Questions on filtering and sorting an arraylist

Question

Hello All,
I'm trying to figure out a better way to do this code, but what I'm doing is taking an arrayList and filtering it using iter.remove(), based on a criteria I have, then take the results and sort them. The code below works, but I was seeing class cast exceptions when I tried to do a ss.addAll(list);
, but it worked when I just added the set object. Why is this and is there a better way to do all this?
Set set = new HashSet();
List retList = new ArrayList();
SortedSet ss = new TreeSet();
for(Iterator iter = list.iterator(); iter.hasNext();){
.//More code...
iter.remove();
//Remove duplicates.
set.addAll(list);
ss.add(set);
retList.addAll(set);
return retList;

Answer 1

Your current code is adding the set (the hash set) as one element (the only element?) of the sorted set. Is this what you want to do? Would you rather add each element of the set to the sorted set?
I don't know about the class cast exceptions. If you want somebody's comment on this part, you may consider posting code and stack trace.
I think I'd rely on Collections.sort() for sorting rather than TreeSet. If you prefer TreeSet, why not skip the hash set in between?
Hope this helps.
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