Android AsyncTask：黑屏而不是ProgressBar

我已经实现了一个

AsyncTask

，使用内容解析器从收件箱读取短信

我已经在

ProgressBar

的

onPreExecute

和

onPostExecute

中放置了相应的可见性代码，但是

ProgressBar

没有显示。相反，我被困在一个黑屏上，就像当前活动是在前一个活动之后加载的一样（甚至前一个活动的祝酒词也永远被困在那里）

  public class ReadingSMS extends AsyncTask<String, String, Cursor> {

        protected void onPreExecute() {
            super.onPreExecute();
            mLoadingIndicator.setVisibility(View.VISIBLE);
        }

        @Override
        protected void onPostExecute(Cursor result) {

            mLoadingIndicator.setVisibility(View.INVISIBLE);

            int indexDate = result.getColumnIndex("date");
            int indexBody = result.getColumnIndex("body");

            do {
                //  String str = "SMS From: " + smsInboxCursor.getString(indexAddress) +
                //        "\n" + smsInboxCursor.getString(indexBody) + "\n";
                //    arrayAdapter.add(str);

                if (!stopReading) {
                    Date date = new Date(Long.parseLong(result.getString(indexDate)));


                    String newDate = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss").format(date);
                    //DateTime fmt = DateTime.parse(date.toString(),DateTimeFormat.forPattern("EEE MMM dd HH:mm:ss z yyyy"));
                    //String formattedDate = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy").format(date);

                    // Toast.makeText(this,newDate,Toast.LENGTH_SHORT).show();

                    Transaction tr = new Transaction(ScrollingActivity.this);
                    if (tr.isTransaction(result.getString(indexBody))) {
                        Log.d("here now bro", "yea");
                        tr.msg = result.getString(indexBody);
                        tr.date = newDate;
                        tr.call(ScrollingActivity.this);


                    }
                }
            } while (result.moveToNext());


        }

        @Override
        protected Cursor doInBackground(String... params) {

            return refreshSmsInbox();

        }
    }

}

public Cursor refreshSmsInbox() {
    ContentResolver contentResolver = getContentResolver();
    Cursor smsInboxCursor = contentResolver.query(Uri.parse("content://sms/inbox"), null, null, null, null);
    int indexBody = smsInboxCursor.getColumnIndex("body");

    if (indexBody < 0 || !smsInboxCursor.moveToFirst()) return null;
    //   arrayAdapter.clear();
    return smsInboxCursor;
}

  Cursor result = null;
        try {
             result = new ReadingSMS().execute().get();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    // I put my code from onPostExecute here.