public void clear() {
   ArrayList<String> deletedList = new ArrayList<String>();
   deletedList.addAll(list);
   list.clear();
   adapter.notifyDataSetChanged();
   if (Utility.isTaskStopped(removeTask)) {
     removeTask = new RemoveFilterDBTask(deletedList);
     removeTask.executeOnExecutor(MyAsyncTask.THREAD_POOL_EXECUTOR);
   }
 }