ProgressDialog içinde AsyncTask ilerlemesini göstermiyor

Question

Çok sayıda çevrimiçi kaynağı kontrol etsem de, sorunu hala bulamıyorum. Görünüşe göre ProgressDialog iyi görünüyor, ancak ilerlemeyi güncellemek istediğimde, onProgressUpdate örneğinde her zaman boştur.

package com.async_tasks; 

public class UploadTask extends AsyncTask<Void,Integer,Void> implements Serializable {   
    private static final String TAG = UploadTask.class.getSimpleName(); 
    private ConnectionToServer _connectionToServer; 
    private TransferDetails _td; 
    private Activity _activity; 
    private ProgressDialog _progDialog; 
    private UploadTask _taskInstance; 

    public UploadTask(Activity activity, ConnectionToServer connectionToServer, TransferDetails td) { 

     _activity = activity; 
     _connectionToServer = connectionToServer; 
     _td = td; 
     _taskInstance = this; 
    } 

    @Override 
    protected void onPreExecute() { 

     _progDialog = new ProgressDialog(_activity); 
     String cancel = _context.getResources().getString(R.string.cancel); 

     _progDialog.setCancelable(false); 
     _progDialog.setTitle(_context.getResources().getString(R.string.uploading)); 
     _progDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER); 
     _progDialog.setProgress(0); 
     _progDialog.setMax(100); 
     _progDialog.setButton(DialogInterface.BUTTON_NEGATIVE, cancel, new DialogInterface.OnClickListener() { 
      @Override 
      public void onClick(DialogInterface dialog, int which) { 

       _taskInstance.cancel(true); 
      } 
     }); 

     _progDialog.show(); 

    } 

    @Override 
    protected Void doInBackground(Void... voids) { 

     //uploading file ... 
       float percent = (float) (fileSize - bytesToRead)/fileSize * 100; 
       publishProgress((int)percent);     
      } 

     } 
     catch (IOException e) { 
       // Handling exception 
     } finally { 

      if(bis!=null) { 
       try { 
        bis.close(); 
       } catch (IOException e) { 
        e.printStackTrace(); 
       } 
      } 
      clearMembers(); 

      } 
     } 

     return null; 
    } 

    @Override 
    protected void onProgressUpdate(Integer... progress) { 

     if(_progDialog!=null) { // <<------------ I suspect for some reason this is always false, as _progDialog is always null - But why?! 
      _progDialog.incrementProgressBy(progress[0]); 
     } 
    } 

    @Override 
    protected void onPostExecute(Void result) { 

     //The task is complete, clear members 
     clearMembers(); 
    } 

    private void clearMembers() { 

     _activity = null; 
     if(_progDialog!=null) { 
      _progDialog.dismiss(); 
      _progDialog = null; 
     } 
    } 
} 

Ve bu MainActivity gelen çağrıdır:

Bu

benim AsyncTask olduğunu

TransferDetails td = (TransferDetails) report.data(); 
ConnectionToServer conn = StorageServerProxyService.getConn(); 
UploadTask uploadTask = new UploadTask(MainActivity.this, conn, td); 
uploadTask.execute(); 

Answer 1

OnPreExecute (Değiştir) olarak aşağıda yöntemi:

@Override 
    protected void onPreExecute() { 

progDialog = new ProgressDialog(ActivityName.this); 
     String cancel = _context.getResources().getString(R.string.cancel); 

     _progDialog.setCancelable(false); 
     _progDialog.setTitle(_context.getResources().getString(R.string.uploading)); 
     _progDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER); 
     _progDialog.setProgress(0); 
     _progDialog.setMax(100); 
     _progDialog.setButton(DialogInterface.BUTTON_NEGATIVE, cancel, new DialogInterface.OnClickListener() { 
      @Override 
      public void onClick(DialogInterface dialog, int which) { 

       _taskInstance.cancel(true); 
      } 
     }); 

     _progDialog.show(); 

    }