Как считать базу данных Room из assets и вывести её в RecyclerView?

Я создал готвую БД в assets и хотел загрузить её в память приложения, чтобы выводить её в RecyclerView, написал все нужны классы (вроде бы все), но при запуске приложения просто белый экран (если перезайти в приложении так же).

MainActivity.class

public class MainActivity extends AppCompatActivity {

    private UserListAdapter userListAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button addNewUserButton = findViewById(R.id.addNewUserButton);
        addNewUserButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //startActivityForResult(new Intent(MainActivity.this, AddNewUserActivity.class), 100);
            }
        });

        initRecyclerView();

        loadUserList();
    }


    private void initRecyclerView() {
        RecyclerView recyclerView = findViewById(R.id.recyclerView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL);
        recyclerView.addItemDecoration(dividerItemDecoration);
        userListAdapter = new UserListAdapter(this);
        recyclerView.setAdapter(userListAdapter);
    }

    private void loadUserList() {
        AppDatabase db = AppDatabase.getDbInstance(this.getApplicationContext());
        List<User> userList = db.userDao().getAllUsers();
        userListAdapter.setUserList(userList);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        if (requestCode == 100) {
            loadUserList();
        }
        super.onActivityResult(requestCode, resultCode, data);
    }
}

AppDatabase.class

@Database(entities = {User.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {
    
    public abstract UserDao userDao();

    private static AppDatabase INSTANCE;

    public static AppDatabase getDbInstance(Context context) {
        if (INSTANCE == null) {
            INSTANCE = Room.databaseBuilder(context.getApplicationContext(), AppDatabase.class, "userdb.db")
                    .allowMainThreadQueries()
                    .createFromAsset("userdb.db")
                    .build();
        }
        return INSTANCE;
    }
}

UserDao.class

@Dao
public interface UserDao {

    @Query("SELECT * FROM user")
    List<User> getAllUsers();

    @Insert
    void insertUser(User... users);

}

User.class

@Entity
public class User {
    @PrimaryKey(autoGenerate =  true)
    public int uid;

    public String firstName;
    public String lastName;
}

UserListAdapter.class

public class UserListAdapter extends RecyclerView.Adapter<UserListAdapter.MyViewHolder> {

    private final Context context;
    private List<User> userList;
    public UserListAdapter(Context context) {
        this.context = context;
    }

    public void setUserList(List<User> userList) {
        this.userList = userList;
        notifyDataSetChanged();
    }

    @NonNull
    @Override
    public UserListAdapter.MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.recycler_row, parent, false);
        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull UserListAdapter.MyViewHolder holder, int position) {
        holder.tvFirstName.setText(this.userList.get(position).firstName);
        holder.tvLastName.setText(this.userList.get(position).lastName);
    }

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

    public static class MyViewHolder extends RecyclerView.ViewHolder {
        TextView tvFirstName;
        TextView tvLastName;

        public MyViewHolder(View view) {
            super(view);
            tvFirstName = view.findViewById(R.id.tvFirstName);
            tvLastName = view.findViewById(R.id.tvLastName);

        }
    }
}

activity_main.xml

<?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=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"

        android:layout_width="match_parent"
        android:layout_height="wrap_content"

        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        />

    <Button
        android:id="@+id/addNewUserButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"

        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"

        android:text="Add New User"
        android:textAllCaps="false"
        />

</androidx.constraintlayout.widget.ConstraintLayout>

recycler_row.xml

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

    <TextView
        android:id="@+id/tvFirstName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp"
        android:textColor="#000000"
        android:textSize="22sp"
        android:text="FirstName"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/tvLastName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp"
        android:textColor="#000000"
        android:text="LastName"
        android:textSize="22sp" />
</LinearLayout>