RecyclerView is always blank in activity

Question

When I run my application, the RecyclerView is always shown blank in the activity. I did code with the normal RecyclerView as well firebaseRecyclerOptions helps with FirebaseAdapter, but lists not showing any data. The data is available on both Realtime Database and Cloud FireStore, but I don't get any data in RecyclerView.

Adapter class

public class FeedsAdapter  extends FirestoreRecyclerAdapter <Fmodel,FeedsAdapter.myFeedViewHolder> {

    public FeedsAdapter(@NonNull FirestoreRecyclerOptions <Fmodel> options) {
        super ( options );
    }

    @Override
    protected void onBindViewHolder(@NonNull myFeedViewHolder holder, int position, @NonNull Fmodel model) {
        holder.name.setText ( model.getFname () );
        holder.mobile.setText ( model.getFmobile () );
        holder.address.setText ( model.getFaddress ());
        holder.message.setText ( model.getFmessage ());
    }
    @NonNull
    @Override
    public myFeedViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from ( parent.getContext () ).inflate ( R.layout.feedbacks,parent,false );

        return new myFeedViewHolder ( view );
    }

    class myFeedViewHolder extends RecyclerView.ViewHolder{

        TextView name,mobile,address,message;

        public myFeedViewHolder(@NonNull View itemView) {
            super ( itemView );
            name = itemView.findViewById ( R.id.name );
            mobile = itemView.findViewById ( R.id.mobile );
            address = itemView.findViewById ( R.id.address );
            message = itemView.findViewById ( R.id.messege );
        }
    }
}

Activity.xml

 public class FeedsActivity extends AppCompatActivity {

    private FirebaseFirestore firebaseFirestore = FirebaseFirestore.getInstance (  );
    private CollectionReference collectionReference = firebaseFirestore.collection ( "FeedBacks" );
    private  FeedsAdapter feedsAdapter;

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

        setUpRecyclerView();
  }
    
private void setUpRecyclerView() {
        Query query = collectionReference.orderBy ( "Fname", Query.Direction.ASCENDING );
       FirestoreRecyclerOptions <Fmodel> options = new FirestoreRecyclerOptions.Builder<Fmodel>().setQuery ( query,Fmodel.class ).build ();
        feedsAdapter = new FeedsAdapter ( options );

        feedRecyclerView = (RecyclerView) findViewById ( R.id.feedrecycler );
        feedRecyclerView.setHasFixedSize ( true );
        feedRecyclerView.setLayoutManager ( new LinearLayoutManager ( this ) );
        feedRecyclerView.setAdapter ( feedsAdapter);
    }

    @Override
    protected void onStart() {
        super.onStart ( );
        feedsAdapter.startListening ();
        Toast.makeText ( this, "fetch on", Toast.LENGTH_SHORT ).show ( );

    }

    @Override
    protected void onStop() {
        super.onStop ( );
        feedsAdapter.stopListening ();
        Toast.makeText ( this, "fetch off", Toast.LENGTH_SHORT ).show ( );
    }
}

model class

  package gk.com.Model;

public class Fmodel {


    private String fname;
    private String faddress;
    private String fmobile;
    private String fmessage;


    public Fmodel() {
    }

    public Fmodel(String fname, String faddress, String fmobile, String fmessage) {
        this.fname = fname;
        this.faddress = faddress;
        this.fmobile = fmobile;
        this.fmessage = fmessage;
    }

    public String getFname() {
        return fname;
    }

    public void setFname(String fname) {
        this.fname = fname;
    }

    public String getFaddress() {
        return faddress;
    }

    public void setFaddress(String faddress) {
        this.faddress = faddress;
    }

    public String getFmobile() {
        return fmobile;
    }

    public void setFmobile(String fmobile) {
        this.fmobile = fmobile;
    }

    public String getFmessage() {
        return fmessage;
    }

    public void setFmessage(String fmessage) {
        this.fmessage = fmessage;
    }
}

Answer 1

You are getting a "blank" activity most likely because of the following lines of code:

Query query = collectionReference.orderBy ( "Fname", Query.Direction.ASCENDING );

Meaning that you are trying to query the FeedBacks collection and order the results according to the Fname property. That line of code makes me think that in your database you have the fname property that starts with an upper case, which is not correct since the fname property in your Fmodel class starts with a lower case. To make it work, both properties must match. To solve this, please check my answer from the following post:

how to read firestore sub-collection and pass it to FirestoreRecyclerOptions