Fwd: Single Abstract Method for SAMs cannot be polymorphic (original) (raw)

Brian Goetz brian.goetz at oracle.com
Wed Apr 3 05:11:33 PDT 2013

Depends what you mean by "temporary". It was a deliberate choice to leave things this way, so, while we might change our mind in a few years and add a syntax for generic lambdas, this is the way it will be for Java 8.

On 4/3/2013 6:57 AM, Grégoire Neuville wrote:

Thanks for the clarification. Is it a temporary or permanent limitation ?

On 2 April 2013 22:23, Brian Goetz <brian.goetz at oracle.com> wrote: Not actually true. SAM methods can be generic. However, the only way to assign to such a SAM is with a method reference to a generic method. There's no syntax for lambdas that allows you to specify the type params.

You should be able to use Gen::new in your example (though not sure if the wildcards are going to mess it up.)

On 4/2/2013 4:04 PM, Grégoire Neuville wrote: Hi all, The below code : public class TestGenericSAM { class Gen {} @FunctionalInterface interface CoArbitrary { abstract Gen coarbitrary(A a, Gen g); } void test() { CoArbitrary<?> coArb = (a, g) -> new Gen<>(); } } doesn't compile. I guess this is by design (the annotation alone is marked as erroneous by IntelliJ), but I'm just wondering why. Thanks a lot for any explanation !

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