- int size();
- boolean isEmpty();
- boolean contains(Object o);
- Iterator iterator();
- Object[] toArray();
- T[] toArray(T[] a);
- boolean add(E e);
- boolean remove(Object o);
- boolean containsAll(Collection<?> c);
- boolean addAll(Collection<? extends E> c);
- boolean removeAll(Collection<?> c);
- boolean retainAll(Collection<?> c);
- void clear();