Review (Updated) : 4884238 : Constants for Standard Charsets

[Ulf Zibis]

No answer ?
Especially on:
   static constant vs. static method

-Ulf


Am 20.04.2011 13:47, schrieb Ulf Zibis:
> Am 20.04.2011 02:23, schrieb Mike Duigou:
>> On Apr 19 2011, at 04:52 , Ulf Zibis wrote:
>>> I think, we should catch the problem at the source. ... In my approach from Bug 100098 - Make 
>>> sun.nio.cs.* charset objects light-weight such a class is named 'FastCharset'.
>> Unfortunately any we at a very late stage in Java 7's development and the degree of change 
>> required by 100098 are not possible.
>
> Yes, that's right. For that reason I have suggested an intermediate solution to avoid the 
> additional, later not removable StandardCharset(s) class.
>
>>   This issue itself may also be rejected solely for missing impending deadlines.
> Should there something be done for that?
>
>>> So I tend to prefer the original request from 4884238 (have the canonical names as constants), 
>>> as the lookup via Charset.forName(...) then could be very fast compared to the anyway following 
>>> heavy de/encoding work.
>> I think that in most uses a constant of the Charset is more useful as that's what's desired for 
>> use. I am not opposed to having visible constants for the charset names but I don't think it's as 
>> useful as the Charset objects. The performance of Charset.forName() is a separate matter.
>
> Thinking more I agree to some direct access to the standard charsets, because Charset.forName(..) 
> potentially needs extra exception handling. But is there a must for static constants? I think we 
> could have lazy initialized static methods, so (1) only the Charset class of request should be 
> loaded, (2) separate StandardCharset(s) class and discussion about the naming becomes superfluous, 
> (3) the small short cut cache in Charset remains it's proper function (otherwise the last 2, 
> UTF_16BE, UTF_16LE are cached), and (4) we could profit from it in Charset.defaultCharset() for 
> the fall-back case:
>  622                     defaultCharset = UTF_8();
>
> I still think, we should have constants for the canonical charset names: Charset.UTF_8 = "UTF-8"; 
> etc...
>
> Additionally consider, that in many real world cases not the charset, but it's de/encoder is of 
> interest, so the programmer anyway needs to define a static constant, if for performance reason it 
> should be reused:
>     static final CharsetDecoder UTF_8_DECODER = UTF_8.newDecoder();
>
> Here my new suggestion:
>
> public abstract class Charset implements Comparable<Charset> {
>     static final String UTF_8 = "UTF-8";
>     ...
>     static final Charset UTF_8() {
>         return forName(UTF_8); // Note that recently used charsets are hold in a small short cut 
> cache.
>     }
>     ...
> }
>
> -Ulf
>
>
>