AsyncTask not calling onProgressUpdate，onPostExecute

Question

我想了解在Android上使用AsyncTask併爲此目的，我開發了這個簡單的代碼。

令人驚訝的是，doInbackground被正確調用，我看到日誌但其他兩個方法沒有被調用。

我錯過了什麼嗎？

感謝advancde

public class DownloadFilesTask extends AsyncTask<Void, Void, Void> { 

     protected Void doInBackground(Void... params) { 
      try { 
       Log.i("Thread","1"); 
       Thread.sleep(1000); 
       Log.i("Thread","2"); 
       Thread.sleep(1000); 
       Log.i("Thread","3"); 
       Thread.sleep(1000); 
       Log.i("Thread","4"); 
       Thread.sleep(1000); 
       Log.i("Thread","5"); 
      } catch (InterruptedException e) { 
       e.printStackTrace(); 
      } 
      return null; 
     } 

     protected void onProgressUpdate(Void... progress) { 
      Log.i("Thread","onProgress"); 
     } 

     protected void onPostExecute(Void... result) { 
      Log.i("Thread","onPosts"); 
     } 
    } 

[編輯]

有了這個代碼的所有作品的權利以外的onProgressUpdate

public class DownloadFilesTask extends AsyncTask<Void, Integer, String> { 

public String doInBackground(Void... params) { 
    try { 
     int i = 0; 
     Log.i("Thread","1"); 
     Thread.sleep(1000); 
     publishProgress(i++); 
     Log.i("Thread","2"); 
     Thread.sleep(1000); 
     publishProgress(i++); 
     Log.i("Thread","3"); 
     Thread.sleep(1000); 
     Log.i("Thread","4"); 
     Thread.sleep(1000); 
     Log.i("Thread","5"); 
    } catch (InterruptedException e) { 
     e.printStackTrace(); 
    } 
    return "done"; 
} 

public void onProgressUpdate(int progress) { 
    Log.i("Thread","onProgress " + progress); 
} 

public void onPostExecute(String result) { 
    Log.i("Thread","onPosts " + result); 
} 

在這裏，你可以看到我的logcat的截圖

Answer 1

方法簽名是錯誤的。它應該看起來像：

protected void onPostExecute(Void result) { 
    Log.i("Thread","onPosts"); 
} 

此外，我建議您使用@Override註釋。這樣，如果您試圖覆蓋錯誤的方法，您將收到編譯時錯誤。

編輯： 您發佈onProgressUpdate的簽名是錯誤的。它應該是：

protected void onProgressUpdate(Integer... progress){} 

Answer 2

AsyncTask擁有onProgressUpdate（Void ...）方法，您可以調用每個迭代或每次在doInBackground（）中通過調用publishProgress（）完成進度。

參考docs更多細節

所以應該看上去像個這樣的：

public class DownloadFilesTask extends AsyncTask<Void, Integer, String> { 

    protected String doInBackground(Void... params) { 
     try { 
      int i = 0; 
      Log.i("Thread","1"); 
      Thread.sleep(1000); 
      publishProgress(i++); 
      Log.i("Thread","2"); 
      Thread.sleep(1000); 
      publishProgress(i++); 
      Log.i("Thread","3"); 
      Thread.sleep(1000); 
      Log.i("Thread","4"); 
      Thread.sleep(1000); 
      Log.i("Thread","5"); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     } 
     return "done"; 
    } 

    protected void onProgressUpdate(int progress) { 
     Log.i("Thread","onProgress " + progress); 
    } 

    private void onPostExecute(String result) { 
     Log.i("Thread","onPosts " + result); 
    } 
}