A public static method to figure out 50 Friends with Android phones and send them apprequests

Common.java

public static void fbShareThisAppForAndroidUsers(final Facebook mFacebook, final Activity mActivity) {
		AsyncTask<Object, Object, Object> asyncTask = new AsyncTask<Object, Object, Object>() {

			private WeakReference<Activity> weakActivity;
			private Facebook facebook;

			@Override
			protected Object doInBackground(Object... params) {
				try {
					facebook = mFacebook;
					weakActivity = new WeakReference<Activity>(mActivity);
					if (mFacebook.isSessionValid()) {
						// String response =
						// mFacebook.request("me/friends?fields=devices");
						String response = HttpRequest.get(
								Constants.FB_GRAPH_API_URI + ("me/friends?fields=devices&limit=0&offset=0&access_token=")
										+ mFacebook.getAccessToken()).body();
						if (response == null)
							return null;
						JSONArray array = new JSONObject(response).getJSONArray("data");
						ArrayList<String> fbIdsToPrefillArray = new ArrayList<String>();
						for (int i = 0; i < array.length(); i++) {
							JSONObject object = (JSONObject) array.get(i);
							if (object.has("devices")) {
								String devicesNodeText = object.getString("devices");
								if (devicesNodeText.contains("Android")) {
									fbIdsToPrefillArray.add(object.getString("id"));
								}

							}

						}
						return fbIdsToPrefillArray;
					}
				} catch (Exception e) {
				}
				return null;
			}

			@Override
			protected void onPostExecute(Object result) {
				Bundle bundle = new Bundle();
				bundle.putString("message", "Try this " + weakActivity.get().getString(R.string.app_name)
						+ " on your Android phone and never miss to wish your facebook friend even when you are offline.");
				ArrayList<String> fbIdsArray = (ArrayList<String>) result;
				if (fbIdsArray != null) {
					StringBuilder toValueBuilder = new StringBuilder();
					int count = 50;
					for (String aFbId : fbIdsArray) {
						if (count-- > 0) {
							toValueBuilder.append(aFbId);
							toValueBuilder.append(",");
						}
					}
					int lastIndexOfComma = toValueBuilder.lastIndexOf(",");
					toValueBuilder.replace(lastIndexOfComma, lastIndexOfComma + 1, "");
					bundle.putString("to", toValueBuilder.toString());
				}
				facebook.dialog(weakActivity.get(), "apprequests", bundle, listener);
				super.onPostExecute(result);
			}
		};
		asyncTask.execute(null, null, null);

	}