Guice annotatedWith for interface with Generics

Question

I have an interface TestInterface<U,V> that has many implementations, when I use Guice for binding I get a message saying TestInterface<Impl1, Impl2> not bound to an implementation. Following is the syntax I am using to bind interface with its implementations.

bind(TestInterface.class).annotatedWith(Names.named("Impl1Test")).to(Impl1.class);

p.s. I tested with a dummy interface but without generics and it worked fine, I reckon for generics something special needs to be done.

Answer 1

When binding generic types, you need to use a TypeLiteral rather than the raw class. Otherwise, Guice wouldn't be able to distinguish between the generic types. In your case, it would look something like this:

bind(new TypeLiteral<TestInterface<Impl1, Impl2>>(){})
    .annotatedWith(Names.named("Impl1Test"))
    .to(Impl1.class);

You may not even need the annotatedWith if you don't have other things that you want to bind as TestInterface<Impl1, Impl2>. Note the {} in the creation of the TypeLiteral... an anonymous subclass of TypeLiteral is necessary in order to have the generic type information preserved.