Error while executing an AsyncTask from onPostExecute method of another AsyncTask

Issue

I am trying to develop a Video Streaming Application using Firebase which stores video into Firebase storage and retrieves it from there by parsing it into an URI.

Problem

I am trying to execute an AsyncTask inside onPostExecute of another AsyncTask and receiving this following error:

 java.lang.RuntimeException: An error occurred while executing doInBackground()
        at android.os.AsyncTask$3.done(AsyncTask.java:309)
        at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
        at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
        at java.util.concurrent.FutureTask.run(FutureTask.java:242)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
        at java.lang.Thread.run(Thread.java:818)
     Caused by: java.lang.IllegalStateException
        at android.media.MediaPlayer.getCurrentPosition(Native Method)
        at android.widget.VideoView.getCurrentPosition(VideoView.java:881)
        at com.foodies.mohitgupta.foodyyoucantstsyhungry.KitchenVideoView$ViewProgresss$override.doInBackground(KitchenVideoView.java:186)
        at com.foodies.mohitgupta.foodyyoucantstsyhungry.KitchenVideoView$ViewProgresss$override.access$dispatch(KitchenVideoView.java)
        at com.foodies.mohitgupta.foodyyoucantstsyhungry.KitchenVideoView$ViewProgresss.doInBackground(KitchenVideoView.java:0)
        at com.foodies.mohitgupta.foodyyoucantstsyhungry.KitchenVideoView$ViewProgresss.doInBackground(KitchenVideoView.java:176)
        at android.os.AsyncTask$2.call(AsyncTask.java:295)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)

Here is the first AsyncTask implementation on which onPostExecute() method I tried to execute the second AsyncTask:

    class playy extends AsyncTask<String,Void,Uri>
    {

        @Override
        protected Uri doInBackground(String... strings) {
            Uri u=Uri.parse(strings[0]);
            return u;
        }

        @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR1)
        @Override
        protected void onPostExecute(Uri uri) {
            super.onPostExecute(uri);
            vvv=new ViewProgresss();
            video.setVideoURI(uri);
            video.setOnInfoListener(new MediaPlayer.OnInfoListener() {
                @Override
                public boolean onInfo(MediaPlayer mp, int what, int extra) {
                    if (what == mp.MEDIA_INFO_VIDEO_RENDERING_START) {
                        pmain.setVisibility(View.GONE);
                        return true;
                   } else if (what == mp.MEDIA_INFO_BUFFERING_START) {
                        pmain.setVisibility(View.VISIBLE);
                        return true;
                    } else if (what == mp.MEDIA_INFO_BUFFERING_END) {
                        pmain.setVisibility(View.INVISIBLE);
                        return true;
                    }
                    return false;
                }
            });
            video.requestFocus();
            video.start();
            isPlaying = true;
            play.setImageResource(R.drawable.ic_media_play);

            new ViewProgresss().execute();
            video.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
                @Override
                public void onPrepared(MediaPlayer mp) {
                    duration = mp.getDuration() / 1000;
                    String durationString = String.format("%02d:%02d", duration / 60, duration % 60);
                    TotalVideo.setText(durationString);
                }
            });

        }
    }

Here is the second AsyncTask details with the onBackPressed() method:

    public class ViewProgresss extends AsyncTask<Void,Integer,Void>
    {

        @Override
        protected Void doInBackground( Void... voids ) {

            do{
                if(isCancelled()){
                    break;}
                    current = video.getCurrentPosition() / 1000;
                    try {
                      publishProgress(current);
                    } catch (Exception e) {
                    }

            }while(pvideo.getProgress()<=100);
            return null;

        }

        @Override
        protected void onProgressUpdate( Integer... values ) {
            super.onProgressUpdate(values);

            try{
                int currentPro=current* 100/duration;
                pvideo.setProgress(currentPro);
                String CurrentTime=String.format("%02d:%02d",values[0]/60,values[0]%60);
                StartVideo.setText(CurrentTime);
            }catch (Exception e)
            {

            }

        }

    }

    @Override
    public void onBackPressed() {
        super.onBackPressed();
        vvv.cancel(true);
        video.stopPlayback();
        isPlaying=false;
        }

Solution

"video.getCurrentPosition()" cannot be executed until the "onPrepared()" method is called, and that's why you get this Exception: the file is not loaded in the MediaPlayer yet.

Answered By - emandt