Trying to show Recycler View in fragment of Navigation Drawer

Question

I've created a Navigation Drawer in Android Studio, using the default Navigation Drawer Activity (Android Studio Bublebee 2021.1.1.1).

And I put a Recycler view in the fragment layout. After that I tried to get data from Firebase database, and put it in Recycler view, using Firebase UI. And since the default code is different, than in many tutorials and etc. I tried to find out how to do it myself. I did it in Fragment java file, from ui package folder.

Everything is working, no errors, no crashes, but the page is empty.

My Navigation Drawer Activity java file:

package com.example.project;

import android.os.Bundle;
import android.view.View;
import android.view.Menu;
import android.widget.TextView;

import com.example.project.classes.User;
import com.example.project.classes.product;
import com.firebase.ui.database.FirebaseRecyclerOptions;
import com.google.android.material.snackbar.Snackbar;
import com.google.android.material.navigation.NavigationView;

import androidx.annotation.NonNull;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.example.project.databinding.ActivityStoreBinding;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

public class Store extends AppCompatActivity {

    private AppBarConfiguration mAppBarConfiguration;
    private ActivityStoreBinding binding;

    private FirebaseUser user;
    private DatabaseReference dbReference;
    private String uID;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        binding = ActivityStoreBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());

        setSupportActionBar(binding.appBarStore.toolbar);
        /*binding.appBarStore.fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });*/

        DrawerLayout drawer = binding.drawerLayout;
        NavigationView navigationView = binding.navView;

        View headerView = navigationView.getHeaderView(0);
        final TextView StoreNavUsername = headerView.findViewById(R.id.store_nav_header_username);

        user = FirebaseAuth.getInstance().getCurrentUser();
        dbReference = FirebaseDatabase.getInstance().getReference("Users");
        uID = user.getUid();

        dbReference.child(uID).addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
                User userData = snapshot.getValue(User.class);

                if (userData != null){
                    String usernameData = userData.username;


                    StoreNavUsername.setText(usernameData);
                }
            }

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

            }
        });


        // Passing each menu ID as a set of Ids because each
        // menu should be considered as top level destinations.
        mAppBarConfiguration = new AppBarConfiguration.Builder(
                R.id.nav_home, R.id.nav_cart, R.id.nav_orders, R.id.nav_categories)
                .setOpenableLayout(drawer)
                .build();
        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_content_store);
        NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
        NavigationUI.setupWithNavController(navigationView, navController);

        // product


    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.store, menu);
        return true;
    }

    @Override
    public boolean onSupportNavigateUp() {
        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_content_store);
        return NavigationUI.navigateUp(navController, mAppBarConfiguration)
                || super.onSupportNavigateUp();
    }
}

Main XML file of the activity:

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <include
        android:id="@+id/app_bar_store"
        layout="@layout/app_bar_store"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <com.google.android.material.navigation.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_store"
        app:menu="@menu/activity_main_drawer" />
</androidx.drawerlayout.widget.DrawerLayout>

The fragment layout of the page with the Recycler View:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.home.HomeFragment">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/store_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

The class of the item, needed to put into the Recycler View:

package com.example.project.classes;

public class product {
    private String name, price, producer, imageurl, category, productid, sellerid;

    public product() {
    }

    public product(String name, String price, String producer, String imageurl, String category, String productid, String sellerid) {
        this.name = name;
        this.price = price;
        this.producer = producer;
        this.imageurl = imageurl;
        this.category = category;
        this.productid = productid;
        this.sellerid = sellerid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    public String getProducer() {
        return producer;
    }

    public void setProducer(String producer) {
        this.producer = producer;
    }

    public String getImageurl() {
        return imageurl;
    }

    public void setImageurl(String imageurl) {
        this.imageurl = imageurl;
    }

    public String getCategory() {
        return category;
    }

    public void setCategory(String category) {
        this.category = category;
    }

    public String getProductid() {
        return productid;
    }

    public void setProductid(String productid) {
        this.productid = productid;
    }

    public String getSellerid() {
        return sellerid;
    }

    public void setSellerid(String sellerid) {
        this.sellerid = sellerid;
    }
}

The layout of the single item, to put into Recycler View:

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:scrollbars="vertical">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15dp"
        android:layout_marginBottom="5dp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp">

        <ImageView
            android:id="@+id/product_image"
            android:layout_width="wrap_content"
            android:layout_height="200dp"/>

        <TextView
            android:id="@+id/product_name"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/product_image"
            android:layout_marginTop="5dp"
            android:textSize="20dp"
            android:textAlignment="center"
            android:textColor="@color/black"
            android:textStyle="bold"
            android:text="@string/product_name"
            />

        <TextView
            android:id="@+id/product_price"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/product_name"
            android:layout_marginTop="5dp"
            android:textSize="18dp"
            android:textAlignment="center"
            android:textColor="@color/black"
            android:textStyle="bold"
            android:text="@string/product_price"
            />

    </RelativeLayout>

</androidx.cardview.widget.CardView>

The Adapter:

package com.example.project;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import com.example.project.classes.product;
import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;

public class productAdapter extends FirebaseRecyclerAdapter<
        product, productAdapter.productViewholder> {

    public productAdapter(
            @NonNull FirebaseRecyclerOptions<product> options)
    {
        super(options);
    }

    @Override
    protected void onBindViewHolder(@NonNull productAdapter.productViewholder holder, int position, @NonNull product model) {
        holder.name.setText(model.getName());
        holder.price.setText(model.getPrice());
    }

    @NonNull
    @Override
    public productViewholder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
    {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_product_layout, parent, false);
        return new productAdapter.productViewholder(view);
    }

    class productViewholder extends RecyclerView.ViewHolder {
        TextView name, price;

        public productViewholder(@NonNull View itemView) {
            super(itemView);

            name = itemView.findViewById(R.id.product_name);
            price = itemView.findViewById(R.id.product_price);
        }
    }
}

The Java file of the page fragment:

package com.example.project.ui.home;

import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.ViewModelProvider;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.example.project.classes.product;
import com.example.project.databinding.FragmentHomeBinding;
import com.example.project.productAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

public class HomeFragment extends Fragment {

    private FragmentHomeBinding binding;

    productAdapter adapter;

    DatabaseReference productDbReference;

    public View onCreateView(@NonNull LayoutInflater inflater,
                             ViewGroup container, Bundle savedInstanceState) {
        HomeViewModel homeViewModel =
                new ViewModelProvider(this).get(HomeViewModel.class);

        binding = FragmentHomeBinding.inflate(inflater, container, false);
        View root = binding.getRoot();

        /*final TextView textView = binding.textHome;
        homeViewModel.getText().observe(getViewLifecycleOwner(), textView::setText);*/

        return root;
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        productDbReference = FirebaseDatabase.getInstance("https://health-mentor-12edb-default-rtdb.europe-west1.firebasedatabase.app/").getReference("Products");

        final RecyclerView StoreRecyclerView = binding.storeRecyclerView;
        StoreRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

        FirebaseRecyclerOptions<product> options = new FirebaseRecyclerOptions.Builder<product>()
                .setQuery(productDbReference, product.class)
                .build();

        adapter = new productAdapter(options);

        StoreRecyclerView.setAdapter(adapter);
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        binding = null;
    }
}

I'm trying to put just the name and price, without the image, for now. But the page is just empty. I feel like, I got the data from database, but just didn't write, how it should put the data into the Recycler View.