在recyclerview中修改这些对象后创建对象的子列表

Question

我正在构建购物车方法，我从响应中获取对象列表，将其添加到适配器（Recyclerview.Adapter）。每个对象都有它的数量，在视图中，我有一个加号按钮和一个减号按钮，当点击时我改变了对象的数量。 当我完成点击加号和减号按钮后，（在保留一定数量的物品后），按一下检查购物车按钮。当我按下该按钮时，我需要在适配器上有一个修改版本的列表的子列表，仅包含具有正数量的对象。 到目前为止这是我的代码：  我的ViewHolder上的按钮：

  @OnClick(R.id.item_items_order_now_plus)
    public void onAddItemClicked() {
        ShoppingCartList.getInstance().increaseTotalSize();
        dataItem.increaseQuantity();
        shoppingCartListChanged.smthChanged();
        plusclicked++;
        previouslyRemoved = true;
        ShoppingCartList.getInstance().getShoppingCartItems().add(getAdapterPosition(), dataItem);
        if (plusIncreaseNumber.getVisibility() == View.GONE) {
            plusIncreaseNumber.setVisibility(View.VISIBLE);
        }

        plusIncreaseNumber.setText(plusclicked + "");

    }

    @OnClick(R.id.item_items_order_now_minus)
    public void onRemoveItemClicked() {
        if (plusIncreaseNumber.getVisibility() == View.GONE) {
            return;
        }
        if (plusclicked > 0) {
            dataItem.increaseQuantity();
            ShoppingCartList.getInstance().decreaseTotalSize();
            plusclicked--;
            plusIncreaseNumber.setText(plusclicked + "");
        }
        if (plusclicked == 0) {
            if (previouslyRemoved) {
                ShoppingCartList.getInstance().getShoppingCartItems().remove(getAdapterPosition());
            }
            plusIncreaseNumber.setVisibility(View.GONE);
            return;
        }


    }

ShoppingCartListClass： （用于保存要显示它们的项目总数，并且只使用一个列表）

public class ShoppingCartList {
    private static ShoppingCartList shoppingCartList;
    private static int totalSize;
    private ShoppingCartList(){

    }
    public static ShoppingCartList getInstance(){
        if (shoppingCartList==null){
            shoppingCartList=new ShoppingCartList();
        }
        return shoppingCartList;
    }

    private static List<al.baboon.restaurant.restsapp.response.dashboardReport.specificCategoriesResponse.DataItem> shoppingCartItems=new ArrayList<>();
    public List<al.baboon.restaurant.restsapp.response.dashboardReport.specificCategoriesResponse.DataItem> getShoppingCartItems(){
        return shoppingCartItems;
    }
    public static int getTotalSize(){
        return totalSize;
    }

    public static void increaseTotalSize(){
        totalSize++;
    }
    public static void decreaseTotalSize(){
        if (totalSize>0){
            totalSize--;
        }
    }
    public static void emptyTotalSize(){
        totalSize=0;
    }

}