Abhishek Raj Abhishek Raj - 8 days ago 5
Android Question

Same data is set on each position in RecyclerView when adapter is notified for data change after fetching data from JSON

I'm fetching data from a database and getting JSON correctly. Also, when I set adapter on the RecyclerView, everything seems to work fine except that same data is set on each position, however I get the complete ArrayList with 20 different values. I don't know where I'm messing up with notifyDatasetChanged as it's the first time I'm using the RecyclerView.

I'm using a fragment inside an activity and here in the codes, I've used Log statements(I used "############" instead of LOG_TAG, though) which tells me that complete arraylist of 20 movie details is available when the onBindViewHolder is called.

Here are the codes:

DefaultMovieFragment.java

public class DefaultMovieFragment extends Fragment implements LoaderManager.LoaderCallbacks<ArrayList<Movie>> {

private static final int DEFAULT_MOVIE_LOADER_ID = 1;
ArrayList<Movie> movies;
DefaultMovieAdapter mAdapter;
RecyclerView mRecyclerView;

public DefaultMovieFragment() {
// Required empty public constructor
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Log.v("############", "onCreateView called");
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_default_movie, container, false);
Movie movie = new Movie("ram", 2, "path");
if (savedInstanceState==null){
movies = new ArrayList<>();
}

//First of all check if network is connected or not then only start the loader
ConnectivityManager connMgr = (ConnectivityManager)
getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
if (networkInfo != null && networkInfo.isConnected()) {

/* fetch data. Get a reference to the LoaderManager, in order to interact with loaders. */
startLoaderManager();
Log.v("############", "startLoaderManager called");
}

// Lookup the recyclerview in activity layout
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerViewMovies);

// Create mAdapter passing in the sample user data
mAdapter = new DefaultMovieAdapter(getActivity(), movies);
// Attach the mAdapter to the recyclerview to populate items
mRecyclerView.setAdapter(mAdapter);

// First param is number of columns and second param is orientation i.e Vertical or Horizontal
final StaggeredGridLayoutManager gridLayoutManager =
new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);
// Attach the layout manager to the recycler view
mRecyclerView.setLayoutManager(gridLayoutManager);
// That's all!

return rootView;
}

private void startLoaderManager() {
LoaderManager loaderManager = getLoaderManager();
loaderManager.initLoader(DEFAULT_MOVIE_LOADER_ID, null, this);
Log.v("############", "startLoaderManager finished");
}


@Override
public Loader<ArrayList<Movie>> onCreateLoader(int id, Bundle args) {
Log.v("############", "onCreateLoader called");
Uri baseUri = Uri.parse(UrlsAndConstants.DefaultQuery.DEFAULT_URL);
Log.v("############", "baseUri is "+baseUri.toString());
Uri.Builder uriBuilder = baseUri.buildUpon();
Log.v("############", "uriBuilder is "+uriBuilder.toString());
uriBuilder.appendQueryParameter(API_KEY_PARAM, API_KEY_PARAM_VALUE);
Log.v("############", "uriBuilder.toString() is "+uriBuilder.toString());
String urls = "https://api.themoviedb.org/3/discover/movie?api_key=4182aa25bab27d06344e404f65c4ae76";
return new DefaultMovieLoader(getActivity().getApplicationContext(), urls);
}

@Override
public void onLoadFinished(Loader<ArrayList<Movie>> loader, ArrayList<Movie> movie) {
Log.v("############", "startLoaderManager finished");
if (movie.isEmpty()) {
Log.v("******************", "movies isEmpty");
return;
} else {
Log.v("############", "movies are"+movie);
// Attach the mAdapter to the recyclerview to populate items

mAdapter.setMovieData(movie);
mRecyclerView.setAdapter(mAdapter);
}
}

@Override
public void onLoaderReset(Loader<ArrayList<Movie>> loader) {
Log.v("############", "onLoaderReset called");
}
}


DefaultMovieAdapter.java

public class DefaultMovieAdapter extends RecyclerView.Adapter<DefaultMovieAdapter.ViewHolder>{

// Store a member variable for the movies
private ArrayList<Movie> mDefaultMovie;
// Store the context for easy access
private Context mContext;
private Movie currentMovie;

// Pass in the movies array into the constructor
public DefaultMovieAdapter(Context context, ArrayList<Movie> movies) {
mDefaultMovie = movies;
mContext = context;
}

// Easy access to the context object in the recyclerview
private Context getContext() {
return mContext;
}
/*
Provide a direct reference to each of the views within a data item
Used to cache the views within the item layout for fast access
*/
public static class ViewHolder extends RecyclerView.ViewHolder {
/*
Your holder should contain a member variable
for any view that will be set as you render a row
*/
public final TextView movieTitleTextView;
public final ImageView movieTitleImageView;
/*
We also create a constructor that accepts the entire item row
and does the view lookups to find each subview
*/
public ViewHolder(View itemView) {
/*
Stores the itemView in a public final member variable that can be used
to access the context from any ViewHolder instance.
*/
super(itemView);
movieTitleTextView = (TextView) itemView.findViewById(R.id.grid_item_movie_title);
movieTitleImageView = (ImageView) itemView.findViewById(R.id.grid_item_movie_image);
}
}

@Override
public DefaultMovieAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

View v = LayoutInflater.from(parent.getContext()).
inflate(R.layout.item_movies, parent, false);
return new ViewHolder(v);
}

@Override
public void onBindViewHolder(DefaultMovieAdapter.ViewHolder viewHolder, int position) {
Log.v("############", "onBindViewHolder called");
// Get the data model based on position
currentMovie = mDefaultMovie.get(position);
Log.v("############", "currentMovie called is "+currentMovie.toString());
Log.v("############", "currentMovie's title is "+currentMovie.getMovieTitle().toString());
/*
Set item views based on your views and data model
TextView textView = viewHolder.movieTitleTextView;
*/
viewHolder.movieTitleTextView.setText(currentMovie.getMovieTitle());
Log.v("############", "title is :>>>>>>>>>>>>>>>>>>>>>>>>>>>>>"+currentMovie.getMovieTitle());
//ImageView button = viewHolder.movieTitleImageView;
//viewHolder.movieTitleImageView.setImageResource(R.mipmap.ic_launcher);
String url = "https://image.tmdb.org/t/p/w500/"+currentMovie.getMoviePosterPath().toString();
Log.v("############", "poster path is :>>>>>>>>>>>>>>>>>>>>>>>>>>>>>"+currentMovie.getMoviePosterPath().toString());
Picasso.with(getContext())
.load(url)
.placeholder(R.mipmap.ic_launcher)
.into(viewHolder.movieTitleImageView);
}

@Override
public int getItemCount() {
Log.v("############", "getItemCount called with size "+ mDefaultMovie.size());
return mDefaultMovie.size();
}
public void setMovieData(ArrayList<Movie> weatherData) {
Log.v("############", "setMovieData Called");
mDefaultMovie = weatherData;
Log.v("############", "mDefaultMovie is "+mDefaultMovie);
notifyDataSetChanged();
Log.v("############", "notifyDataSetChanged Finished");
}
}


DefaultMovieLoader.java

public class DefaultMovieLoader extends AsyncTaskLoader {

/**
* Query URL
*/
private String mUrl;

/**
* Constructs a new {@link DefaultMovieLoader}.
*
* @param context of the activity
* @param url to load data from
*/
public DefaultMovieLoader(Context context, String url) {
super(context);
mUrl = url;
Log.v("############", "url is "+mUrl);
}

@Override
protected void onStartLoading() {
forceLoad();
Log.v("############", "onStartLoading called");
}

/**
* This is on a background thread.
*/
@Override
public ArrayList<Movie> loadInBackground() {
if (mUrl == null) {
return null;
}

// Perform the network request, parse the response, and extract a list of news.
ArrayList<Movie> movies = QueryUtils.fetchMovieData(mUrl);
Log.v("############", "loadInBackground called");
return movies;
}
}


Note: The code is available also in a Gist here: https://gist.github.com/rajtheinnovator/4ae0ab873129eff84db68d5645ac64d8

Thanks a lot, but actually I'm stuck in this position matter for last 2 days. So any input from you is highly appreciable.

Edit:

public class QueryUtils {
private static String movieTitle;
private static int movieId;
private static String moviePosterPath;

/**
* Create a private constructor because no one should ever create a {@link QueryUtils} object.
* This class is only meant to hold static variables and methods, which can be accessed
* directly from the class name QueryUtils (and an object instance of QueryUtils is not needed).
*/
private QueryUtils() {
}

/**
* Query the GUARDIAN dataset and return an {@link Movie} ArrayList to represent a single Movie.
*/
public static ArrayList<Movie> fetchMovieData(String requestUrl) {
Log.v("############", "fetchMovieData called");
// Create URL object
URL url = createUrl(requestUrl);

// Perform HTTP request to the URL and receive a JSON response back
String jsonResponse = null;
try {
jsonResponse = makeHttpRequest(url);
} catch (IOException e) {
//handle exception
}

// Extract relevant fields from the JSON response and create an {@link Event} object
ArrayList<Movie> movies = extractFeatureFromJson(jsonResponse);

// Return the {@link Event}
return movies;
}

/**
* Returns new URL object from the given string URL.
*/
private static URL createUrl(String stringUrl) {
URL url = null;
try {
url = new URL(stringUrl);
} catch (MalformedURLException e) {
//handle exception
}
return url;
}

/**
* Make an HTTP request to the given URL and return a String as the response.
*/
private static String makeHttpRequest(URL url) throws IOException {
Log.v("############", "makeHttpRequest called");
String jsonResponse = "";

// If the URL is null, then return early.
if (url == null) {
return jsonResponse;
}

HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setReadTimeout(10000 /* milliseconds */);
urlConnection.setConnectTimeout(15000 /* milliseconds */);
urlConnection.setRequestMethod("GET");
urlConnection.connect();

/*
If the request was successful (response code 200),
then read the input stream and parse the response.
*/
if (urlConnection.getResponseCode() == 200) {
inputStream = urlConnection.getInputStream();
jsonResponse = readFromStream(inputStream);
} else {
//handle exception
}
} catch (IOException e) {
//handle exception
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (inputStream != null) {
inputStream.close();
}
}
return jsonResponse;
}

/**
* Convert the {@link InputStream} into a String which contains the
* whole JSON response from the server.
*/
private static String readFromStream(InputStream inputStream) throws IOException {
StringBuilder output = new StringBuilder();
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
while (line != null) {
output.append(line);
line = reader.readLine();
}
}
return output.toString();
}

/**
* Return a list of {@link Movie} objects that has been built up from
* parsing a JSON response.
*/
public static ArrayList<Movie> extractFeatureFromJson(String jsonResponse) {
Log.v("############", "extractFeatureFromJson called");
Log.v("############", "jsonResponse"+jsonResponse);

// Create an empty ArrayList that we can start adding movies to
ArrayList<Movie> movies = new ArrayList<Movie>();

/*
Try to parse the received jsonResponse. If there's a problem with the way the JSON
is formatted, a JSONException exception object will be thrown. Catch the exception
so the app doesn't crash, and handle exception.
*/
try {
// Parse the jsonResponse string
JSONObject movie_json_response = new JSONObject(jsonResponse);
Log.v("############", "JSONObject is: " + movie_json_response.toString());
if (movie_json_response.has("results")) {
JSONArray resultsArray = movie_json_response.getJSONArray("results");
if (resultsArray.length() > 0) {
for (int i = 0; i < resultsArray.length(); i++) {
JSONObject movieDetail = resultsArray.getJSONObject(0);
if (movieDetail.has("title")) {
movieTitle = movieDetail.getString("title");
}
if (movieDetail.has("id")) {
movieId = movieDetail.getInt("id");
}
if (movieDetail.has("poster_path")) {
moviePosterPath = movieDetail.getString("poster_path");
}
Log.v("############", " title is "+movies + "############ id is"+movieId+" ############ poster path is "+moviePosterPath);
movies.add(new Movie(movieTitle, movieId, moviePosterPath));
}
}
}
} catch (JSONException e) {
//handle exception
}
Log.v("############", "Movies returned is: " + movies.toString());
// Return the list of movies
return movies;
}
}


Update:

StackTrace here in the gist: https://gist.github.com/rajtheinnovator/4ae0ab873129eff84db68d5645ac64d8#file-stacktrace-xml

Answer

Update your parser logic which exist in QueryUtils.

for (int i = 0; i < resultsArray.length(); i++) {
 Change zeroth index to i
//JSONObject movieDetail =  resultsArray.getJSONObject(0);

And I suggest you create a Local variable currentMovie instead of Global variable.

@Override
public void onBindViewHolder(DefaultMovieAdapter.ViewHolder viewHolder, int position) {
// Use Local variable
Movie currentMovie = mDefaultMovie.get(position);
}
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