Android studio does not show recycler view firebase

I'm new here and I do not know where the question is exactly.

I'm doing a project with Android Studio and Firebase integrated, the thing is that I want to show Firebase data in a recycler view and I do not know why it does not show anything, only the blank window.

I have created the object with the firebase data, the adapter, the layout that will show the fireview and such but shows nothing

Deputy code:

Adapter.

public class Adapter extends RecyclerView.Adapter<Adapter.ComercioViewHolder>{


            List<Comercio> lista_comercios;

            public Adapter(List<Comercio> lista_comercios) {
                this.lista_comercios = lista_comercios;
            }

            @NonNull
            @Override
            public ComercioViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int i) {
                View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_recycler, parent, false);
                ComercioViewHolder holder = new ComercioViewHolder(v);
                return holder;
            }

            @Override
            public void onBindViewHolder(@NonNull ComercioViewHolder holder, int position) {
                Comercio comercio = lista_comercios.get(position);
                holder.textViewnombre.setText(comercio.getNombre());
                holder.textViewdireccion.setText(comercio.getDireccion());

            }

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

            public static class ComercioViewHolder extends RecyclerView.ViewHolder{

                TextView textViewnombre, textViewdireccion;
                public ComercioViewHolder(@NonNull View itemView) {
                    super(itemView);

                    textViewnombre = itemView.findViewById(R.id.textview_nombre);
                    textViewdireccion= itemView.findViewById(R.id.textview_direccion);
                }
            }

        }

        row_recycler.
            <?xml version="1.0" encoding="utf-8"?>
        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:orientation="vertical" android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <TextView
                android:id="@+id/textview_nombre"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

            <TextView
                android:id="@+id/textview_direccion"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

        </LinearLayout>

        activity_main. 
            package com.moisescapel.lucenamarket2;

        import android.os.Bundle;
        import android.support.annotation.NonNull;
        import android.support.v7.app.AppCompatActivity;
        import android.support.v7.widget.LinearLayoutManager;
        import android.support.v7.widget.RecyclerView;

        import com.google.firebase.database.DataSnapshot;
        import com.google.firebase.database.DatabaseError;
        import com.google.firebase.database.FirebaseDatabase;
        import com.google.firebase.database.ValueEventListener;
        import com.moisescapel.lucenamarket2.Objetos.Adapter;
        import com.moisescapel.lucenamarket2.Objetos.Comercio;

        import java.util.ArrayList;
        import java.util.List;


        public class MainActivity extends AppCompatActivity {


            RecyclerView rv ;

            List<Comercio> lista_comercios;

            Adapter adapter;

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

                rv = (RecyclerView) findViewById(R.id.recycler);

                rv.setLayoutManager(new LinearLayoutManager(this));

                lista_comercios = new ArrayList<>();

                FirebaseDatabase database = FirebaseDatabase.getInstance();

                adapter = new Adapter(lista_comercios);
                rv.setAdapter(adapter);

                database.getReference().getRoot().addValueEventListener(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

                        lista_comercios.removeAll(lista_comercios);
                        for (DataSnapshot snapShot:
                                dataSnapshot.getChildren()){
                            Comercio comercio = snapShot.getValue(Comercio.class);
                            lista_comercios.add(comercio);
                        }
                        adapter.notifyDataSetChanged();



                    }

                    @Override
                    public void onCancelled(@NonNull DatabaseError databaseError) {

                    }
                });




            }
        }

I would appreciate if you could help me