• 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();