Private vs. Public members in practice (how important is encapsulation?) [closed]

Answer 1

Yes, encapsulation matters. Exposing the underlying implementation does (at least) two things wrong:

1. Mixes up responsibilities. Callers shouldn't need or want to understand the underlying implementation. They should just want the class to do its job. By exposing the underlying implementation, you're class isn't doing its job. Instead, it's just pushing the responsibility onto the caller.
2. Ties you to the underlying implementation. Once you expose the underlying implementation, you're tied to it. If you tell callers, e.g., there's a collection underneath, you cannot easily swap the collection for a new implementation.

These (and other) problems apply regardless of whether you give direct access to the underlying implementation or just duplicate all the underlying methods. You should be exposing the necessary implementation, and nothing more. Keeping the implementation private makes the overall system more maintainable.