import java.util.Iterator;


public interface Set<E> extends Collection{
		
		/**Adds the specified element to this set if not already present*/
		public boolean add(E e);
		
		/**Adds all of the elements in the specified collection to this set if not already present*/
		public boolean addAll(Collection<? extends E> c);
		
		/**Removes all of the elements from this set*/
		public void clear();
		
		/**Returns true if this collection contains the specified element*/
		public boolean contains(Object o);
		
		/**Returns true if this set contains all of the elements in the specified collection*/
		public boolean containsAll(Collection<?> c);
		
		/**Compares the specified object with this set for equality*/
		public boolean equals(Object o);
		
		/**Returns the hash code value for this set*/
		public int hashCode();
		
		/**Returns true if this set contains no elements*/
		public boolean isEmpty();
		
		//will get this for free
		//**Returns an iterator over the elements in this set*/
		//public Iterator<E> iterator();
		
		/**Removes the specified element from this set, if it is present*/
		public boolean remove(Object o);
		
		/**Removes from this set all of its elements that are contained in the specified collection*/
		public boolean removeAll(Collection<?> c);
		
		/**Retains only the elements in this set that are contained in the specified collection*/
		public boolean retainAll(Collection<?> c);
		
		/**Returns the number of alements in this set (its cardinality*/
		public int size();
		
		/**Returns an array containing all the elements in this set*/
		public Object[] toArray();
		
		/**Returns an array containing all of the elements in this set, the runtime type 
		 * 
		 of the returned array is that of the specified array
		 */
		public <T> T[] toArray(T[] a);
		
		

	}