AsyncTask onPostExecute never gets called

I am not sure what I am doing wrong but onPostExecute never gets called.

• Created a base class called BaseActivity.java
• From my original Activity I extended this class.
• Placed PostToOpenFeint class inside BaseActivity

• Called it from the UI thread from the main activity my doing:

  new PostToOpenFeint.execute();
  

The onPreExecute(), doInBackground(..) gets triggered, but for some reason the onPostExecute never gets called.

Thank you in Advance!

Dave

 private class PostToOpenFeint extends AsyncTask<Void, Void, Void> {
  /*
   * (non-Javadoc)
   * 
   * @see android.os.AsyncTask#doInBackground(Params[])
   */
  @Override
  protected Void doInBackground(Void... params) {
   // does all the work here
   return null;
  }


  /*
   * (non-Javadoc)
   * 
   * @see android.os.AsyncTask#onPostExecute(java.lang.Object)
   */
  @Override
  protected void onPostExecute(Void result) {
   // TODO Auto-generated method stub
   super.onPostExecute(result);
   Toast.makeText(MainScreen.this, "Done syncing", Toast.LENGTH_LONG).show();
  }

  /*
   * (non-Javadoc)
   * 
   * @see android.os.AsyncTask#onPreExecute()
   */
  @Override
  protected void onPreExecute() {
   // TODO Auto-generated method stub
   super.onPreExecute();
   Toast.makeText(MainScreen.this, "About to sync all your scores", Toast.LENGTH_LONG).show();
  }

---

Looking into it more, this is what I was able to observe. For example if I place this call:

 new PostToOpenFeint.execute();

right after onCreate of the Activity, then everything works fine. If I place this call say inside a button listener.

settingsButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
   new PostToOpenFeint.execute();
}
});

The onPostExecute() never gets called, not sure wh开发者_Go百科at I am doing wrong. The restriction I read was to call this from UI Thread and I am calling it from UI thread.

---

I had a similiar problem just now. I was extending AsyncTask<Integer,Integer,Integer> and my onPostExecute method looked like:

protected void onPostExecute(int result)

This seemed OK to me, but then again I'm more of a .NET guy than a Java guy. I changed it to:

protected void onPostExecute(Integer result)

because for some reason Java thinks there is a difference between int and Integer?

I think that your problem is that you're declaring the return type as void in your:

extends<Void,Void,Void>

That means no params, no progress and no result. If you want to execute something when it's done, I think you need to give it some kind of value like and integer or a boolean.

If you change your extends to:

<Void,Void,Integer>

Now your passing no params, not publishing any progress, but are returning a value. Change your onPostExecute method to accept an Integer:

protected void onPostExecute(Integer result)

Then change the return in your doInBackground method to something like:

return 1;

Then it should execute for you.

---

There's one more gotcha about AsyncTasks that I just spent half the day on:

The AsyncTask class must be loaded on the UI thread. This is done automatically as of JELLY_BEAN.

Says the documentation. On Gingerbread (and probably before), given the right circumstances, this leads to onPostExecute not being run. The solution, however, is easy, just a

new MyAsyncTask();

early in the UI thread so the class gets loaded before anything in the background can inadvertently load it.

I had used a static function in my AsyncTask subclass from a background thread that, depending on timing, got called before anything on the UI thread used that AsyncTask subclass, and bingo, a nice Heisenbug.

(Bear with me for answering this old, already answered question, but I didn't find that tidbit of info anywhere, and this is my first post)

---

Note that if you cancel the task via cancel(), onPostExecute() won't be called. Pretty logical, but simply overlooking a call to that method had me stumped.

---

My problem was that somehow I didn't @Override the onPostExecute method correctly. I fixed that by clicking right mouse button->source-> Override\Implement method.

Hopes it helps someone

---

Maybe the code in doInBackground() never returns?

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Just Add this to Code to your Activity. Its the problem of Async Task not initializing properly as it is supposed to do.

          try {
                Class.forName("android.os.AsyncTask");
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

---

Just change the parameters in onPostExecute

@Override
protected void onPostExecute(Void unused) {
...}

Now the method should be called.

---

Just return something rather than null, and it'll work!
eg:
return "done";

---

Just use the proper Parameters in onPostExecute, use public void onPostExecute(Boolean response) { } instead of public void onPostExecute(boolean response) { } this solved my problem

---

I was also facing the same problem what is was doing wrong is that I was trying to write the method in a different scope the method will only trigger when you write it after the doInBackground method and inside the PostToOpenFeint class (in this case)

---

In my case I called downloading a file in UI thread. Then refreshed a token in IO and tried to download a file in UI. Refreshing a token called AsyncTask (TokenRequestTask) and didn't call onPostExecute.

Because everything was made with coroutines, I didn't know where is a mistake. Then downloaded a file in Dispatchers.IO, and the problem disappeared.