So, seems like we naturally converged to the generics / typetoken /
literal / ... discussion which I wanted to avoid and open it separately
within
https://java.net/jira/browse/JSONB_SPEC-30 :)
Still plan to open/branch the discussion separately likely this week to
not spoil runtime/mapping topics with it, but here's some hints into the
thinking since we're at the topic already:
I don't feel like adding X times Y list/map specific methods into the
api brings much value compared to the complexity it adds.
The trouble with TypeTokens/Literals/Gafter's gadget/... aproach is
that those are just a different versions of the same side-effect - they
are not guaranteed to work. They happen to work because of the JDK
internal requirements, but there's no base for it in the Java language
specification and we should not be building other APIs on side-effects.
One place this has been discussed already is at [1], raised by Pavel
Bucek after a long discussion with Brian Goetz. I'd recommend to
read/evaluate this through. Generics in Java were designed for
compile-time, not for runtime - and should be used as such.
MartiNG
[1]
https://java.net/projects/websocket-spec/lists/jsr356-experts/archive/2014-05/message/0
On 23.02.15 10:04, Przemyslaw Bielicki wrote:
> Hi Eugen,
>
> thanks a lot for complete example! I think we should go TypeToken way.
>
> Przemyslaw
>
> On Sun, Feb 22, 2015 at 6:56 PM, Eugen Cepoi <cepoi.eugen_at_gmail.com
> <mailto:cepoi.eugen_at_gmail.com>> wrote:
>
> fromJson(json, MyPojo.class) returns an instance of MyPojo, no
> need to cast.
> How to deser to a list of MyPojo (or any other generic type)?
>
> List<MyPojo> fromJson(json, new TypeToken<List<MyPojo>>() {})
>
> An example of impl
> https://github.com/owlike/genson/blob/master/genson/src/main/java/com/owlike/genson/GenericType.java
>
> You can also have a look at guavas Typetoken impl which is more
> sophisticated.
>
> This should avoid all kind of casts when the user knows what the
> actual type should be.
>
> Le 22 févr. 2015 00:17, "Przemyslaw Bielicki" <pbielicki_at_gmail.com
> <mailto:pbielicki_at_gmail.com>> a écrit :
>
> Hi,
>
> Yes these methods are a bit redundant, I agree.
> Do you have better idea how to avoid casts and
> @SuppressWarnings("unchecked") annotation? Can we achieve this
> using combination of Class and TypeToken? Because forcing end
> users to do so (casts and suppress) stinks in a modern API.
>
> I have one more comment regarding POJO but don't have time to
> express myself ;)
>
> Stay tuned,
> Przemyslaw
>
--
Martin Grebac, SW Engineering Manager
Oracle Czech, Prague