通过迭代器访问Java的Collection的方法

interface Collection<E> extends Iterable<E> {
    
    int size();
    boolean isEmpty();
    boolean contains(Object o);
    Iterator<E> iterator();
    Object[] toArray();
    <T> T[] toArray(T[] a);
    default <T> T[] toArray(IntFunction<T[]> generator) {
        return toArray(generator.apply(0));
    }
    boolean add(E e);
    boolean remove(Object o);
    boolean containsAll(java.util.Collection<?> c);
    boolean addAll(java.util.Collection<? extends E> c);
    boolean removeAll(java.util.Collection<?> c);
    default boolean removeIf(Predicate<? super E> filter) {
        Objects.requireNonNull(filter);
        boolean removed = false;
        final Iterator<E> each = iterator();
        while (each.hasNext()) {
            if (filter.test(each.next())) {
                each.remove();
                removed = true;
            }
        }
        return removed;
    }
    boolean retainAll(java.util.Collection<?> c);
    void clear();
    boolean equals(Object o);
    int hashCode();
    @Override
    default Spliterator<E> spliterator() {
        return Spliterators.spliterator(this, 0);
    }
    default Stream<E> stream() {
        return StreamSupport.stream(spliterator(), false);
    }
    default Stream<E> parallelStream() {
        return StreamSupport.stream(spliterator(), true);
    }
}