AsyncTask “onPostExecute” method never called

Question

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

I read a lot of answers to similar problem and none of them worked for me.

I tried to replace the return declaration to void and to Integer and a lot of crazy things that work for other but not for me.

my asyncetask class:

    import static java.util.Arrays.asList;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.content.res.Resources;
import android.os.AsyncTask;
import android.widget.ImageView;

public class Async extends AsyncTask<Result, Void, Integer> {

            private static final String TAG = "UpdateUI";
            private static final int DELAY = 500;
            public static ImageView A1, A2, A3, A4, A5, A6, A7, A8, B1, B2, B3, B4, B5, B6,
                    B7, B8, C1, C2, C3, C4, C5, C6, C7, C8;
            public int dsc1, dsc2, dsc3, dsc4, dsc5, dsc6, dsc7, dsc8, pole;
            public static Resources mResources;
            public static List<ImageView> A ,B ,C ;
            private Activity mActivity;
            public ArrayList<Result> arr;

            Async(Activity activity) {
                mActivity = activity;   
            }

            @Override
            protected Integer  doInBackground(Result... params) {

                initializeVariables();
                mResources =  mActivity.getResources();
                ArrayList<Result> arr = new ArrayList<Result>();
                arr.add(params[0]);
                arr.add(params[1]);


                return 1;
            }

            @Override
            protected void onPostExecute(Integer result) {


                switch (arr.get(0).getPoleNumber()) {
                case 1:
                    A.get(arr.get(0).getPole()).setImageDrawable(arr.get(0).getImg());
                    break;
                case 2:
                    B.get(arr.get(0).getPole()).setImageDrawable(arr.get(0).getImg());
                    break;
                case 3:
                    C.get(arr.get(0).getPole()).setImageDrawable(arr.get(0).getImg());
                    break;
                }

                   switch (arr.get(1).getPoleNumber()) {
                    case 1:
                        A.get(arr.get(1).getPole()).setImageDrawable(arr.get(1).getImg());
                        break;
                    case 2:
                        B.get(arr.get(1).getPole()).setImageDrawable(arr.get(1).getImg());
                        break;
                    case 3:
                        C.get(arr.get(1).getPole()).setImageDrawable(arr.get(1).getImg());
                        break;
                    }

            }


            private void initializeVariables() {


                dsc1 = R.drawable.disc1;
                dsc2 = R.drawable.disc2;
                dsc3 = R.drawable.disc3;
                dsc4 = R.drawable.disc4;
                dsc5 = R.drawable.disc5;
                dsc6 = R.drawable.disc6;
                dsc7 = R.drawable.disc7;
                dsc8 = R.drawable.disc8;
                pole = R.drawable.pole;

                A1= (ImageView) mActivity.findViewById(R.id.A1);
                A2= (ImageView) mActivity.findViewById(R.id.A2);
                A3= (ImageView) mActivity.findViewById(R.id.A3);
                A4= (ImageView) mActivity.findViewById(R.id.A4);
                A5= (ImageView) mActivity.findViewById(R.id.A5);
                A6= (ImageView) mActivity.findViewById(R.id.A6);
                A7= (ImageView) mActivity.findViewById(R.id.A7);
                A8= (ImageView) mActivity.findViewById(R.id.A8);
                B1= (ImageView) mActivity.findViewById(R.id.B1);
                B2= (ImageView) mActivity.findViewById(R.id.B2);
                B3= (ImageView) mActivity.findViewById(R.id.B3);
                B4= (ImageView) mActivity.findViewById(R.id.B4);
                B5= (ImageView) mActivity.findViewById(R.id.B5);
                B6= (ImageView) mActivity.findViewById(R.id.B6);
                B7= (ImageView) mActivity.findViewById(R.id.B7);
                B8= (ImageView) mActivity.findViewById(R.id.B8);
                C1= (ImageView) mActivity.findViewById(R.id.C1);
                C2= (ImageView) mActivity.findViewById(R.id.C2);
                C3= (ImageView) mActivity.findViewById(R.id.C3);
                C4= (ImageView) mActivity.findViewById(R.id.C4);
                C5= (ImageView) mActivity.findViewById(R.id.C5);
                C6= (ImageView) mActivity.findViewById(R.id.C6);
                C7= (ImageView) mActivity.findViewById(R.id.C7);
                C8= (ImageView) mActivity.findViewById(R.id.C8);

                A = new ArrayList<ImageView>(asList(A1, A2, A3, A4, A5, A6, A7, A8));
                B = new ArrayList<ImageView>(asList(B1, B2, B3, B4, B5, B6, B7, B8));
                C = new ArrayList<ImageView>(asList(C1, C2, C3, C4, C5, C6, C7, C8));
            }
    }

I'm calling it from main activity like this:

Async async = new Async(MainActivity.this);
async.execute(from,to); 

Answer 1

Your problem is

switch (arr.get(0).getPoleNumber()) 

in onPostExecute() because arr is NULL .

in doInBackground() the code line ArrayList<Result> arr = new ArrayList<Result>(); should be arr = new ArrayList<Result>();

doInBackground() should be something like,

 @Override
 protected Integer  doInBackground(Result... params) {
     // doubt on this method, it should be in onPreExecute()
     initializeVariables();
     mResources =  mActivity.getResources();
     arr = new ArrayList<Result>();
     arr.add(params[0]);
     arr.add(params[1]);

     return 1;
    }

Also I have doubt over initializeVariables() as you are getting resources using Activity context it should in Application UI thread. not in worker thread like doInbackground()