Iterator Implementation
I think your implementation is overall very good, two small comments:


Improving readability for return statement in hasNext to return examples.size() != index;
Making the examples field final: private final List&lt;Vector&gt; examples;


However, if the Vector class here is java.util.Vector you should know that it is considered deprecated in favor of the ArrayList class.

Also, since you create your iterator from a List&lt;Vector&gt; you could get an Iterator&lt;Vector&gt; by calling list.iterator();