android - RecyclerView notifyItemInserted 复制了之前条目的数据

Question

所以出于某种原因，每当我向我的 ArrayList 添加一个新项目并通知 recyclerview 它已被添加时，它会复制前一个条目的数据。因此， View 已创建，但使用的是最后一个条目中的数据，而不是当前数据。

奇怪的是我使用 ORM Sugar 保存项目，所以当我检索它们时会显示正确的数据。这表明正在添加数据，但 View 未正确显示。

我只能假设每当我使用 notifyItemInserted 方法时，recyclerview 都不会调用 onBindViewHolder，因为当我使用 notifyDataSetChange() 时会显示正确的数据

这是我添加新项目的方法

@Override
    public void AddCalorieToHistoryList(int calorieAmount, int currentCalorieAmount) {
        // Get the date and the calorie amount from what the user entered.
        Date date = new Date();
        // Create the calorie history item and then save it (via ORM Sugar Library)
        CalorieHistory calorieHistory = new CalorieHistory(date.toString(), calorieAmount);
        calorieHistory.save();

        // Notify the view of the new item that should be inserted.
        historyView.InsertNewListItem(calorieHistory);

        SubtractFromCurrentCalorieAmount(calorieAmount, currentCalorieAmount);
    }

historyView的方法

@Override
    public void InsertNewListItem(CalorieHistory calorieHistoryItem) {
        // Add the new item
        calorieHistories.add(calorieHistoryItem);
        // Notify the insert so we get the animation from the default animator
        historyListAdapter.notifyItemInserted(0);
    }

这是 recyclerview 适配器

public class HistoryListAdapter extends RecyclerView.Adapter<HistoryListAdapter.HistoryListViewHolder> {

    List<CalorieHistory> calorieHistoryList;


    public HistoryListAdapter(List<CalorieHistory> historyList) {
        this.calorieHistoryList = historyList;
    }

    // I think this is run once, it generates the view holder from the layout that we are using for each list item.
    // This way it won't have to grab it each time we make a new list item. It's all stored on our view holder.
    @Override
    public HistoryListViewHolder onCreateViewHolder(ViewGroup parent, int i) {
        View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.calorie_history_item, parent, false);

        return new HistoryListViewHolder(itemView);
    }

    // This executes everytime we make a new list item, it binds the data to the view.
    @Override
    public void onBindViewHolder(HistoryListViewHolder holder, int position) {
        // Get the current calorHistory object and set it's data to the views.
        CalorieHistory calorieHistory = calorieHistoryList.get(position);
        holder.tvDate.setText(calorieHistory.date);
        holder.tvAmount.setText(String.valueOf(calorieHistory.numberOfCalories));
    }

    @Override
    public int getItemCount() {
        // Return the size of our array.
        return calorieHistoryList.size();
    }

    public static class HistoryListViewHolder extends RecyclerView.ViewHolder {
        public TextView tvDate;
        public TextView tvAmount;

        public HistoryListViewHolder(View v) {
            super(v);
            tvDate = (TextView) v.findViewById(R.id.calorie_date);
            tvAmount = (TextView) v.findViewById(R.id.calorie_amount);
        }
    }

}

Answer 1

根据列表规范，List.add(E object) 应该将项目添加到列表的END。您似乎正在向 END 添加项目，同时在第一个项目上通知插入。

为了将项目添加为第一项，您应该更改

calorieHistories.add(calorieHistoryItem);

到

calorieHistories.add(0, calorieHistoryItem);

编辑

或者，如果你真的想把项目添加到 END，你应该改变

historyListAdapter.notifyItemInserted(0);

到

historyListAdapter.notifyItemInserted(calorieHistories.size()-1);