I have question why my recyclerview is not updating data in real time when new was added? I getting data from firestore adding to list and passing to android view model class. Then i put in Live Data and passing to fragment. From fragment i sending to recyclerView Adapter. And later when i want to add new data it not displaying in recycler view. Maybe someone have solution to this problem?
This is my fragment where i getting data
userViewModel.getDiscountList().observe(this, new Observer<List<DiscountModel>>() {
@Override
public void onChanged(@Nullable final List<DiscountModel> discountModels) {
if (discountModels.size() != 0) {
if (adapter != null) {
discountAdapter.setData(discountModels);
dicountRecyclerView.scrollToPosition(0);
} else {
discountAdapter = new DiscountRecyclerViewAdapter(getContext(), discountModels);
dicountRecyclerView.setAdapter(discountAdapter);
}
dicountRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
int firstItemVisible = layoutManager.findFirstVisibleItemPosition();
if (firstItemVisible != 0 && firstItemVisible % discountModels.size() == 0) {
recyclerView.getLayoutManager().scrollToPosition(0);
}
}
});
}
}
});
}
Here is my RecyclerView Adapter
public void setData(List<DiscountModel> newData) {
if (mDiscount != null) {
PostDiffCallback postDiffCallback = new PostDiffCallback(mDiscount, newData);
DiffUtil.DiffResult diffResult = DiffUtil.calculateDiff(postDiffCallback);
mDiscount.clear();
mDiscount.addAll(newData);
diffResult.dispatchUpdatesTo(this);
} else {
// first initialization
mDiscount = newData;
}
}
class PostDiffCallback extends DiffUtil.Callback {
private final List<DiscountModel> oldPosts, newPosts;
public PostDiffCallback(List<DiscountModel> oldPosts, List<DiscountModel> newPosts) {
this.oldPosts = oldPosts;
this.newPosts = newPosts;
}
@Override
public int getOldListSize() {
return oldPosts.size();
}
@Override
public int getNewListSize() {
return newPosts.size();
}
@Override
public boolean areItemsTheSame(int oldItemPosition, int newItemPosition) {
return oldPosts.get(oldItemPosition).getDiscountId() == newPosts.get(newItemPosition).getDiscountId();
}
@Override
public boolean areContentsTheSame(int oldItemPosition, int newItemPosition) {
return oldPosts.get(oldItemPosition).equals(newPosts.get(newItemPosition));
}
}
This is my Android View Model Class
private MutableLiveData<List<DiscountModel>> discountList;
public LiveData<List<DiscountModel>> getDiscountList() {
if (discountList == null) {
discountList = new MutableLiveData<>();
userRepository.getUserDiscounts(new MyFirebaseCallBack<List<DiscountModel>>() {
@Override
public void onSuccessCallback(List<DiscountModel> object) {
if (object != null) {
discountList.setValue(object);
}
}
@Override
public void onFailureCallback(String message) {
}
});
}
return discountList;
}
