Ace Java 2026: Rock Your 'Thinking in Java' Challenge!

When using interfaces, calling code can know what methods might be called from a class because interfaces define a set of methods that should be implemented by the class. However, calling code cannot know about the implementation details of the class (option A) or access its private member variables (option B). The inheritance hierarchy (option D) can be known, but this is not specific to the use of interfaces.