Reified Generics (was Re: Expose elementType of EnumSet and EnumMap)

Gili cowwoc at
Sun Sep 22 13:17:28 UTC 2013

On 9/22/2013 5:17 AM, Remi Forax wrote:
>> I fail to see a problem here. In fact this is a good case why such
>> method is necessary - if generics get reified in Java 9 and designers
>> of EnumSet decide to remove redundant elementType field, all software
>> depending on existence of this field will break. If on the other hand
>> there was a getElementType() method in Java 8, it could be safely
>> changed to obtain element type through whatever new mechanism is
>> available and existing software using getElementType() keeps working
>> correctly.
> There is a lot of code that cast to T or to EnumSet<T> that will start 
> to fail at runtime if generics are reified. One possible way to avoid 
> that is to create a new collection API, another is to try to reuse 
> existing implementations with an opt-in mecanism. In the later case, 
> the same class will be seen refiied
> or not depending on how the collection is created, so enabling 
> reification will be done incrementally in that case.
> getElementType is a way to export a refied type, it will add burden to 
> mixed mode implementation.

     Are Reified Generics officially part of JDK9? (I hope so!) Is there 
an official announcement/link to that respect?


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