ProgressBar not updating with AsyncTask

I am using ProgressBar to try and display the progress of loading and saving a file. The ProgressBar appears, but stays at 0 until it closes when the task is complete. I've tried different approaches but it just doesn't update. Is there something wrong with the code?

class downloadData extends AsyncTask<Void, Integer, Void>
{

    @Override
    protected void onPreExecute()
    {
        super.onPreExecute();
    }

    @Override
    protected Void doInBackground(Void... params)
    {
        int count; 
        try 
        {

            URL url = new URL("http://google.com");
            URLConnection conexion = url.openConnection();
            conexion.connect();
            int lenghtOfFile = conexion.getContentLength();
            InputStream is = url.openStream();
            File testDirectory = new File(MainActivity.this.getFilesDir(), "downloadedData.txt");
            if (!testDirectory.exists()) 
            {
                testDirectory.mkdir();
            }
            FileOutputStream fos = new FileOutputStream(testDirectory+"/downloadedData.txt");
            byte data[] = new byte[1024];
            long total = 0;
            while ((count = is.read(data)) != -1) 
            {
                total += count;

                int neki = (int)(((double)total/lenghtOfFile)*100);
                this.publishProgress(neki);

                fos.write(data, 0, count);
            }
            is.close();
            fos.close();
        } 
        catch (Exception e) 
        {
            Log.e("ERROR DOWNLOADING","Unable to download" + e.getMessage());
        }

        return null;
    }

    @Override
    protected void onProgressUpdate(Integer... values)
    {
        super.publishProgress(values);
        progressDialog.setProgress(values[0]);

    }

    @Override
    protected void onPostExecute(Void result)
    {
        super.onPostExecute(result);
        progressDialog.dismiss();
    }
}

      

        
        
        
      

    

OnCreate

    progressDialog = new ProgressDialog(this);
    progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
    progressDialog.setCancelable(true);
    progressDialog.setMax(100);
    progressDialog.setMessage("Downloading Data");

      

        
        
        
      

    

And when the button is clicked that starts the download: progressDialog.show();