Question

我有一个RecyclerView，如下图所示。

我从服务器获取食品数据，并如上所述将其绑定到RecyclerView。

在foodItemList数组的foodItemTypeList数组列表中分配食品。在foodItemTypeList数组列表中，存储类型的值及其相应的价格。

我想要的是，当用户选择一种食物类型（例如中等）时，相应的单价会更新。

这是FoodItemAdapter类：

public class FoodItemAdapter extends RecyclerView.Adapter<FoodItemAdapter.CustomViewHolder> {
    private List<FoodItem> foodItemList;
    Context context;
    String token;

    public class CustomViewHolder extends RecyclerView.ViewHolder {
        public TextView food_name, food_unit_price;
        Spinner food_item_type;
        public ImageView food_item_image;
        public Button viewDetail;

        public CustomViewHolder(View view) {
            super(view);
            food_name = (TextView) itemView.findViewById(R.id.food_name);
            food_item_type = (Spinner) itemView.findViewById(R.id.food_item_type);
            viewDetail = (Button) itemView.findViewById(R.id.viewDetail);
            food_unit_price = (TextView) itemView.findViewById(R.id.food_unit_price);
            food_item_image = (ImageView) itemView.findViewById(R.id.food_item_image);
        }
    }

    public FoodItemAdapter(Context context, List<FoodItem> foodItemList,String token) {
        this.foodItemList = foodItemList;
        this.context = context;
        this.token = token;
    }

    @Override
    public CustomViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.food_items_item, parent, false);
        return new CustomViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(final CustomViewHolder holder, int position) {
        FoodItem foodItem = foodItemList.get(position);
        holder.food_name.setText(foodItem.getFood_name());
        holder.viewDetail.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {

            }
        });

        holder.food_unit_price.setText(foodItem.getFood_unit_price()+" AF");

        if(foodItem.getFood_item_image()!=null && !foodItem.getFood_item_image().isEmpty()){
            Picasso.get()
                    .load(foodItem.getFood_item_image())
                    // To fit image into imageView
                    .resize(50, 50)
                    .centerCrop()
                    .into(holder.food_item_image);
        } else {
            Log.d("Food Item Image:", "Food Item image is either empty or null");
        }

        List<FoodItemType> foodItemTypeList = new ArrayList<>();
        foodItemTypeList = foodItem.getFoodItemTypeList();
        ArrayAdapter userAdapter = new ArrayAdapter(context, R.layout.spinner, foodItemTypeList);
        holder.food_item_type.setAdapter(userAdapter);
        holder.food_item_type.setOnItemSelectedListener(new
            AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> parent, View view, int
                        position, long id) {

                    FoodItemType foodItemType = (FoodItemType) (holder.food_item_type).getSelectedItem();
                    Toast.makeText(context, "Clicked: " +
                            foodItemType.getFood_unit_price(), Toast.LENGTH_LONG).show();
                    FoodItem foodItemNew = new FoodItem(foodItemList.get(holder.getAdapterPosition()).getFood_item_id(),foodItemList.get(holder.getAdapterPosition()).getFood_category_id(),foodItemList.get(holder.getAdapterPosition()).getFood_name(),foodItemList.get(holder.getAdapterPosition()).getFood_item_image(),foodItemList.get(holder.getAdapterPosition()).getFood_item_desc(), foodItemType.getFood_item_type_id(),foodItemType.getFood_item_type_name(),foodItemType.getFood_unit_price(), foodItemList.get(holder.getAdapterPosition()).getFoodItemTypeList());
                    foodItemList.set(holder.getAdapterPosition(),foodItemNew);
                    notifyItemChanged(holder.getAdapterPosition());
                }

                @Override
                public void onNothingSelected(AdapterView<?> parent) {
                    // todo for nothing selected
                }
            });
    }

    @Override
    public int getItemCount() {
        return foodItemList.size();
    }

}

我的FoodItemsFragment类的一部分如下：

recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_food_item);
foodItemAdapter = new FoodItemAdapter(getActivity(),foodItemList, token);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity());

recyclerView.setLayoutManager(mLayoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(foodItemAdapter);
foodItemAdapter.notifyDataSetChanged();

我的问题是：滚动RecyclerView时，视图会多次加载（有点滞后），而更改食物类型（例如：更改为中）时，什么也没发生。

感谢您提供任何帮助。

Answer 1

我建议您在FoodItem类中的另一个字段为selectedFoodType。这将保存所选类型的索引。默认情况下，将值初始化为0，并且从下拉列表中选择一项时，只需相应地更新相应的FoodItem的{{1}}。

另一件事是，您不必每次更改selectedFoodType的类型时都创建一个新的FoodItem。您只需要拥有FoodItem，然后调用selectedFoodType。

因此，代码应如下所示。在notifyDataSetChanged()函数内部，执行以下操作。

onItemSelected

请注意，我尚未测试此代码。请根据您的需要进行修改。希望有帮助！

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