AsyncTask not calling onProgressUpdate，onPostExecute

Question

我想了解在Android上使用AsyncTask并为此目的，我开发了这个简单的代码。

令人惊讶的是，doInbackground被正确调用，我看到日志但其他两个方法没有被调用。

我错过了什么吗？

感谢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"); 
     } 
    } 

[编辑]

有了这个代码的所有作品的权利以外的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); 
} 

在这里，你可以看到我的logcat的截图

Answer 1

方法签名是错误的。它应该看起来像：

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

此外，我建议您使用@Override注释。这样，如果您试图覆盖错误的方法，您将收到编译时错误。

编辑： 您发布onProgressUpdate的签名是错误的。它应该是：

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

Answer 2

AsyncTask拥有onProgressUpdate（Void ...）方法，您可以调用每个迭代或每次在doInBackground（）中通过调用publishProgress（）完成进度。

参考docs更多细节

所以应该看上去像个这样的：

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); 
    } 
}