npublic interface Collection<E>
extends Iterable<E> {
n // Basic
Operations
n
int size();
n
boolean isEmpty();
n
boolean contains(Object element);
n
boolean add(E element); // Optional
n
boolean remove(Object element); // Optional
n Iterator<E>
iterator();
n // Bulk Operations
// Generic interface !
n boolean containsAll(Collection<?> c);
n boolean addAll(Collection<? extends E> c); // Optional
n boolean removeAll(Collection <?> c); // Optional
n boolean retainAll(Collection <?> c); // Optional
n void clear();
// Optional
n // Array Operations
n Object[] toArray();
n <T> T[] toArray(T[] a);
n}