java 源代码里的failure mode

private class Itr implements Iterator<E> {
        int cursor;       // index of next element to return
        int lastRet = -1; // index of last element returned; -1 if no such
        int expectedModCount = modCount;

        public boolean hasNext() {
            // Racy but within spec, since modifications are checked
            // within or after synchronization in next/previous
            return cursor != elementCount;
        }
        
        ......
        public void remove() {
            if (lastRet == -1)
                throw new IllegalStateException();
            synchronized (Vector.this) {
                checkForComodification();
                Vector.this.remove(lastRet);
                expectedModCount = modCount;
            }
            cursor = lastRet;
            lastRet = -1;
        }
        
        final void checkForComodification() {
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();
        }
}

会抛出ConcurrentModificationException