无法在RecyclerView中添加footerView

public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    private static final int VIEW_TYPE_ITEM = 0;
    private static final int VIEW_TYPE_FOOTER = 1;

    private List<Item> itemList;
    private View footerView;

    public MyAdapter(List<Item> itemList) {
        this.itemList = itemList;
    }

    public void addFooterView(View footerView) {
        this.footerView = footerView;
        notifyItemInserted(itemList.size());
    }

    @Override
    public int getItemViewType(int position) {
        if (position == itemList.size()) {
            return VIEW_TYPE_FOOTER;
        } else {
            return VIEW_TYPE_ITEM;
        }
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == VIEW_TYPE_ITEM) {
            // create and return item view holder
        } else if (viewType == VIEW_TYPE_FOOTER) {
            // create and return footer view holder
        }
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof ItemViewHolder) {
            // bind item data
        } else if (holder instanceof FooterViewHolder) {
            // bind footer view
        }
    }

    @Override
    public int getItemCount() {
        return itemList.size() + 1; // add 1 for footer view
    }

    private class ItemViewHolder extends RecyclerView.ViewHolder {
        // item view holder implementation
    }

    private class FooterViewHolder extends RecyclerView.ViewHolder {
        // footer view holder implementation
    }
}

RecyclerView recyclerView = findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));

MyAdapter adapter = new MyAdapter(itemList);
View footerView = LayoutInflater.from(this).inflate(R.layout.footer_view, recyclerView, false);
adapter.addFooterView(footerView);

recyclerView.setAdapter(adapter);