在调用2-3 notifyDataSetChanged后，RecyclerView会在onBindViewHolder中更改它的位置值

Question

• 如何获得正确的位置值。
• 在RecyclerView适配器中调用notifyDataSetChanged 2-3次后，onBindViewHolder中的位置正在改变。
• 但滚动位置相同。

我通过getItemViewType设置不同的视图。

@Override
public int getItemViewType(int position) {
    if (totalCartSize > productServiceSize) {
        if (position < productServiceSize) {
            return PRODUCT_SERVICE_TYPE;
        } else if (position >= productServiceSize && position < totalCartSize) {
            return PROJECT_TYPE;
        }
    } else {
        return PRODUCT_SERVICE_TYPE;
    }
    return super.getItemViewType(position);
}

在点击行上我有callBackListener通过再次点击服务进行刷新，但在callBack中由于onBindViewholder错误的位置，我得到了错误的值。

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    if (holder instanceof ProductServiceViewHolder) {
        setProductServiceView((ProductServiceViewHolder) holder, holder.getAdapterPosition());
    } else if (holder instanceof ProjectViewHolder) {
        setProjectView((ProjectViewHolder) holder, position);
    }
}

• 问候
• 阿布舍克巴克

Answer 1

好吧，onBindViewHolder没有任何问题，它只会改变视图值。我认为您的问题是您不完全了解RecyclerView的工作原理。

1. RecyclerView通过getItemCount
获取项目总数
2. 对于每个可见的，它获取视图类型（通过getItemViewType）
3. 对于此可见项目，他们将创建一个新的ViewHolder或回收已创建的一个（基于类型）
4. 为每个项目设置onBindViewHolder的数据。因此，如果您有4个可见项目，onBindViewHolder将被调用4次。 当一个项目变为可见时，或者当您使用notifyDataSetChanged告诉适配器数据发生更改时，将调用此方法。这没有任何问题，我认为你有类型的问题。

顺便说一句，你有一些其他更具体的方法可以在数据发生变化时阻止适配器：

- final void    notifyItemChanged(int position)
Notify any registered observers that the item at position has changed.
- final void    notifyItemChanged(int position, Object payload)
Notify any registered observers that the item at position has changed with an optional payload object.
- final void    notifyItemInserted(int position)
Notify any registered observers that the item reflected at position has been newly inserted.
- final void    notifyItemMoved(int fromPosition, int toPosition)
Notify any registered observers that the item reflected at fromPosition has been moved to toPosition.
- final void    notifyItemRangeChanged(int positionStart, int itemCount)
Notify any registered observers that the itemCount items starting at position positionStart have changed.
- final void    notifyItemRangeChanged(int positionStart, int itemCount, Object payload)
Notify any registered observers that the itemCount items starting at positionpositionStart have changed.
- final void    notifyItemRangeInserted(int positionStart, int itemCount)
Notify any registered observers that the currently reflected itemCount items starting at positionStart have been newly inserted.
- final void    notifyItemRangeRemoved(int positionStart, int itemCount)
Notify any registered observers that the itemCount items previously located at positionStart have been removed from the data set.
- final void    notifyItemRemoved(int position)
Notify any registered observers that the item previously located at position has been removed from the data set. 

官方RecyclerView.Adapter文档here。