public void prioritizeViewRange(int firstVisibleItem, int lastVisibleItem, int prefetchBuffer) {
    if ((lastVisibleItem < firstVisibleItem) || (sectionKeys.size() == 0)) {
      return;
    }

    // We want to prioritize requests for items which are visible but do not have pictures
    // loaded yet. We also want to pre-fetch pictures for items which are not yet visible
    // but are within a buffer on either side of the visible items, on the assumption that
    // they will be visible soon. For these latter items, we'll store the images in memory
    // in the hopes we can immediately populate their image view when needed.

    // Prioritize the requests in reverse order since each call to prioritizeRequest will just
    // move it to the front of the queue. And we want the earliest ones in the range to be at
    // the front of the queue, so all else being equal, the list will appear to populate from
    // the top down.
    for (int i = lastVisibleItem; i >= 0; i--) {
      SectionAndItem<T> sectionAndItem = getSectionAndItem(i);
      if (sectionAndItem.graphObject != null) {
        String id = getIdOfGraphObject(sectionAndItem.graphObject);
        ImageRequest request = pendingRequests.get(id);
        if (request != null) {
          ImageDownloader.prioritizeRequest(request);
        }
      }
    }

    // For items which are not visible, but within the buffer on either side, we want to
    // fetch those items and store them in a small in-memory cache of bitmaps.
    int start = Math.max(0, firstVisibleItem - prefetchBuffer);
    int end = Math.min(lastVisibleItem + prefetchBuffer, getCount() - 1);
    ArrayList<T> graphObjectsToPrefetchPicturesFor = new ArrayList<T>();
    // Add the IDs before and after the visible range.
    for (int i = start; i < firstVisibleItem; ++i) {
      SectionAndItem<T> sectionAndItem = getSectionAndItem(i);
      if (sectionAndItem.graphObject != null) {
        graphObjectsToPrefetchPicturesFor.add(sectionAndItem.graphObject);
      }
    }
    for (int i = lastVisibleItem + 1; i <= end; ++i) {
      SectionAndItem<T> sectionAndItem = getSectionAndItem(i);
      if (sectionAndItem.graphObject != null) {
        graphObjectsToPrefetchPicturesFor.add(sectionAndItem.graphObject);
      }
    }
    for (T graphObject : graphObjectsToPrefetchPicturesFor) {
      URI uri = getPictureUriOfGraphObject(graphObject);
      final String id = getIdOfGraphObject(graphObject);

      // This URL already have been requested for pre-fetching, but we want to act in an LRU manner,
      // so move
      // it to the end of the list regardless.
      boolean alreadyPrefetching = prefetchedProfilePictureIds.remove(id);
      prefetchedProfilePictureIds.add(id);

      // If we've already requested it for pre-fetching, no need to do so again.
      if (!alreadyPrefetching) {
        downloadProfilePicture(id, uri, null);
      }
    }
  }
 public static <T> ArrayList<T> arrayList(T... ts) {
   ArrayList<T> arrayList = new ArrayList<T>(ts.length);
   for (T t : ts) {
     arrayList.add(t);
   }
   return arrayList;
 }
 public static <T> List<T> asListNoNulls(T... array) {
   ArrayList<T> result = new ArrayList<T>();
   for (T t : array) {
     if (t != null) {
       result.add(t);
     }
   }
   return result;
 }
  public List<T> getGraphObjectsById(Collection<String> ids) {
    Set<String> idSet = new HashSet<String>();
    idSet.addAll(ids);

    ArrayList<T> result = new ArrayList<T>(idSet.size());
    for (String id : idSet) {
      T graphObject = graphObjectsById.get(id);
      if (graphObject != null) {
        result.add(graphObject);
      }
    }

    return result;
  }
  private void processImageResponse(
      ImageResponse response, String graphObjectId, ImageView imageView) {
    pendingRequests.remove(graphObjectId);
    if (response.getError() != null) {
      callOnErrorListener(response.getError());
    }

    if (imageView == null) {
      // This was a pre-fetch request.
      if (response.getBitmap() != null) {
        // Is the cache too big?
        if (prefetchedPictureCache.size() >= MAX_PREFETCHED_PICTURES) {
          // Find the oldest one and remove it.
          String oldestId = prefetchedProfilePictureIds.remove(0);
          prefetchedPictureCache.remove(oldestId);
        }
        prefetchedPictureCache.put(graphObjectId, response);
      }
    } else if (graphObjectId.equals(imageView.getTag())) {
      Exception error = response.getError();
      Bitmap bitmap = response.getBitmap();
      if (error == null && bitmap != null) {
        imageView.setImageBitmap(bitmap);
        imageView.setTag(response.getRequest().getImageUri());
      }
    }
  }
  private void onFriendPickerDone(FriendPickerFragment fragment) {
    FragmentManager fm = getSupportFragmentManager();
    fm.popBackStack();

    String results = "";

    Collection<GraphUser> selection = fragment.getSelection();
    if (selection != null && selection.size() > 0) {
      ArrayList<String> names = new ArrayList<String>();
      for (GraphUser user : selection) {
        names.add(user.getName());
      }
      results = TextUtils.join(", ", names);
    } else {
      results = "no friends";
    }

    showAlert("rar", results);
  }