Which interface enables traversal without exposing the underlying structure of a collection?

Which interface enables traversal without exposing the underlying structure of a collection?

• A. Iterable
• B. Iterator
• C. List
• D. Map

Answer: (B)

Traversing a collection without revealing its internal layout is achieved by the traversal interface that defines how to move through elements. The Iterator provides a simple, uniform way to walk through items one by one, without exposing how they’re stored. You call hasNext to see if more elements exist and next to retrieve the next element, while the collection’s internal structure (array, linked list, tree, etc.) remains hidden. This encapsulation is what keeps implementation details out of the consumer’s view. An Iterable merely promises that a collection can produce an Iterator, enabling traversal, but it doesn’t perform the traversal itself. A List or a Map are concrete data structures with their own storage and access patterns, and they don’t standardize the traversal contract the way Iterator does.

Traversing a collection without revealing its internal layout is achieved by the traversal interface that defines how to move through elements. The Iterator provides a simple, uniform way to walk through items one by one, without exposing how they’re stored. You call hasNext to see if more elements exist and next to retrieve the next element, while the collection’s internal structure (array, linked list, tree, etc.) remains hidden. This encapsulation is what keeps implementation details out of the consumer’s view.

An Iterable merely promises that a collection can produce an Iterator, enabling traversal, but it doesn’t perform the traversal itself. A List or a Map are concrete data structures with their own storage and access patterns, and they don’t standardize the traversal contract the way Iterator does.