Dependency Injection and Java packages

Question

I'm doing a project that has a couple of packages. All my classes are implemented according to Dependency Injection ideias.

Now, there will be some place, in my application, that'll have the responsability of instantiating all the objects (actually I'm using an IoC Container for that, but that shouldn't matter) -- the so called Composition Root.

Now, the problem lies in the fact that, at least to my understanding, the composition root will have to know all the classes that'll be used of the system. That is, all the classes will have to be marked as public.

I could define for each package a Package Composition Root and then call each one of them from the system's composition Root but that doesn't seem that great of an idea.

In C#, for example, the situation is not so grave as there is not the package-protected access modifier -- there's internal (accessible for all the elements of the current assembly), instead.

How do you guys generally handle this?

Answer 1

Most containers get around access restrictions by using reflection. However this is just a hack to make you feel like you have some protection when actually relfection allows you to ignore the access modifiers.

IMHO, if you are accessing a class in another package you should be clear about this and give it an appropriate access modifier.