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How to use notifydatasgetanged in recyclerview gridlayout

I am new to android and trying to update the application gridlayoutin the popular films of the popular film project nodacity nanodegree.

I download data using AsyncTaskand analyzing data, updating recyclerviewand installation adapter in onPostExecute.

This is my AsyncTask class

private class getJson extends AsyncTask<String, Void, String>{

    @Override
    protected String doInBackground(String... strings) {
        String result = "";
        URL url;
        HttpURLConnection httpURLConnection = null;


        try {
            url = new URL(strings[0]);

            httpURLConnection = (HttpURLConnection) url.openConnection();

            InputStream in = httpURLConnection.getInputStream();

            InputStreamReader reader = new InputStreamReader(in);

            int data = reader.read();

            while ( data != -1 ){
                  char current  = (char) data;

                  result += current;

                  data = reader.read();
            }

        } catch (java.io.IOException e) {
            e.printStackTrace();
        }

        return result;
    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);

        jsonString = s;

        Log.i("result", jsonString);

        JSONObject jsonObject = null;

        if(!list.isEmpty())
          list.clear();
        try {

            jsonObject = new JSONObject(jsonString);

            JSONArray jsonArray = jsonObject.getJSONArray("results");

            for( int i = 0; i < jsonArray.length() && i < 10; i++ ){

                JSONObject currObject = jsonArray.getJSONObject(i);

                String posterurl = preUrl + currObject.getString("backdrop_path");

                Log.i("poster", posterurl);

                String url =  preUrl + currObject.getString("poster_path");

                String overview = currObject.getString("overview");

                String title = currObject.getString("original_title");

                String release_date = (currObject.getString("release_date"));

                String votes = (currObject.getString("vote_average"));

                list.add(new MovieDetails(url,overview, title, release_date, votes, posterurl));
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }



    }
}

This is my adapter class.

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

    ArrayList<MovieDetails> data;
    Context context;

    public MainRecyclerViewAdapter(Context context, ArrayList<MovieDetails> data ){
         this.data = data;
         this.context = context;
    }
    @Override
    public MainRecyclerViewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.grid_item, parent, false);

        MainRecyclerViewAdapter.ViewHolder viewHolder = new MainRecyclerViewAdapter.ViewHolder(v);

        return viewHolder;
    }

    @Override
    public void onBindViewHolder(MainRecyclerViewAdapter.ViewHolder holder, int position) {

        Picasso.with(context).load(data.get(position).getImageUrl()).into(holder.movie_thumbnail);
        //holder.movie_thumbnail.setImageResource(R.mipmap.ic_launcher);


    }

    @Override
    public int getItemCount() {
       return data.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{

        ImageView movie_thumbnail;

        private Context context;

        @Override
        public void onClick(View view) {
            Toast.makeText(context,data.get(getPosition()).getTitle(),Toast.LENGTH_LONG).show();
            Intent intent = new Intent(context, DetailsActivity.class);
            Bundle bundle = new Bundle();
            bundle.putSerializable("list", (Serializable) data);
            intent.putExtras(bundle);
            intent.putExtra("index", getAdapterPosition());

            context.startActivity(intent);
        }

        public ViewHolder(View itemView) {
            super(itemView);
            context = itemView.getContext();
            itemView.setOnClickListener(this);
            movie_thumbnail = (ImageView) itemView.findViewById(R.id.movies_item_thumbnail);
        }
    }
}

This is how I handle sorting based on vote or popularity

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    getJson gJson = new getJson();
    switch (item.getItemId()){
        case R.id.rating :
            gJson.execute(top_rated);
            return true;
        case R.id.popularity : gJson.execute(popular);
            return true;
        default: return super.onOptionsItemSelected(item);

    }

}

onCreate

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar myToolbar = (Toolbar) findViewById(R.id.main_toolbar);
    setSupportActionBar(myToolbar);

    getJson getJson = new getJson();
    getJson.execute(popular);

    recyclerView = (RecyclerView)findViewById(R.id.main_recyclerview);

    recyclerView.setHasFixedSize(true);
    layoutManager = new GridLayoutManager(MainActivity.this,2);
    recyclerView.setLayoutManager(layoutManager);

    adapter = new MainRecyclerViewAdapter(MainActivity.this, list);
    recyclerView.setAdapter(adapter);

}

I decided to use it notifydatasetchanged(), but I cannot figure out where to use it.

Also, please tell me how best to handle sorting.

This is what I did:

  • I moved the adapter instance and adapter settings to onCreate

  • call notfiydatasetchanged()inonPostexeute()

  • , AsyncTask, arraylist , . list.clear() json onPostexecute()

+4
5

,

    private List<Movie> movieList = new ArrayList<>();
    private RecyclerView recyclerView;
    private MoviesAdapter mAdapter;

onCreate

1.

recyclerView = (RecyclerView) findViewById(R.id.recycler_view);

2.

mAdapter = new MoviesAdapter(movieList);

3. .

        RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getApplicationContext());
        recyclerView.setLayoutManager(mLayoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());

4. recycleView

recyclerView.setAdapter(mAdapter);

5. .

setMyData();

setMyData

1. - ..

2.

movieList.add(movie); // i have not added the lines where i add data to my movie list think it has 10 elements now

3.

mAdapter.notifyDataSetChanged();

, , setMyData();, .

?

, ,

: async , setMyData()? .           , !!! ,    layoutManager = new GridLayoutManager(MainActivity.this,2);

ah ha , async... DataSet onPostExecute, ( , ..) , tan ta tan!! asyncTask 10 .. , , .. , !

p.s LayoutManager setMyData(), onCreate

+1

http- retrofit. , notifydatasetchanged();

void sort(String sortBy) {
    // your sort
    notifydatasetchanged();
}

, adapter, .

+1

adapter onCreate .

    adapter = new MainRecyclerViewAdapter(MainActivity.this, list);
    recyclerView.setAdapter(adapter);

.

notifydatasetchanged() onPostExecute() AsyncTask ( ), adapter .

+1

, :

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView = (RecyclerView)findViewById(R.id.main_recyclerview);
        layoutManager = new GridLayoutManager(MainActivity.this, 2);
        recyclerView.setLayoutManager(layoutManager);

        adapter = new MainRecyclerViewAdapter(MainActivity.this, list);
        recyclerView.setAdapter(adapter);
    }

   private class getJson extends AsyncTask<String, Void, String>{

    @Override
    protected String doInBackground(String... strings) {
        String result = "";
        URL url;
        HttpURLConnection httpURLConnection = null;

        try {
            url = new URL(strings[0]);

            httpURLConnection = (HttpURLConnection) url.openConnection();

            InputStream in = httpURLConnection.getInputStream();

            InputStreamReader reader = new InputStreamReader(in);

            int data = reader.read();

            while ( data != -1 ){
                  char current  = (char) data;

                  result += current;

                  data = reader.read();
            }

        } catch (java.io.IOException e) {
            e.printStackTrace();
        }

        return result;
    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);

        jsonString = s;

        Log.i("result", jsonString);

        JSONObject jsonObject = null;
        try {

            jsonObject = new JSONObject(jsonString);

            JSONArray jsonArray = jsonObject.getJSONArray("results");

            for( int i = 0; i < jsonArray.length() && i < 10; i++ ){

                JSONObject currObject = jsonArray.getJSONObject(i);

                String posterurl = preUrl + currObject.getString("backdrop_path");

                Log.i("poster", posterurl);

                String url =  preUrl + currObject.getString("poster_path");

                String overview = currObject.getString("overview");

                String title = currObject.getString("original_title");

                String release_date = (currObject.getString("release_date"));

                String votes = (currObject.getString("vote_average"));

                list.add(new MovieDetails(url,overview, title, release_date, votes, posterurl));
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }

        adapter.notifyDataSetChanged();

    }
}

, , .

+1

To download movies from a remote server is used AsyncTask. After downloading and parsing is complete, you create an adapter and install it inRecyclerView

According to your implementation, there is no need to call notifyDataSetChanged()in postExecute ()

The above approach has one drawback: you create a new adapter instance each time it executes AsyncTask.

Try something below.

 Activity {

    ArrayList<MovieDetails> data;
    MainRecyclerViewAdapter adapter

    onCreate() {

        recyclerView = (RecyclerView)findViewById(R.id.main_recyclerview);

        recyclerView.setHasFixedSize(true);
        layoutManager = new GridLayoutManager(MainActivity.this,2);
        recyclerView.setLayoutManager(layoutManager);


        adapter = new MainRecyclerViewAdapter(MainActivity.this);
        recyclerView.setAdapter(adapter);
    }


    AsyncTask {
        /.....

        onPostExecute{

            // Download completed
            adapter.notifyDataSetChanged()
        }
    }

    MainRecyclerViewAdapter {

        //...
        ViewHolder {
            //...
        }
    }
}
+1
source

Source: https://habr.com/ru/post/1664705/

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