回收站列表视图项更改后更新片段文本视图的正确逻辑是什么

Question

我正在为我的应用程序创建购物车。我在片段中使用了 RecyclerView 和静态 View 。我的 RecyclerView 项上有 delete 按钮。

RecyclerView.Adapter.java

public class ShoppingCartRecyclerAdapter extends RecyclerView.Adapter<ShoppingCartViewHOlder> {

    //
    // Other `RecyclerView` adapter's methods
    //

    @Override
    public void onBindViewHolder(final ShoppingCartViewHOlder holder, final int position) {

        holder.name.setText(cart.getProductName());                          // name

        holder.sellingPrice.setText(pricePrefix(cart.getSellingPrice()));    // selling price

        // Quantity spinner adapter
        ArrayAdapter<String> spinnerAdapter = new ArrayAdapter<String>(context,
                android.R.layout.simple_spinner_item, PRODUCT_QUANTITY);

        holder.quantity.setAdapter(spinnerAdapter);                             // quantity

        holder.quantity.setSelection(cart.getQuantity() - 1);

        holder.quantity.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                int quantity = position + 1;

                // selling price as per selected quantity
                holder.sellingPrice.setText(pricePrefix(cart.getSellingPrice() * quantity));

            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                // Quantity not selected
                Toast.makeText(context, "Quantity not selected", Toast.LENGTH_SHORT).show();
            }
        });

        holder.delete.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {                                           // Delete

                if (isOnline(context)){

                    cartService.removeFromOnlineCart(cart.getProductId());          // remove data from server and db.

                    cartList.remove(position);                                      // remove item from list

                    notifyItemRemoved(position);                                    // notify list changed

                    notifyItemRangeChanged(position, getItemCount());               // to delete item in real time

                } else {

                    offlineMessage(context);
                }
            }
        });
    }
}

class ShoppingCartViewHOlder extends RecyclerView.ViewHolder { 

    Spinner quantity;

    TextView name, sellingPrice, delete;

    public ShoppingCartViewHOlder(View view) {
        super(view);

        name = (TextView) view.findViewById(R.id.my_cart_list_name);                 // name

        sellingPrice = (TextView) view.findViewById(R.id.my_cart_list_price);        // selling price

        quantity = (Spinner) view.findViewById(R.id.my_cart_quantity);               // quantity

        delete = (TextView) view.findViewById(R.id.my_cart_list_delete);             // delete
    }
}

我的Fragment.java

public class MyCartFragment extends Fragment implements View.OnClickListener{

    private List<GetShoppingCartBean> shoppingCartList;

    private RecyclerView recyclerView;

    private ShoppingCartRecyclerAdapter adapter;

    private TextView grandAmount;

    private double sellGrandPrice = 0;  // grand total.

    public MyCartFragment() {}

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_my_cart, container, false);

        // my other code...

        // Grand total amount
        grandAmount = (TextView) view.findViewById(R.id.my_cart_list_grand_total);

        // Recycler view
        recyclerView = (RecyclerView) view.findViewById(R.id.my_cart_recycler_view);
        recyclerView.setLayoutManager(new LinearLayoutManager(getContext(),
                LinearLayoutManager.VERTICAL, false));            

        // get shopping cart items
        webServiceCall();

        return view;
    }

    /** Fetch cart items from server */
    private void webServiceCall() {

        // My server connector code here to fetch cart items....
        // on received response, if JsonArray is not empty

        // iterating items for selling price adding it to grand amount.
        for(GetShoppingCartBean bean: shoppingCartList){
            sellGrandPrice += bean.getSellingPrice();
        }

        // setting adapter to list view
        adapter = new ShoppingCartRecyclerAdapter(getContext(), shoppingCartList,
                getActivity().getSupportFragmentManager());

        recyclerView.setAdapter(adapter);

        // showing total price of all items.
        DecimalFormat formatter = new DecimalFormat("#,##,##,##,###.00");
        String amount = "Rs. "+ (sellGrandPrice == 0 ? 0 : formatter.format(sellGrandPrice));
        grandAmount.setText(amount);
}

目前我是第一次获取所有产品的总金额，但是如果我从列表中删除任何项目或更新数量，我的总金额没有改变。屏幕看起来类似于下面的快照，只是有删除按钮而不是现在预订。

注意：我在 webServiceCall()、RecyclerView.Adapter 基本方法等中省略了一些代码，如 HttpUrlConnection 代码等 post 有意地保持 post 简短。

Answer 1

我将 Adapter 和 Fragment class 放在不同的文件中。我合并了 class，在片段 class 中创建了私有内部适配器 class 和一种重新计算销售价格乘以数量并在我的数量 textView 中更新它的方法 setOnItemSelectedListener、删除侦听器和 Web 服务调用。

private void calculateGrandTotal(List<GetShoppingCartBean> cartBeans){
    double total = 0;
    for(GetShoppingCartBean cart: cartBeans){
        total += (cart.getSellingPriceWithOffer() * cart.getQuantity());
    }
    String price = grandPriceSuffix(total);
    grandAmount.setText(price);
}

回收站列表视图项更改后更新片段文本视图的正确逻辑是什么

What is proper logic to update text view on fragment after change in item of recycler list view

logic

android

android-fragments

android-recyclerview