title: UI Frozen during NotifyDataSetChanged Array Adapter
body: <p>I'm searching some pages from facebook and then downloading their pictures.
  i want to view them immediately in my list and update the adapter everytime i download a new picture. i'm using the same method in one other activity and it works, but here i'm using a dialog and it freeze my UI till everything is finished, even if i'm doing it in background. why?</p>
  
  <pre><code>private synchronized void getUserLikesImages() {AsyncTask&lt;Void, Void, Bitmap&gt; task = new AsyncTask&lt;Void, Void, Bitmap&gt;() {
  
          @Override
          public Bitmap doInBackground(Void... params) {
          for(...){
                 //download one picture...
                 FacebookeventsActivity.this.runOnUiThread(new Runnable() {
                 public void run() {
                          pagesILikeArrayAdapter.notifyDataSetChanged();
                 }
              });
  
          }
        };
     task.execute();
     }
  </code></pre>
  
  <p>it works, but the UI is frozen till the end of the operations... i think it might be because my list is in a dialog and i'm running it on UIThread, but i don't know how to fix it.</p>