How to stop Handler inside an asynctask

Question

I have the following asynctask, which contains an Handler inside it, but when I leave Activity I close the async but sometimes Handler keeps calling the async after it’s closed. No crash in the application but keeps sending logs as if it was giving error, follows below async

public class PostImageAsyncTask extends AsyncTask<Object, Object, PutObjectResult> {

    public PostImageAsyncTask() {
        super();

    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // before making http calls

    }

    @Override
    protected PutObjectResult doInBackground(Object... params) {
        try {
            return amazonS3Client.putObject(por);
        } catch (AmazonServiceException e) {
            return null;
        } catch (AmazonClientException e) {
            return null;
        }

    }

    @Override
    protected void onPostExecute(PutObjectResult result) {
        if (!isCancelled()) {
            if (result != null) {
                showAndHideLoad(false);
                if(step == 0) {
                    picture = new Picture(amazonUrl, null);
                } else if(step == 1) {
                    documentIDs = new DocumentIDs(amazonUrl,null);
                } else if( step == 2){
                    documentIDs.setBackURL(amazonUrl);
                }

                if ((snackbar != null && snackbar.isShown())) {
                    snackbar.dismiss();
                }
                send_continue();
            } else {

                if (RECONECT_TIME_DELAY < MAX_TIME_DELAY) {
                    if ((snackbar == null || !snackbar.isShown())) {
                        isClicked=false;
                        snackbar = Snackbar.make(coordinatorLayoutView, getString(R.string.snackbar_internet_fail), Snackbar.LENGTH_INDEFINITE);
                        View sbView = snackbar.getView();
                        TextView textView = (TextView) sbView.findViewById(android.support.design.R.id.snackbar_text);
                        textView.setTextColor(Color.WHITE);
                        snackbar.setActionTextColor(Color.RED);
                        snackbar.setAction("Cancelar", new View.OnClickListener() {
                            @Override
                            public void onClick(View view) {
                                //
                            }
                        });
                        snackbar.show();
                    }
                    handler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            RECONECT_TIME_DELAY = RECONECT_TIME_DELAY * 2;
                            postImageAsyncTask.cancel(true);
                            postImageAsyncTask = new PostImageAsyncTask();
                            postImageAsyncTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
                        }
                    }, RECONECT_TIME_DELAY);
                }
            }
        } else {
            postImageAsyncTask.cancel(true);
        }
    }
}

Answer 1

As AsyncTasks are not made to match with Handler. You can do what you want (update screen elements each time an error occurs while connecting to Amazon) with only one AsyncTask, without needing a Handler for that reason.

AsyncTasks allow updating the screen in the middle of executing an asynchronous task, simply calling the method publishProgress().

In the method doInBackground() make a loop that tries to connect to Amazon a certain number of times. Each time the connection fails, call the method publishProgress(). This will result in the method AsyncTask.onProgressUpdate() be called, and within it you can update the screen as desired.

Leave the method onPostExecute() for the situation where the connection was successful.