Android Pagination with MVP

Fragment.java

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

        if (!mSwipeRefreshLayout.isRefreshing() && !mEndOfList) {
            if ((visibleItemCount + firstVisibleItemPosition) >= totalItemCount - Constants.PAGINATION_MARGIN
                    && firstVisibleItemPosition >= 0
                    && totalItemCount >= Constants.PAGE_SIZE) {
                mPresenter.onLoadNextPage();
            }
        }
    }
});

What is Constants.PAGE_SIZE here?

It depends on the number of items that you want to display. 30 - 40...