上述代码出现了如下错误：Type mismatch: inferred type is View? but View was expected

这个错误是因为getChildAt()方法返回的是View?类型，而你在使用时需要传入View类型。可以将getChildAt()改成getChildViewHolder()，这样就可以获取到ViewHolder对象，然后再通过ViewHolder获取View： ``` override fun onLayoutChildren(recycler: RecyclerView.Recycler?, state: RecyclerView.State?) { super.onLayoutChildren(recycler, state) var totalHeight = 0 for (i in 0 until childCount) { val child = getChildViewHolder(getChildAt(i)).itemView totalHeight += child.height } if (totalHeight > height) { mRvChat.postDelayed({ mRvChat.smoothScrollToPosition(itemCount - 1) }, 1000) } } ``` 这样就可以避免类型不匹配的问题了。