Question

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.

Answer 1

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.”