if(neighbors1ID.equals(neighbors2ID)) {
intersection++;
neighbors1ID = iter1.hasNext() ? iter1.next() : null;
neighbors2ID = iter2.hasNext() ? iter2.next() : null;
}
else if(neighbors2ID.compareTo(neighbors1ID) > 0) {
neighbors1ID = iter1.hasNext() ? iter1.next() : null;
}
else // neighbors1ID > neighbors2ID
{
neighbors2ID = iter2.hasNext() ? iter2.next() : null;