Question

I have a button, and when I clicked on it, I load other Activity, onCreate of this I call a method that fills a spinner with data from a Web Service.

Well, When I click at this button the screen stay “frozen” and then shows the Activity. So, I thought that it could be a good thing shows a progress dialog for user, and after gets the return of the Web Service, ends the progress dialog.

I tried use Handler, and now I’m trying to use AsyncTask, but, geting NullPointerException, because my program is filling spinner before web service get called.

private void fillSpinner(){
    //runWebService();
    new CallWebServiceAsyncTask().execute(null);

    mAdapter = new PlanesAdapter(this, allPlanes);
    mList.setAdapter(mAdapter);
}


class CallWebServiceAsyncTask extends AsyncTask<Void, Void, Void> {

 private ProgressDialog progressDialog;

 @Override
 protected void onPreExecute() {

    progressDialog = new ProgressDialog(PlanesActivity.this);
    progressDialog.setMessage("Loading...");
    progressDialog.show();

 }

@Override

 protected Void doInBackground(Void... v) {

    runWebService();
    return null;

 }

 @Override

    protected void onPostExecute(Void result) {

    progressDialog.dismiss();

 }

}

Answer 1

because my program is filling spinner before web service get called.

you should fill data after getting data in onPostExecute Method

 @Override

    protected void onPostExecute(Void result) {

    progressDialog.dismiss();

    mAdapter = new PlanesAdapter(this, allPlanes);
    mList.setAdapter(mAdapter);

 }