Endless recyclerview on load more scrolls to start of the list

Question

I have got onload more functionality in my app, but when I reach the end of list new items are loaded but the list automatically scrolls to the start of the list.

This is the onload function:

         recyclerView.addOnScrollListener(new EndlessRecyclerOnScrollListener(mLayoutManager) {
            @Override
            public void onLoadMore(int current_page, int position) {
                // do something...
                Log.d("Yaeye!", "HElloyoyo");
                SuperHeroes superHero = listSuperHeroes.get(position);

                Log.d("we want url", superHero.getImageUrl());
                imgoffset = superHero.getImageUrl();
                // Do something
                getData(0);

            }
        });

Here is the parsing of the data received from the server:

           JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(url,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        //Dismissing progress dialog
                        // loading.dismiss();

                        //calling method to parse json array
                        parseData(response);

                            adapter.notifyDataSetChanged();



                    }

                },

                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                    }
                });



        //Creating request queue
        RequestQueue requestQueue = Volley.newRequestQueue(this);

        //Adding request to the queue
        requestQueue.add(jsonArrayRequest);


    }
    public int z;
    //This method will parse json data
    private int parseData(JSONArray array){
        for(int i = 0; i<array.length(); i++) {
            SuperHeroes superHero = new SuperHeroes();
            CardAdapter car = new CardAdapter();
            JSONObject json = null;
            try {
                json = array.getJSONObject(i);
                superHero.setImageUrl(json.getString(Config.TAG_IMAGE_URL));
                superHero.setProUrl(json.getString("pro_pic"));
                Img =json.getString(Config.TAG_IMAGE_URL);
                superHero.setName(json.getString(Config.TAG_NAME));
                superHero.setRank(json.getInt(Config.TAG_RANK));
                superHero.setstat(false);

                Log.d("test",Img);
                car.setImageUrl(Img);


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

             adapter.notifyItemInserted(listSuperHeroes.size());
                listSuperHeroes.add(superHero);

             //   adapter.notifyDataSetChanged();
                loading=false;
      }

EndlessRecyclerOnScrollListener is taken from here

package com.example.tatson.bila;



        import android.app.ProgressDialog;
        import android.content.ContentValues;
        import android.content.Context;
        import android.content.SharedPreferences;
        import android.media.Image;
        import android.os.AsyncTask;
        import android.os.Bundle;
        import android.support.v7.widget.LinearLayoutManager;
        import android.support.v7.widget.RecyclerView;
        import android.util.Log;
        import android.view.LayoutInflater;
        import android.view.View;
        import android.view.ViewGroup;
        import android.widget.Button;
        import android.widget.ImageButton;
        import android.widget.ImageView;
        import android.widget.TextView;
        import android.widget.Toast;
        import com.example.tatson.bila.Register;

        import com.android.volley.toolbox.ImageLoader;
        import com.android.volley.toolbox.NetworkImageView;

        import org.json.JSONException;
        import org.json.JSONObject;
        import org.w3c.dom.Text;

        import java.io.BufferedReader;
        import java.io.IOException;
        import java.io.InputStreamReader;
        import java.io.OutputStream;
        import java.io.OutputStreamWriter;
        import java.io.UnsupportedEncodingException;
        import java.net.HttpURLConnection;
        import java.net.URL;
        import java.net.URLEncoder;
        import java.util.ArrayList;
        import java.util.HashMap;
        import java.util.List;
        import java.util.Map;

        import javax.net.ssl.HttpsURLConnection;

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


    private String imageUrl;
    private ImageLoader imageLoader,imageLoader1;
    private Context context;
    String Load;
private static ClickListener c;
    public static final String uu = "uu";
    String number;

    public static final String UserNum = "UserNum";
    SharedPreferences sharedPref;

    private String[] pos;
    private int visibleThreshold = 5;
    private int lastVisibleItem, totalItemCount;
    private boolean loading;
    private OnLoadMoreListener onLoadMoreListener;
    // JSON parser class
    JSONParser jsonParser = new JSONParser();
    String url,imgoffset;
    //testing from a real server:
    private static final String LIKE_URL = "**";

    //ids
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_MESSAGE = "message";
    List<SuperHeroes> superHeroes1;
    //List of superHeroes

    List<SuperHeroes> superHeroes;
    private RecyclerView recyclerView;


    public CardAdapter() {
    }

    public CardAdapter(List<SuperHeroes> superHeroes, Context context) {
        super();
        //Getting all the superheroes
        this.superHeroes = superHeroes;
        superHeroes1= superHeroes;
        this.context = context;
        sharedPref  =context.getSharedPreferences(UserNum, 0);
        number =  sharedPref.getString(uu, "");

    }


    public void setImageUrl(String imageUrl) {
        this.imageUrl = imageUrl;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.superheroes_list, parent, false);
        ViewHolder viewHolder = new ViewHolder(v);
        return viewHolder;



    }


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

        SuperHeroes superHero = superHeroes.get(position);
       Log.d("position", String.valueOf(position));
        Log.d("url", superHero.getImageUrl());
        imageLoader = CustomVolleyRequest.getInstance(context).getImageLoader();
        imageLoader.get(superHero.getImageUrl(), ImageLoader.getImageListener(holder.imageView, R.mipmap.ic_launcher, android.R.drawable.ic_dialog_alert));
        imageLoader1 = CustomVolleyRequest.getInstance(context).getImageLoader();
        imageLoader1.get(superHero.getProurl(), ImageLoader.getImageListener(holder.thumbNail, R.mipmap.ic_launcher, android.R.drawable.ic_dialog_alert));

        Log.d("i am ob", "ob");
        holder.imageView.setImageUrl(superHero.getImageUrl(), imageLoader);
        holder.thumbNail.setImageUrl(superHero.getProurl(), imageLoader1);
        holder.textViewName.setText(superHero.getName());
        holder.textViewRank.setText(String.valueOf(superHero.getRank()));

      if(superHero.getstat())
     {
          Log.d("i am g","g");
         Log.d("i am value", String.valueOf(superHero.getstat()));
            holder.like.setImageResource(R.drawable.plike);
        }
       else
       {
          Log.d("i am p","p");
            holder.like.setImageResource(R.drawable.glike);
        }



        // holder.textViewPowers.setText(powers);
        holder.like.setOnClickListener(new View.OnClickListener(){

@Override
            public void onClick(View v) {
                Log.d("i m in like","i m in like");
            if(dudo!=null) {
                Log.d("i m in like1", "i m in like1");
                dudo.onlike(v, position);


            }}        });


    }

public void refresh(List<SuperHeroes> superHeroes){
    Log.d("Refresh","Refresh is called ");
    this.superHeroes=superHeroes;
  //  notifyDataSetChanged();
}

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






        public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
            public NetworkImageView imageView;
          public CircularNetworkImageView thumbNail;
            public TextView textViewName;
            public TextView textViewuserName;
            public TextView textViewRank;
            public ImageButton like;
        public ViewHolder(View itemView) {
            super(itemView);
            imageView = (NetworkImageView) itemView.findViewById(R.id.imageViewHero);
            textViewName = (TextView) itemView.findViewById(R.id.username_row);
            //textViewuserName = (TextView) itemView.findViewById(R.id.username_row);
            textViewRank = (TextView) itemView.findViewById(R.id.textViewRank);
            thumbNail = (CircularNetworkImageView) itemView.findViewById(R.id.thumbnail);
            like = (ImageButton) itemView.findViewById(R.id.button_like);
         //   itemView.setOnClickListener( this);




        }


        @Override
        public void onClick(View v) {
            if (dudo != null) {
                Log.d("i m in like1", "i m in like1");
                dudo.onlike(v, 2);
            }
        }
    }


    class LikeIt extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Dialog
         */
        boolean failure = false;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();

        }

        @Override
        protected String doInBackground(String... args) {
            // TODO Auto-generated method stub
            // Check for success tag

             int success;

            String Imgurl = Load;
            Log.d("request!", number);

          //  try {
                // Building Parameters
                HashMap<String, String> Params = new HashMap<String, String>();
                Params.put("Imgurl", Imgurl);
           Params.put("user", number);


                Log.d("request!", "starting");


                String encodedStr = getEncodedData(Params);

                //Will be used if we want to read some data from server
                BufferedReader reader = null;

                //Connection Handling
                try {
                    //Converting address String to URL
                    URL url = new URL(LIKE_URL);
                    //Opening the connection (Not setting or using CONNECTION_TIMEOUT)
                    HttpURLConnection con = (HttpURLConnection) url.openConnection();

                    //Post Method
                    con.setRequestMethod("POST");
                    //To enable inputting values using POST method
                    //(Basically, after this we can write the dataToSend to the body of POST method)
                    con.setDoOutput(true);
                    OutputStreamWriter writer = new OutputStreamWriter(con.getOutputStream());
                    //Writing dataToSend to outputstreamwriter
                    writer.write(encodedStr);
                    //Sending the data to the server - This much is enough to send data to server
                    //But to read the response of the server, you will have to implement the procedure below
                    writer.flush();

                    //Data Read Procedure - Basically reading the data comming line by line
                    StringBuilder sb = new StringBuilder();
                    reader = new BufferedReader(new InputStreamReader(con.getInputStream()));

                    String line;
                    while((line = reader.readLine()) != null) { //Read till there is something available
                        sb.append(line + "\n");     //Reading and saving line by line - not all at once
                    }
                    line = sb.toString();           //Saving complete data received in string, you can do it differently

                    //Just check to the values received in Logcat
                    Log.i("custom_check","The values :");
                    Log.i("custom_check", line);

                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if(reader != null) {
                        try {
                            reader.close();     //Closing the
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }

                //Same return null, but if you want to return the read string (stored in line)
                //then change the parameters of AsyncTask and return that type, by converting
                //the string - to say JSON or user in your case
                return null;
            }

        }
    private String getEncodedData(Map<String,String> data) {
        StringBuilder sb = new StringBuilder();
        for(String key : data.keySet()) {
            String value = null;
            try {
                value = URLEncoder.encode(data.get(key), "UTF-8");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }

            if(sb.length()>0)
                sb.append("&");

            sb.append(key + "=" + value);
        }
        return sb.toString();
    }

        /**
         * After completing background task Dismiss the progress dialog
         **/
        protected void onPostExecute() {
            // dismiss the dialog once product deleted

            }


private  static ClickListener dudo ;
  public interface ClickListener{
       void onlike(View v,int pos);



    }
    public void setClickListener(ClickListener dudo){
        this.dudo=dudo;
        Log.d("i m in interface","i m in interface");
    }
}

Here is sample of endless scroll https://github.com/lokesht/UdacityPopulerMovie — Lokesh Tiwari, Feb 23 '16 at 08:05

score 0 · Answer 1 · answered Feb 23 '16 at 05:47

0

modify your for loop and try again

for(int i = 0; i<array.length(); i++) {
    SuperHeroes superHero = new SuperHeroes();
    CardAdapter car = new CardAdapter();
    JSONObject json = null;
    try {
        json = array.getJSONObject(i);  
        superHero.setImageUrl(json.getString(Config.TAG_IMAGE_URL));
        superHero.setProUrl(json.getString("pro_pic"));
        Img =json.getString(Config.TAG_IMAGE_URL);
        superHero.setName(json.getString(Config.TAG_NAME));
        superHero.setRank(json.getInt(Config.TAG_RANK));
        superHero.setstat(false);

        Log.d("test",Img);
        car.setImageUrl(Img);
    } catch (JSONException e) {
        e.printStackTrace();
    }    
    listSuperHeroes.add(superHero);
}
loading=false;
adapter.notifyDataSetChanged();
//adapter.notifyItemInserted(listSuperHeroes.size());

My guess is that you are refreshing each time the item is added in the for loop which might be the problem in your case.

answered Feb 23 '16 at 05:47

Vishnu Prabhu

449
1
5
19

i tried this also but still when onload more gets called the list again scrolls to the first element – Tatson Baptista Feb 23 '16 at 06:37
check point number 4 in : http://stackoverflow.com/a/17696214/3035416 .... Are you creating a new list everytime? – Vishnu Prabhu Feb 23 '16 at 06:44
The error is with the refresh method. Use this.superHeroes.addAll(superHeroes); notifyDataSetChanged(); you have to cal notifydatasetchanged method. the error is you are initializing a new array each time your data is loaded in the adapter. Rather you have to set a same arraylist and add data to it. – Vishnu Prabhu Feb 24 '16 at 05:13
the refresh function is never called in this code sample – Tatson Baptista Feb 24 '16 at 05:33

score 0 · Answer 2 · answered Feb 23 '16 at 06:21

private int parseData(JSONArray array){
  //temporary List to store all the new data from the json
  List<SuperHeroes> tempList=new ArrayList<>();
  //get start position to use later
  int startPos=listSuperHeroes.size()-1;
    for(int i = 0; i<array.length(); i++) {
        SuperHeroes superHero = new SuperHeroes();
        CardAdapter car = new CardAdapter();
        JSONObject json = null;
        try {
            json = array.getJSONObject(i);
            superHero.setImageUrl(json.getString(Config.TAG_IMAGE_URL));
            superHero.setProUrl(json.getString("pro_pic"));
            Img =json.getString(Config.TAG_IMAGE_URL);
            superHero.setName(json.getString(Config.TAG_NAME));
            superHero.setRank(json.getInt(Config.TAG_RANK));
            superHero.setstat(false);

            Log.d("test",Img);
            car.setImageUrl(Img);


        } catch (JSONException e) {
            e.printStackTrace();
            //You do not want to add the item incase there is a json exception
            continue;
        }


            tempList.add(superHero);

         //   adapter.notifyDataSetChanged();
            loading=false;
  }
     listSuperHeroes.addAll(tempList)
     adapter.notifyItemRangeInserted(startPos,tempList.size());
}

You want to add all the items and call notifyDatasetChanged() once. If you call the notifyDatasetChanged() at every addition,there is a possibility that you will face a Inconsistency Detected exception soon enough.

RecyclerView has several helper methods to inform changes in the dataset. notifyDatasetChanged() is the one which would refresh the entire dataset which will be an overkill in your scenario.

Consider using the other methods like notifyItemRangeInserted which will add items to the bottom of the list. This has 2 major advantages - Your list does not jump to positions on adding data - The RecyclerView automatically animates the addition(this can be overriden)

You will face issues with the Inconsistency Detected error if your positions/itemcount are incorrect.

In that case you could use notifyDatasetChanged() .

score 0 · Answer 3 · answered Feb 23 '16 at 06:59

Try this,

private int previousTotal = 0;
private boolean loading = true;
private int visibleThreshold = 5;
int firstVisibleItem, visibleItemCount, totalItemCount;

mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
    super.onScrolled(recyclerView, dx, dy);

    visibleItemCount = mRecyclerView.getChildCount();
    totalItemCount = mLayoutManager.getItemCount();
    firstVisibleItem = mLayoutManager.findFirstVisibleItemPosition();

    if (loading) {
        if (totalItemCount > previousTotal) {
            loading = false;
            previousTotal = totalItemCount;
        }
    }
    if (!loading && (totalItemCount - visibleItemCount) 
        <= (firstVisibleItem + visibleThreshold)) {
        // End has been reached

        Log.i("Yaeye!", "end called");

        // Do something

        loading = true;
    }
}
});

LinearLayoutManager mLayoutManager;
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);

i am already using a similar version of this code in a class EndlessRecyclerOnScrollListener but it doesn't work — Tatson Baptista, Feb 23 '16 at 07:40
Add your adapter to the question and also how you initialize the adapter — Droidekas, Feb 23 '16 at 07:41

Endless recyclerview on load more scrolls to start of the list

3 Answers3