如何改进Java泛型通配符签名

Question

I'm trying to create DI container get method, but struggling with signature. Currently I have this definition:

public Object get(Class<?> key) {
  // returns instance of `?`
}

The part of my code which I dont like much is usage of the get method:

IRouter router = (IRouter) container.get(IRouter.class);

where I have to cast return with (IRouter) . Any ideas how to change method signature to make usage like this?

IRouter router = container.get(IRouter.class);

Thanks in advance for any ideas!

Answer 1

By using a scoped method parameterized type :

public <T> T get(Class<T> key) {
  // ...
  return (T) foo;
}

Here I suppose that foo is not typed as T .
If it is already typed as T you can of course return it without cast.

You could so invoke it :

IRouter router = container.get(IRouter.class);