ListView mit ViewHolder, ImageViews und AsyncTask

 @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        Collection collection = collectionList.get(i);

        Log.d(TAG, "element : " + i + " folderpath :" + collection.getFolderPath());
        ViewHolder holder;

        if(view == null){
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = inflater.inflate(R.layout.item_collection_row, null);
            holder = new ViewHolder();
            holder.name = (TextView) view.findViewById(R.id.textViewName);
            holder.date = (TextView) view.findViewById(R.id.textViewDate);
            holder.location = (TextView) view.findViewById(R.id.textViewLocation);
            holder.active = (TextView) view.findViewById(R.id.textViewActiveCollection);
            holder.count = (TextView) view.findViewById(R.id.textViewImageCount);
            holder.imageView[0] = (ImageView) view.findViewById(R.id.imageViewThumb0);
            holder.imageView[1] = (ImageView) view.findViewById(R.id.imageViewThumb1);
            holder.imageView[2] = (ImageView) view.findViewById(R.id.imageViewThumb2);
            holder.imageView[3] = (ImageView) view.findViewById(R.id.imageViewThumb3);
            holder.position = i;
            view.setTag(holder);
        }
        else{
            holder = (ViewHolder) view.getTag();
            holder.imageView[0].setImageBitmap(null);
            holder.imageView[1].setImageBitmap(null);
            holder.imageView[2].setImageBitmap(null);
            holder.imageView[3].setImageBitmap(null);
        }

        holder.name.setText(collection.getName());
        holder.date.setText(collection.getDate());
        holder.location.setText(collection.getLocation());
        holder.count.setText(String.valueOf(getImageCount((collection))));

        imagePaths = MediaManager.getFirstFourImagePaths(collection.getFolderPath());
        new ThumbnailTask(i, holder).execute(imagePaths);


        //highlighten um active collection vorzuheben
        //TODO kann in Fragment umgelagert werden listview.setSelected(i, true)....
        if( ((int)collection.getId()) == activeCollectionId){
            holder.active.setVisibility(View.VISIBLE);
            //view.setBackgroundColor(context.getResources().getColor(R.color.collection_highlight));
        }
        else{
            holder.active.setVisibility(View.INVISIBLE);
            //view.setBackgroundColor(context.getResources().getColor(R.color.bg_gray));
        }
        return view;
    }