import java.util.Iterator;

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

}