Android? RecyclerView? ??? Firestore ??? ??

??? ??? ??? ??? ??? ????? ???? ??? ??? ???? ? ???? ??? ?????. Firestore??? ?? ??? Limit() ???? ???? ??? ??? ??? ? ????.

???:

RecyclerView?? Firestore ???? ???? ???? ?? ??? ????.

1. ??? ?? ??:

   • limit(int): ???? ???? ?? ?? ?? ??? ?????(?: 15).
   • lastVisible(DocumentSnapshot): ???? ?????. ?? ????? ? ? ?? ??.
   • isScrolling, isLastItemReached (??): ??? ? ??? ??? ??? ???? ???.

2. ?? ?? ??:

   • ???? ??? Firestore ??? ?????(?: "productName").
   • ??? ??? ?????(?: .limit(limit)).

3. ?? ?? ???? ??:

   • query.get().addOnCompleteListener()? ???? ??? ? ?? ???? ?????.
   • ??? ?? ???(?: ProductModel)? ?? ?????. ).
   • RecyclerView ???? ??? ?????. list.

4. ??? ??? ?? ??:

   • RecyclerView.OnScrollListener? RecyclerView? ?????.
   • onScrolled()?? ???? ????? ?????. ?? ???? ?? ??? ???? ? ?? ?? ??.
   • ???? lastVisible ?? ???? ? ??? ???? ??? ?? ?????.
   • ?? ???? ?????. ??? ???? ???? ???????.

5. ??? ?? ???:

   • ??? ??? ???? ??? ?????. ???? ??? isLastItemReached? true? ???? ??? ??? ?? ?????.

?? ??:

FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
CollectionReference productsRef = rootRef.collection("products");
Query query = productsRef.orderBy("productName", Query.Direction.ASCENDING).limit(limit);

query.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
    @Override
    public void onComplete(@NonNull Task<QuerySnapshot> task) {
        if (task.isSuccessful()) {
            for (DocumentSnapshot document : task.getResult()) {
                ProductModel productModel = document.toObject(ProductModel.class);
                list.add(productModel);
            }
            productAdapter.notifyDataSetChanged();
            lastVisible = task.getResult().getDocuments().get(task.getResult().size() - 1);

            RecyclerView.OnScrollListener onScrollListener = new RecyclerView.OnScrollListener() {
                @Override
                public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                    LinearLayoutManager linearLayoutManager = ((LinearLayoutManager) recyclerView.getLayoutManager());
                    int firstVisibleItemPosition = linearLayoutManager.findFirstVisibleItemPosition();
                    int visibleItemCount = linearLayoutManager.getChildCount();
                    int totalItemCount = linearLayoutManager.getItemCount();

                    if (isScrolling &amp;&amp; (firstVisibleItemPosition + visibleItemCount == totalItemCount) &amp;&amp; !isLastItemReached) {
                        isScrolling = false;
                        Query nextQuery = productsRef.orderBy("productName", Query.Direction.ASCENDING).startAfter(lastVisible).limit(limit);
                        nextQuery.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                            @Override
                            public void onComplete(@NonNull Task<QuerySnapshot> t) {
                                if (t.isSuccessful()) {
                                    for (DocumentSnapshot d : t.getResult()) {
                                        ProductModel productModel = d.toObject(ProductModel.class);
                                        list.add(productModel);
                                    }
                                    productAdapter.notifyDataSetChanged();
                                    lastVisible = t.getResult().getDocuments().get(t.getResult().size() - 1);

                                    if (t.getResult().size() < limit) {
                                        isLastItemReached = true;
                                    }
                                }
                            }
                        });
                    }
                }
            };
            recyclerView.addOnScrollListener(onScrollListener);
        }
    }
});

? ??? ??? Android?? Firestore ???? ?? ???? ??? ??? ??? ??? ? ????. ?????.

? ??? Android?? RecyclerView? ???? Firestore ??? ??? ???? ??? ??????? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!