How can I identify that RecyclerView's last item is visible on screen?

Question

I have one RecyclerView and I added list of data into the RecyclerView. I wanted to add more data in list, when last RecyclerView item is visible on screen. After that I want to make a web service call and update the RecyclerView data. How can I achieve this?

Any suggestions?

Answer 1

One option would involve editing your LayoutManager. The idea here is to find the position of the last visible item. If that position is equal to the last item of your dataset, then you should trigger a reload.

    @Override
    public int scrollVerticallyBy(int dy, RecyclerView.Recycler recycler, RecyclerView.State state) {

        final int result = super.scrollVerticallyBy(dy, recycler, state);

        if (findLastVisibleItemPosition() == mData.length - 1) {
           loadMoreData();
        } 

        return result;

    }

    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
        super.onLayoutChildren(recycler, state);

        if (findLastVisibleItemPosition() == mData.length - 1) {
           loadMoreData();
        } 
    }

Alternatively, you could do this via your adapter's onBindViewHolder method, although this is admittedly a bit of a "hack":

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (position == mData.length - 1) {
            // load more data here.
        }

        /// binding logic
    }

3rd option would be to add an OnScrollListener to the RecyclerView. @velval's answer on this page explains this well.

Regardless which option you go for, you should also include code to prevent the data load logic from triggering too many times (e.g., before the previous request to fetch more data completes and returns new data).

Answer 2

If someone stumble across this post this is a quick and simple tutorial on how to do it:

All you need to do is:

recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
    @Override
    public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        super.onScrollStateChanged(recyclerView, newState);
    }

    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);
        int visibleItemCount        = lm.getChildCount();
        int totalItemCount          = lm.getItemCount();
        int firstVisibleItemPosition= lm.findFirstVisibleItemPosition();

        // Load more if we have reach the end to the recyclerView
        if ( (visibleItemCount + firstVisibleItemPosition) >= totalItemCount && firstVisibleItemPosition >= 0) {
            loadMoreItems();
        }
    }
});

Then your loadMoreItems() should look something like this:

private void loadMoreItems() {
    // init offset=0 the frist time and increase the offset + the PAGE_SIZE when loading more items
    queryOffset = queryOffset + PAGE_SIZE;
    // HERE YOU LOAD the next batch of items
    List<Items> newItems = loadItems(queryOffset, PAGE_SIZE);

    if (newItems.size() > 0) {
        items.addAll(newItems);
        adapter.notifyDataSetChanged();
    }
}

Answer 3

Seen many of the above answers but my answer is different one and it will work in your cases also. My approach is based on scroll state of recylerview. Maintain below variable "check" and this should update only once when api responds. Put below code in your api response. If you want to handle last item only on every call of api.

final boolean[] check = {true};
    recyclerView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
        @Override
        public void onScrollChanged() {
            if (!recyclerView.canScrollVertically(1)) {
                // last item of recylerview reached.
                if (check[0]) {
                    //your code for last reached item
                    scroll_handler.setVisibility(View.GONE);
                }
            } else {
                scroll_handler.setVisibility(View.VISIBLE);
                check[0] = false;
            }
        }
    });

If you want to handle your last item every time then do it as below

recyclerView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
    @Override
    public void onScrollChanged() {
        if (!recyclerView.canScrollVertically(1)) 
            // Bottom of recyler view.
            arrow_img.setRotation(180);
        }
    }
});

Answer 4

See also Android - Detect when the last item in a RecyclerView is visible.

private fun isLastItemVisible(): Boolean {
    val layoutManager = recycler_view.layoutManager
    val position = layoutManager.findLastCompletelyVisibleItemPosition()
    return position >= adapter.itemCount - 1
}