Why is this type not a valid substitute for the type parameter?

Question

I\'m experimenting with using generics to support a configurable structure of delegating objects (decorators, wrappers). I want to build a chain of delegators that implement

Answer 1

It looks like this is what you are trying to do.

static interface Delegator {
    }

    static class DelegatorChain, C> {
    }

    static interface Foo {
    }

    static class FooDelegator implements Delegator, Foo {
    }

    public static void main(String[] args) {
        DelegatorChain chain = new DelegatorChain();
    }

Your initial example does not compile because the types are not correct. The Generic type in DelegatorChain is a "FooDelegator" but the generic type required in the Delegator is "Foo". You'll need the extra generic type parameter that i provided in my answer to make it work as you intended.

You could also leave the constraint off entirely on DelegatorChain i.e. DelegatorChain.