public ChartListAdapter(Activity activity) {
   this.setDownloadInfos(new ArrayList<AppStats>());
   this.layoutInflater = activity.getLayoutInflater();
   this.activity = activity;
   this.scale = activity.getResources().getDisplayMetrics().density;
   this.dateFormat = new SimpleDateFormat(Preferences.getDateFormatShort(activity));
 }
 @Override
 public void notifyDataSetChanged() {
   this.dateFormat = new SimpleDateFormat(Preferences.getDateFormatShort(activity));
   super.notifyDataSetChanged();
 }