Is there any benefit in implementing a interface in a subclass even though the superclass implements the same interface

Question

When I was seeing the declaration of ArrayList

class ArrayList<E> extends AbstractList<E>
    implements List<E>, RandomAccess, Cloneable, java.io.Serializable

which implements List interface even though ArrayList's superclass AbstractList implements the same List interface.

abstract class AbstractList<E> extends AbstractCollection<E> implements List<E>

Similar declarations can be found on HashMap, LinkedHashMap declarations also.

In the declaration of LinkedHashMap, it implements Map interface only and not the other interfaces implemented by its superclass HashMap.

So there might be some benefits of having such declarations.

Answer 1

There are no functional benefits to declaring them again, it does not affect the behavior in any way.

I guess it's only added to make it clearer which interfaces are implemented.

Answer 2

This is done for documentation purposes only, to make it immediately clear to the user of the class which interfaces the class implements.

The redundant implements clause makes no difference to the compiler.