Re: Help with an arraylist of subclass using generics

From:

Donkey Hottie <spam@fred.pp.fi>

Newsgroups:

comp.lang.java.programmer

Date:

21 May 2009 18:05:48 GMT

Message-ID:

<Xns9C12D69C1E4F4SH15SGybs1ysmajw54s5@62.237.120.180>

Alessandro <ale.mito@tiscali.it> wrote in
news:91e25502-c664-4370-9f53-f3b21fc9bfc4@s28g2000vbp.googlegroups.com:

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

Every time you call Iterator.next(), it advances to the next element. You
call next() many many times in that while loop, and it does not work how
you intend.

Just put a

     RicDataElement element = iter1.next() ;
     if (element instanceof RicDataCrossElement) {
         RicDataCrossElement crossElm = (RicDataCrossElement)element;
     ...