How can I determine the type of object an ArrayList iterator will return next?

I have an ArrayList and I am using an iterator to run through it. I need to find out what type of object is next:

Iterator vehicleIterator = vehicleArrayList.iterator();

while(vehicleIterator.hasNext())
{
     //How do I find the type of object in the arraylist at this point
     // for example, is it a car, bus etc... 
}

Thanks