onPostExecute doesn't run, @override doesnt work android development

Question

I've just gotten into android development, and while trying to create a login form i ran into some problems.

What I want to do is enter username and password and press login, when the login button is pushed I want it to do a JSON request with the account information to my server and get a response with whether or not the user is allowed to log in. If the user is allowed, I want to change to a new view.

My code receives the JSON information correctly, but from what I've understood the UI-code (pushing a new activity) should be done in onPostExecute(). My problem is that onPostExecute is never run, I've looked at other ppl with the same problem, but their solutions hasn't worked for me. What they have said is that i need to have an @Override before onPostExecute, but when I add that i get the compilation error that "the method does not override method from its superclass".

I've read solutions from people having that problem as well, and from what I have read the problem is that the method onPostExecute has to have the same parameters as the result parameter from doInBackground(). My problem is that I feel I already do, and when I try to look in what the superclass has (that is AsyncTask.java) it says that the method onPostExecute() looks like:

protected void onPostExecute(Result result) {
    }

But I have no idea what class Result belongs to..

networkingTask is run using this line:

new networkingTask().execute(url);

If anyone could help me I'd be eternally grateful! :)

This is what my code looks like

private class networkingTask extends AsyncTask {
   Context context;
    private networkingTask(Context context) {
        this.context = context.getApplicationContext();
    }

    public networkingTask() {
    }

    @Override
    protected JSONObject doInBackground(Object... params) {
        try {

            String urlString = (String) params[0];
            System.out.println(urlString);
            // Creating JSON Parser instance
            JSONParser jParser = new JSONParser();
            // getting JSON string from URL
            JSONObject json;
            json = jParser.getJSONFromUrl(urlString);

            String responseLogged =  json.getString("logged");
            System.out.println("can we log in?: "+ responseLogged);

            return json;

        } catch (JSONException e) {
            e.printStackTrace();
        }
           return null;
    }

     @Override
     protected void onPostExecute(JSONObject result) {
         String responseLogged = "";
         try {
             responseLogged = result.getString("logged");
         } catch (JSONException e) {
             e.printStackTrace();
         }

         if(responseLogged.equals("true")){  //Login = true
             Intent intent = new Intent(context, ShowListActivity.class);
             intent.putExtra(EXTRA_JSON_OBJECT, result.toString());
             startActivity(intent);
         }   else{ //Login = false
             System.out.println("wrong password");
         }

         return;
    }

}

Answer 1

In your line:

private class networkingTask extends AsyncTask

just change it to:

private class networkingTask extends AsyncTask<String, Void, JSONObject>

while String is the place for you to pass in the parameters, in your case it is url, the second parameter Void is for showing progress and the last one is the processed result to be passed from doInBackground to onPostExecute

For further explanation & info, please refer to Android Developers: AsyncTask

Answer 2

I think you may need to fill out the generic types for your AsyncTask. See the "Usage" section in the AsyncTask documentation.

Your class signature should look something like this:

private class networkingTask extends AsyncTask<Object, Void, JSONObject>

The types in the brackets here correspond to the argument types for doInBackground, onProgressUpdate, and onPostExecute, respectively, and are necessary if you're going to override these methods such that they are different from the generic method signatures.

Also, as a side note, it's a common convention in Java/Android to use upper CamelCase to start a class name. I'd also change the name of your class to "NetworkingTask" to help other developers looking at your code to better understand it.