[resteasy-dev] Lambda question

[Rostislav Svoboda]

> When I run
> 
> >     @Test
> >     public void test2()
> >     {
> >        MapFunction<String, Integer> fn = str -> Integer.valueOf(str);
> >        Class<?>[] typeArgs =
> > TypeResolver.resolveRawArguments(MapFunction.class, fn.getClass()); //
> > Using Jonathan Halterman's TypeResolver
> >        System.out.println("typeArgs.length: " + typeArgs.length);
> >        for (Class<?> clazz : typeArgs)
> >        {
> >           System.out.println(clazz);
> >        }
> >     }
> with openjdk 8, I get
> 
> > typeArgs.length: 2
> > class java.lang.String
> > class java.lang.Integer
> but when I run it with IBM jdk 8, I get
> 
> > typeArgs.length: 2
> > class org.jboss.resteasy.test.contextresolver.TypeResolver$Unknown
> > class org.jboss.resteasy.test.contextresolver.TypeResolver$Unknown
> 
> I see that IBM jdk 8 has sun.reflect.ConstantPool, but that doesn't seem
> to be enough.
> 
> I think we should revisit this issue when JDK 9 is released. It's
> probably too late to make a request, right?

I would say so, there was some deadline for proposals till the end of 2016 and planned release of Java 9 is July 2017.
Tomaz - any comment on this ? 

Rostislav

> -Ron
> 
> 
> On 04/07/2017 02:54 AM, Rostislav Svoboda wrote:
> > https://github.com/jhalterman/typetools#on-lambda-support
> >
> > Lambda type argument resolution is currently supported for:
> >      Oracle JDK 8
> >      Open JDK 8
> >
> > IBM JDK 8 will need some attention too.
> >
> > Rostislav
> >
> > ----- Original Message -----
> >> Hi Steven,
> >>
> >> That's really interesting. It works for both Oracle JDK 1.8.0_91 and JDK
> >> 9 build 163 from java.net. !!
> >>
> >> One problem I see is that Jonathan Halterman's TypeResolver class has
> >> the line
> >>
> >>> String constantPoolName = JAVA_VERSION < 9 ?
> >>> "sun.reflect.ConstantPool" : "jdk.internal.reflect.ConstantPool";
> >> so I don't think we could use it for any JDK < 9. Once JDK 9 stabilizes
> >> and Resteasy is releasing JDK 9 code, maybe it would be OK.
> >>
> >> Even better would be if Class.getGenericInterfaces() were to work in JDK
> >> 9, but, as of build 163, it doesn't.
> >>
> >> In any case, you've helped to verify that the solution requires external
> >> tricks. Let's hope that your "right approach" is followed.
> >>
> >> Thank you very much,
> >>
> >> Ron
> >>
> >> On 04/03/2017 01:49 PM, Steven Schlansker wrote:
> >>>> On Apr 3, 2017, at 10:11 AM, Ron Sigal <rsigal at redhat.com> wrote:
> >>>> ...
> >>>>
> >>>> So, it seems that, for lambdas, Java doesn't keep the implementation
> >>>> type
> >>>> and value of the type variable at run time. Does anyone have any ideas
> >>>> or
> >>>> tricks?
> >>> I did not have time to play with it myself, but I did run across this:
> >>> https://stackoverflow.com/questions/23863716/java-how-to-resolve-generic-type-of-lambda-parameter
> >>> maybe that helps?
> >>>
> >>> It sounds like the "right approach" would be to request Java stash the
> >>> type
> >>> information better for lambdas...
> >>>
> >> --
> >> My company's smarter than your company (unless you work for Red Hat)
> >>
> >> _______________________________________________
> >> resteasy-dev mailing list
> >> resteasy-dev at lists.jboss.org
> >> https://lists.jboss.org/mailman/listinfo/resteasy-dev
> >>
> 
> --
> My company's smarter than your company (unless you work for Red Hat)
> 
>