How to get and show a value from an AsyncTask?

Issue

I want to get and show a value obtained with an Asynctask but i'm not very familiar with it...

My AsyncTask :

private class loadDetails extends AsyncTask<Void,Void,Void>() {

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

            final Movie details = (Movie) getIntent().getExtras().getSerializable("MOVIE_DETAILS");
            int idMovie = details.getId();

            OkHttpClient client = new OkHttpClient();

            Request request = new Request.Builder()
                    .url("https://api.themoviedb.org/3/movie/" + idMovie + "?api_key=" + API_KEY + "&language=en-US")
                    .build();

            Response response = client.newCall(request).execute();
            JSONObject root = new JSONObject(response.body().string());

            int runtime = root.getInt("runtime");
            Log.i("test", runtime + " min");

            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            //?
        }
    }

My full activity code :

public class MovieDetailActivity extends AppCompatActivity {

    private ImageView backdrop_image, poster;
    private TextView overview, releaseDate, genresList;
    private RatingBar rating;
    private static final String TAG = "MovieDetails";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_movie_detail);
        new loadDetails().execute();

        final Movie details = (Movie) getIntent().getExtras().getSerializable("MOVIE_DETAILS");

        ActionBar actionBar = getSupportActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);
        actionBar.setTitle(details.getTitle());

        backdrop_image = findViewById(R.id.movie_backdrop_image);
        poster = findViewById(R.id.movie_poster);
        title = findViewById(R.id.movie_title);
        releaseDate = findViewById(R.id.movie_release_date);
        rating = (RatingBar) findViewById(R.id.movie_rating_bar);
        overview = findViewById(R.id.movie_overview);
        genresList = findViewById(R.id.movie_genres);

        if (details != null){

            Glide.with(this)
                    .load(IMAGE_BASE_URL + details.getBackdropPath())
                    .apply(RequestOptions.placeholderOf(R.color.colorPrimary))
                    .into(backdrop_image);
            Glide.with(this)
                    .load(IMAGE_BASE_URL + details.getPosterPath())
                    .apply(RequestOptions.placeholderOf(R.color.colorPrimary))
                    .into(poster);

            title.setText(details.getTitle());
            releaseDate.setText(details.getReleaseDate());
            overview.setText(details.getOverview());
            double d = details.getTMDBRating();
            float f = (float) d;
            rating.setRating(f/2);

        }
    }

    private class loadDetails extends AsyncTask<Void,Void,Void>() {

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

            final Movie details = (Movie) getIntent().getExtras().getSerializable("MOVIE_DETAILS");
            int idMovie = details.getId();

            OkHttpClient client = new OkHttpClient();

            Request request = new Request.Builder()
                    .url("https://api.themoviedb.org/3/movie/" + idMovie + "?api_key=" + API_KEY + "&language=en-US")
                    .build();

            Response response = client.newCall(request).execute();
            JSONObject root = new JSONObject(response.body().string());

            int runtime = root.getInt("runtime");
            Log.i("test", runtime + " min");

            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            //?
        }
    }

    @Override
    public boolean onSupportNavigateUp(){
        finish();
        return true;
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.save_menu, menu);
        return true;
    }
}

I want to display the runtime in a TextView.

Solution

private class loadDetails extends AsyncTask<Void,Void,Integer>() {

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

        final Movie details = (Movie) getIntent().getExtras().getSerializable("MOVIE_DETAILS");
        int idMovie = details.getId();

        OkHttpClient client = new OkHttpClient();

        Request request = new Request.Builder()
                .url("https://api.themoviedb.org/3/movie/" + idMovie + "?api_key=" + API_KEY + "&language=en-US")
                .build();

        Response response = client.newCall(request).execute();
        JSONObject root = new JSONObject(response.body().string());

        int runtime = root.getInt("runtime");
        Log.i("test", runtime + " min");

        return runtime;
    }

    @Override
    protected void onPostExecute(Integer anInt) {
        yourTextView.setText("yourInt = " + anInt);
    }
}

that should do the trick.. I didn't compile it but generally the 3rd generics parameter of the async task is the return type from doInBackround() to onPostExecute() and there you can touch your views.

Answered By - Alon Aviram