RecyclerView scrollToPosition不会触发scrollListener [英] RecyclerView scrollToPosition not trigger scrollListener

问题描述

我正在使用RecyclerView和ScrollListener:

I'm using RecyclerView, with ScrollListener:

mRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener()
{
        @Override
        public void onScrollStateChanged(RecyclerView recyclerView, int newState)
        {
            super.onScrollStateChanged(recyclerView, newState);
        }

        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy)
        {
            super.onScrolled(recyclerView, dx, dy);
            // Do my logic
        }
 });

当我用手指滚动时，滚动侦听器触发得很好.

When I scroll with the finger, the scroll listener triggered fine.

但是当我按比例滚动时，像这样:

But when I scroll progrematically, like that:

mRecyclerView.scrollToPosition(LAST_POSITION);

滚动侦听器未触发.

推荐答案

这是一个已知问题.这是由于RecyclerView不知道LayoutManager如何处理滚动或根本不处理滚动引起的.

This is a known issue. It is caused by the fact that RecyclerView does not know how LayoutManager will handle the scroll or if it will handle it at all.

在下一个版本中，如果在布局之后第一个和/或最后一个子位置发生变化(通常是调用滚动到位置的结果)，您将收到对onScrolled的调用.

In the next release, you'll receive a call to onScrolled if first and or last child position changes after a layout (which is generally the result of calling scroll to position).

不幸的是，由于RecyclerView并不真正知道滚动了多少布局管理器来处理scrollTo请求，因此dx和dy将为0.另外，您也可以使用ViewTreeObserver的滚动回调.

Unfortunately, dx and dy will be 0 because RecyclerView does not really know how much layout manager did scroll to handle scrollTo request. Alternatively, you can also use the the ViewTreeObserver's scroll callback.

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