ad 1. It does not implement its methods.
ad 4. The purpose of one interface extending, not implementing another, is to build a more specific interface. For example, SortedMap
is an interface that extends Map
. A client not interested in the sorting aspect can code against Map
and handle all the instances of for example TreeMap
, which implements SortedMap
. At the same time, another client interested in the sorted aspect can use those same instances through the SortedMap
interface.
In your example you are repeating the methods from the superinterface. While legal, it's unnecessary and doesn't change anything in the end result. The compiled code will be exactly the same whether these methods are there or not. Whatever Eclipse's hover says is irrelevant to the basic truth that an interface does not implement anything.