AsyncTask to call another function within class

Issue

Basically, do I have to put code I want to run on another thread inside doInBackground, or can I call another function/class/whatever-it-is-functions-are-called-in-JAVA within doInBackground and have it run asynchronously? IE: (example code I found online)

      protected String doInBackground(String... params) {
        for(int i=0;i<5;i++) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        TextView txt = (TextView) findViewById(R.id.output);
        txt.setText("Executed");
        return null;
  }  

is how I have seen it done, but can I instead do:

      protected String doInBackground(String... params) {
           postToServer(x,y,z,h);
      }  

and have it call a function I already wrote and then have that function run in another thread? Sometimes my HTTP server is a bit slow to respond (it is but a lowly testing server at the moment) and Android automatically pops up the kill process box if my postToServer() call takes more than 5 seconds, and also disables my UI until the postToServer() call finishes. This is a problem because I am developing a GPS tracking app (internally for the company I work for) and the UI option to shut the tracking off freezes until my postToServer() finishes, which sometimes doesn't ever happen. I apologize if this has been answered, I tried searching but haven't found any examples that work the way I'm hoping to make this work.

Solution

You can do that, but you will have to move the UI updates to onPostExecute as it is run on the UI thread.

public MyAsyncTask extends AsyncTask<foo, bar, baz> {

    ...

    protected String doInBackground(String... params) {
       postToServer(x,y,z,h);
    }  

    protected void onPostExecute(Long result) {
        TextView txt = (TextView) findViewById(R.id.output);
        txt.setText("Executed");
    }

    ....

}

You may want to pass in the TextView to the constructor of the AsyncTask and store it as a WeakReference. private final WeakReference textViewReference;

public MyAsyncTask(TextView txt) {
    textViewReference = new WeakReference<TextView>(txt);
}

And then in onPostExecute you would make sure that the TextView reference still exists.

protected void onPostExecute(Long result) {
    TextView txt = textViewReference.get();
    if (txt != null)
        txt.setText("Executed");
}

If you want to notify the user that the task is executing I would put that before invoking the AsyncTask.

 myTextView.setText("Update in progress...");
 new MyAsyncTask().execute();

then in onPostExecute set the TextView to say "Update complete."

Answered By - antew