Calling static generic methods

java generics static type-inference
fredoverflow picture fredoverflow · Mar 14, 2011 · Viewed 70k times · Source

I have come across a curious situation involving static generic methods. This is the code:

class Foo<E>
{
    public static <E> Foo<E> createFoo()
    {
        // ...
    }
}

class Bar<E>
{
    private Foo<E> member;

    public Bar()
    {
        member = Foo.createFoo();
    }
}

How come I don't have to specify any type arguments in the expression Foo.createFoo()? Is this some kind of type inference? If I want to be explicit about it, how can I specify the type argument?

Answer

Jon Skeet picture Jon Skeet · Mar 14, 2011

Yes, this is type inference based on the target of the assignment, as per JLS section 15.12.2.8. To be explicit, you'd call something like:

Foo.<String>createFoo();

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