Enum enhancement

[Maurizio Cimadamore]

On 07/12/2018 14:36, Tagir Valeev wrote:
> As for (2) probably Optional<E> findValue(String name) would be better, as
> you may decide what to do if it's absent using all the optional API.

I like this suggestion!

Maurizio

>
> With best regards,
> Tagir Valeev.
>
> пт, 7 дек. 2018 г., 21:28 Brian Goetz brian.goetz at oracle.com:
>
>> (1) is already tracked as
>>
>>       https://bugs.openjdk.java.net/browse/JDK-8073381
>>
>> It is not as "easy" as you think in that these enum methods are
>> generated by the compiler, not as ordinary library code, but it's not
>> prohibited.
>>
>> (2) is not unreasonable.  As there's no language component to it, you
>> could take this directly to corelibs-dev for further evaluation.
>>
>> On 12/7/2018 9:13 AM, Giguere, Thierry wrote:
>>> Hello,
>>>
>>> Related to the follow link and JEP 301<https://openjdk.java.net/jeps/301>
>> :
>>>
>> http://mail.openjdk.java.net/pipermail/amber-spec-experts/2018-December/000876.html
>>> What is also missing and long-time due for enum right now and could be
>> added quickly is more methods:
>>> 1) We need to be able to iterate efficiently on enum. Currently calling
>> method T[] values() duplicate the internal array. Moreover you need to go
>> through method Arrays.stream() to convert the newly created array to
>> stream. Adding a stream() method and a forEach() method would help fix this
>> problem. Optionally a iterator() method could be provided
>>>         Arrays.stream(MyEnum.values()).forEach();
>>>
>>> could be replaced by something like :
>>>
>>>         MyEnum.forEach();
>>>
>>> And
>>>
>>>         Arrays.stream(MyEnum.values()).map(...
>>>
>>> could be written :
>>>
>>>         MyEnum.stream().map(...
>>>
>>> 2) T valueOfOrDefault : pretty much like getOrDefault of the map
>> interface. This method don't throw exception and fallback on default value.
>> That would ease use of enum in stream / lambda programming
>>>               @Nonnull
>>>               MyEnum myEnum = MyEnum.DEFAULT_VALUE;
>>>
>>>               try {
>>>                     myEnum = MyEnum.valueOf(...);
>>>               } catch (NullPointerException | IllegalArgumentException e)
>> {
>>>                     // Just keep going with on the default value
>>>               }
>>>
>>> Since exception are thrown it doesn't fit very well in stream / lambda
>> usage. Something like this :
>>> MyData.stream().map(MyEnum::valueOf).forEach()
>>>
>>> Must be converted to :
>>>
>>>                   MyData.stream().map(d -> {
>>>                                  try {
>>>                                                   return
>> MyEnum.valueOf(...);
>>>                                  } catch (Exception e) {
>>>                                                   return
>> MyEnum.DEFAULT_VALUE;
>>>                                                 }
>>>                   }).forEach();
>>>
>>> It would be great to write at least something like :
>>>
>>>                   MyData.stream().map(d -> MyEnum.valueOfOrDefault(d,
>> MyEnum.DEFAULT_VALUE)).forEach();
>>> My feeling is these enhancement could be easily and quickly added
>>>
>>> Thierry Giguère
>>>
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