Getting error while executing AsyncTask in Android App

Issue

I am Getting an error java.lang.RuntimeException: An error occurred while executing doInBackground() while executing

here is my doInBackground() method

 @Override
    protected String doInBackground(String... strings) {


            AlertDialog.Builder rewardedAdvert = new AlertDialog.Builder(PlayGame.this);
            View rView = getLayoutInflater().inflate(R.layout.rewardedads, null);
            homeButton = (Button) rView.findViewById(R.id.homebutton);


            homeButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {

                    gameOver();
                }
            });
            rewardedAdvert.setView(rView);

            AlertDialog dialog = rewardedAdvert.create();
          dialog.getWindow().setLayout(700, 700);


        return null;
    }

here is the method where i am calling AsyncTask

  private void wrongAnswer() {
    correctImg.setVisibility(View.INVISIBLE);
    wrongImg.setVisibility(View.VISIBLE);
    ((LightQuiz) this.getApplicationContext()).soundHandler.playWrongSound();
    lives--;
    if (lives == 0) {

       new GameOverRewardedAds().execute();

      //  gameOver();




    }

here is the logcat:

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.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
                                                                            at android.os.Handler.<init>(Handler.java:200)
                                                                            at android.os.Handler.<init>(Handler.java:114)
                                                                            at android.app.Dialog.<init>(Dialog.java:119)
                                                                            at android.app.AlertDialog.<init>(AlertDialog.java:200)
                                                                            at android.app.AlertDialog$Builder.create(AlertDialog.java:1086)
                                                                            at com.awwalsoft.javaplay.PlayGame$GameOverRewardedAds.doInBackground(PlayGame.java:429)
                                                                            at com.awwalsoft.javaplay.PlayGame$GameOverRewardedAds.doInBackground(PlayGame.java:387)
                                                                            at android.os.AsyncTask$2.call(AsyncTask.java:295)
                                                                            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
                                                                            at android.os.AsyncTask$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) 

Solution

Your doInBackground is not executing on the UI thread but on the different thread and you can't touch views created on UI thread from background thread. Also, in your AsyncTask you are not doing anything that needs to be done in the background, so you can move all the stuff to your activity which runs on the UI thread.

Main reason for using AsyncTask is some lengthy job that would freeze your UI if it's done on the main thread. If you are just dealing with your views and performing short tasks then leave it on the main thread.

Answered By - colens