Having problem to fetching file from firestore recycle view

Question

I am an android developer beginner, I am having a problem fetch files from firestore recycle view in the main activity but I can fetch files from fragments.

This is my main activity

public class FoodInfoActivity extends AppCompatActivity {
RecyclerView recyclerView1,recyclerView2;
    private FirebaseFirestore db = FirebaseFirestore.getInstance();
    private CollectionReference notebookRef;
    private NoteAdapter adapter;
    FirebaseAuth fAuth;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_food_info);
        fAuth = FirebaseAuth.getInstance();
        setUpRecyclerView();
    }

    private void setUpRecyclerView() {
        notebookRef = db.collection("FoodInside");
        Query query = notebookRef;
        FirestoreRecyclerOptions<FoodAdapter> options = new FirestoreRecyclerOptions.Builder<FoodAdapter>()
                .setQuery(query, FoodAdapter.class)
                .build();
        adapter = new NoteAdapter(options);
        RecyclerView recyclerView = findViewById(R.id.fi);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(adapter);


    }
        }

This is my Note adapter where i use model class to fetch file

public class NoteAdapter extends FirestoreRecyclerAdapter<FoodAdapter, NoteAdapter.NoteHolder> {
    public NoteAdapter(@NonNull FirestoreRecyclerOptions<FoodAdapter> options) {
        super(options);
    }
    @Override
    protected void onBindViewHolder(@NonNull NoteHolder holder, int position, @NonNull FoodAdapter foodAdapter) {
        holder.textViewTitle.setText(foodAdapter.getRestaurant());
        holder.textViewDescription.setText(foodAdapter.getItem());
        holder.textViewPriority.setText(String.valueOf(foodAdapter.getPrice()));
    }
    @NonNull
    @Override
    public NoteHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.food_recycle_layout,
                parent, false);
        return new NoteHolder(v);
    }
    class NoteHolder extends RecyclerView.ViewHolder {
        TextView textViewTitle;
        TextView textViewDescription;
        TextView textViewPriority;
        public NoteHolder(View itemView) {
            super(itemView);
            textViewTitle = itemView.findViewById(R.id.textView95a);
            textViewDescription = itemView.findViewById(R.id.textView123a);
            textViewPriority = itemView.findViewById(R.id.textView124a);
        }
    }
}

This is my adapter class ,

public class FoodAdapter {
    String Restaurant;
    String Item;
    String Price;
    String item_id;

    public FoodAdapter() {
    }

    public FoodAdapter(String restaurant, String item, String price,String item_id) {
        Restaurant = restaurant;
        Item = item;
        Price = price;
        this.item_id = item_id;
    }
public String getRestaurant() {
    return Restaurant;
}

public void setRestaurant(String restaurant) {
    Restaurant = restaurant;
}

public String getItem() {
    return Item;
}

public void setItem(String item) {
    Item = item;
}

public String getPrice() {
    return Price;
}

public void setPrice(String price) {
    Price = price;
}

public String getItem_id() {
    return item_id;
}

public void setItem_id(String item_id) {
    this.item_id = item_id;
}
}

Why it is not working in main activity but work fragment. I am just afraid. and tired...working on the project. so need solution of this problem

Answer 1

@Override
protected void onStart() {
    super.onStart();
    adapter.startListening();
}


@Override
protected void onStop() {
    super.onStop();
    adapter.stopListening();
}

Add this line to main activity.