Recyclerview not call any Adapter method :onCreateViewHolder,onBindViewHolder,

Question

my RecyclerView do not call onCreateViewHolder, onBindViewHolder, therefore, does not appear nothing in recyclerview. I put logs for debugging, and no log is shown. What can be?

My adapter:

public class CommentListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{ private static final int EMPTY_VIEW = 10 ; private ArrayList<comment> mItems; Boolean firstTime = true; private Typeface mTf = null; Context mContext; public CommentListAdapter(Context context,ArrayList<comment> items){     Log.e("Adapter", "constructor Called");     this.mItems = items;     mContext = context; } public class EmptyViewHolder extends RecyclerView.ViewHolder {     public EmptyViewHolder(View itemView) {         super(itemView);     } } public class ViewHolder extends RecyclerView.ViewHolder{     TextView mAuthorName;     TextView mMessage;     NetworkImageView mThumbnail;     public ViewHolder(View itemView) {         super(itemView);         mAuthorName = (TextView)itemView.findViewById(R.id.author_name);         mMessage = (TextView)itemView.findViewById(R.id.message);         mThumbnail = (NetworkImageView)itemView.findViewById(R.id.author_avatar);     }  }  public void add(comment item, int position) {     mItems.add(position, item);     notifyItemInserted(position); }  public void remove(comment item) {     int position = mItems.indexOf(item);     mItems.remove(position);     notifyItemRemoved(position); } @Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType){     Log.e("Adapter", "onCreateViewHolder Called");     View v;     if(firstTime){         mTf = BBcTypeFace.getTypeFace(parent.getContext().getApplicationContext(),"font/bbc.ttf");         firstTime = false;     }     if( viewType == EMPTY_VIEW){         v = LayoutInflater.from(parent.getContext())                 .inflate(R.layout.comment_empty_row,parent,false);         EmptyViewHolder evh = new EmptyViewHolder(v);         return evh;     }else {         v = LayoutInflater.from(parent.getContext())                 .inflate(R.layout.comment_row, parent, false);         ViewHolder vh = new ViewHolder(v);         return vh;     } } @Override public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {     Log.e("Adapter", "onBindViewHolder Called");     if(viewHolder instanceof ViewHolder) {         ViewHolder holder = (ViewHolder)viewHolder;         comment c = mItems.get(position);         Log.e("Adapter", "Comment is\n: " + c.toString());         final ViewHolder finalHolder = holder;         ImageRequest request = new ImageRequest(c.author_img_link, new Response.Listener<Bitmap>() {             @Override             public void onResponse(Bitmap bitmap) {                 if (bitmap != null) {                     finalHolder.mThumbnail.setImageBitmap(bitmap);                 }             }         }, 0, 0, null,                 new Response.ErrorListener() {                     @Override                     public void onErrorResponse(VolleyError volleyError) {                         VolleyLog.e("ImageLoader", volleyError.getMessage());                         VolleyLog.e("ImageLoader", volleyError.getStackTrace());                     }                 });         GetVideoInfo.getInstance(mContext.getApplicationContext()).addToRequestQueue(request);         holder.mAuthorName.setText(c.author_name);         holder.mMessage.setText(c.Message);         holder.mMessage.setTypeface(mTf);         holder.mAuthorName.setTypeface(mTf);     } } @Override public int getItemCount() {     Log.e("Adapter", "getItemCount() Called");     return (mItems.size() > 0 ? mItems.size() : 1); } @Override public int getItemViewType(int position) {     Log.e("Adapter", "getItemViewType() Called");     if (mItems.size() == 0) {         return EMPTY_VIEW;     }     return super.getItemViewType(position); }} 

I will use public void add(comment item, int position){...} to add item in RecyclerView.

in Fragment :

private RecyclerView mRecyclerView; private CommentListAdapter mAdapter; private LayoutManager mLayoutManager;  @Override public View onCreateView(LayoutInflater inflater, ViewGroup container,                          Bundle savedInstanceState) {     View rootView = inflater.inflate(R.layout.fragment_item_detail, container, false); ....      mLayoutManager = new LinearLayoutManager(getActivity());     mAdapter = new CommentListAdapter(getActivity(),new ArrayList<comment>());     mRecyclerView = (RecyclerView)rootView.findViewById(R.id.comment_list);     mRecyclerView.setHasFixedSize(true);     mRecyclerView.setLayoutManager(mLayoutManager);     mRecyclerView.setAdapter(mAdapter);     mRecyclerView.setItemAnimator(new DefaultItemAnimator());      makeJsonObjectRequest(mItem.url);     return rootView; } 

XML Files :

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:id="@+id/scrollView"     android:background="@android:color/white"     android:layout_alignParentLeft="true"     android:layout_alignParentStart="true"      android:layout_alignParentBottom="true">      ....         <RelativeLayout             xmlns:android="http://schemas.android.com/apk/res/android"             android:layout_width="match_parent"             android:layout_height="match_parent"> .....              <android.support.v7.widget.RecyclerView                 android:id="@+id/comment_list"                 android:layout_width="match_parent"                 android:layout_height="match_parent">              </android.support.v7.widget.RecyclerView> ....         </RelativeLayout>     .... </ScrollView> 

comment_row xml file :

<?xml version="1.0" encoding="utf-8"?> <LinearLayout     android:orientation="horizontal"     xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="right" android:background="@android:color/darker_gray">  <LinearLayout         android:orientation="vertical"         android:layout_width="wrap_content"         android:layout_height="wrap_content"     android:gravity="right">          <TextView             android:layout_width="match_parent"             android:layout_height="wrap_content"             android:textAppearance="?android:attr/textAppearanceMedium"             android:id="@+id/author_name"             android:layout_alignParentTop="true"             android:layout_toLeftOf="@+id/author_avatar"             android:layout_toStartOf="@+id/author_avatar"             android:gravity="right" />          <TextView             android:layout_width="match_parent"             android:layout_height="wrap_content"             android:id="@+id/message"             android:layout_below="@+id/author_name"             android:layout_toLeftOf="@+id/author_avatar"             android:layout_toStartOf="@+id/author_avatar"             android:gravity="right" />         </LinearLayout>  <com.android.volley.toolbox.NetworkImageView     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:id="@+id/author_avatar"     android:layout_alignParentTop="true"     android:layout_alignParentRight="true"     android:layout_alignParentEnd="true"     android:minHeight="150dp"     android:minWidth="150dp" /></LinearLayout> 

I will add item to RecyclerView with this code :

JsonObjectRequest jsonObjReqComment = new              JsonObjectRequest(Request.Method.GET,urlJsonObj+"#comment", null,                      new Response.Listener<JSONObject>() {                          @Override                          public void onResponse(JSONObject response) {                              try {                                  JSONArray res = response.getJSONArray("response");                                  //Log.e("Comment","Count:"+response.toString());                                  //Log.e("Comment","Count:"+res.length());                                  for (int i = 0; i < res.length(); i++) {                                      JSONObject thread = res.getJSONObject(i);                                      JSONObject author_json = thread.getJSONObject("author");                                      int dislikes = thread.getInt("dislikes");                                      int likes = thread.getInt("likes");                                      String Message = thread.getString("message");                                      //get Author info                                      String author_img_link = author_json.getJSONObject("avatar").getString("permalink");                                      String author_name = author_json.getString("name");                                      comment c = new comment(dislikes,likes,Message,author_img_link,author_name);                                      //Log.e("Comment",c.toString());                                      //commentsList.add(c);                                      mAdapter.add(c,0);                                  }                               } catch (JSONException e) {                                  Log.e("OnResponse","Error JSON");                                  e.printStackTrace();                              } catch (Exception e){                                  Log.e("OnResponse","Error Exception");                                  e.printStackTrace();                              }                            }                      }                      , new Response.ErrorListener() {                  @Override                  public void onErrorResponse(VolleyError error) {                      VolleyLog.d("vOLLEY", "Error: " + error.getMessage());                      // hide the progress dialog                   }              }              ){                  @Override                  public Map<String, String> getHeaders(){                      Map<String, String> headers = new HashMap<String, String>();                      headers.put("User-agent", "Comment");                      return headers;                  }              }; 

Answer 1

Other than @SanatiSharif's and @sohrab's answer, you have to follow below mandatory step.

Make sure you call setLayoutManager, something like below.

recyclerView.setLayoutManager(new LinearLayoutManager(getContext())); 

before setting adapter into recyclerView, otherwise it is not going to work. You can customize it if you need. this link will give you some idea of how LayoutManager works.