<p>Implementations of this interface expose a lock object via {@link #getLock()} so that callers can synchronize externally on that lock:</p> <pre> if (iterator instanceof Synchronizable) { Object element = null; synchronized (((Synchronizable)iterator).getLock()) { if (iterator.hasNext()) element = iterator.next(); } } </pre> <p>In the example above, the calls to {@code hasNext()} and {@code next()} are performed "atomically".</p>