very few duplicates, it's a waste of both. I
>>> believe it should be up to the programmer to decide if this is 
>>> appropriate
>>> in their situation. Of course, the GC system seems to be capable of
>>> stepping in in some incarnations, which adds something of a 
>>> counterexample,
>>> but that is, if I recall, configurable.
>>>
>>>
>>> On Thu, Dec 23, 2021 at 2:53 PM Xeno Amess <xenoamess at gmail.com> wrote:
>>>
>>>> never should，as Object can be use as lock.
>>>>
>>>> XenoAmess
>>>> ________________________________
>>>> From: core-libs-dev <core-libs-dev-retn at openjdk.java.net> on behalf of
>>>> Bernd Eckenfels <ecki at zusammenkunft.net>
>>>> Sent: Friday, December 24, 2021 5:51:55 AM
>>>> To: alan Snyder <fishgarage at cbfiddle.com>; core-libs-dev <
>>>> core-libs-dev at openjdk.java.net>
>>>> Subject: Re: a quick question about String
>>>>
>>>> new String() always creates a new instance.
>>>>
>>>> Gruss
>>>> Bernd
>>>> -- 
>>>> http://bernd.eckenfels.net
>>>> ________________________________
>>>> Von: core-libs-dev <core-libs-dev-retn at openjdk.java.net> im Auftrag von
>>>> Alan Snyder <javalists at cbfiddle.com>
>>>> Gesendet: Thursday, December 23, 2021 6:59:18 PM
>>>> An: core-libs-dev <core-libs-dev at openjdk.java.net>
>>>> Betreff: a quick question about String
>>>>
>>>> Do the public constructors of String actually do what their 
>>>> documentation
>>>> says (allocate a new instance), or is there some kind of compiler magic
>>>> that might avoid allocation?
>>>>
>>>>
>>> -- 
>>> Simon Roberts
>>> (303) 249 3613