Help with an arraylist of subclass using generics

Hi all,

I have a static ArrayList "buffer" with many objects. All of them
belongs to 3 classes (RicDataCrossElement, RicDataTassiElement,
RicDataUpdElement) which are childs of RicDataElement class.

I need to extract every object from this list and do some actions
according to the different class.
I have errors in the following code, please could you help ?

Of course I'm also doing more and more "next()" and every time I'm
passing to the following item ... so that's wrong !

//START CODE
....
public static ArrayList<RicDataElement> buffer;
....
Iterator<? extends RicDataElement> iter1 = buffer.iterator();
      while (iter1.hasNext())
       {

                if(iter1.next() instanceof RicDataCrossElement){
                          RicDataCrossElement crossElm=
(RicDataCrossElement )iter1.next();
                ...
                 }
                else if(iter1.next() instanceof RicDataTassiElement){
                 RicDataTassiElement tassiElm=(RicDataTassiElement)
iter1.next();
                        ...

              }
                  else if(iter1.next() instanceof RicDataUpdElement){
                 RicDataUpdElement updElm=(RicDataUpdElement)iter1.next
();
                 ...
              }
     }
}
//END CODE

Thanks for any help and best regards,
Alessandro