Set

public interface Set<E> extends Collection<E> {
	int size();

	boolean isEmpty();

	boolean contains(Object o);

	Iterator<E> iterator();

	Object[] toArray();

	<T> T[] toArray(T[] a);

	boolean add(E o);

	boolean remove(Object o);

	boolean containsAll(Collection<?> c);

	boolean addAll(Collection<? extends E> c);

	boolean retainAll(Collection<?> c);

	boolean removeAll(Collection<?> c);

	void clear();

	boolean equals(Object o);

	int hashCode();
}