如图java.util.*,AbstractSet<E> implements Set<E>,为什么HashSet<E> extends AbstractSet<E> implements Set<E>？" implements Set<E>"这里有重复吗？
java.util.*
AbstractSet<E> implements Set<E>
HashSet<E> extends AbstractSet<E> implements Set<E>
implements Set<E>
java collections interface
collections ×1
interface ×1
java ×1