检查 RecyclerView 是否滚动到顶部（findFirstCompletelyVisibleItemPosition 将不起作用）

Question

如何在不使用 findFirstCompletelyVisibleItemPosition ?

说明：我不能使用这个方法，因为 RecyclerView 上的项目很大，有时永远不会 "completely visible"，所以该方法将 return -1 (RecyclerView.NO_POSITION)

我需要知道这一点才能仅在回收器视图到达顶部时触发操作。

 val manager = timelineRecyclerView?.layoutManager as StaggeredGridLayoutManager
 val visibles = manager.findFirstCompletelyVisibleItemPositions(null)

已解决：包括一些代码以提供帮助

    timelineRecyclerView.addOnScrollListener(object:RecyclerView.OnScrollListener() {
        override fun onScrollStateChanged(recyclerView:RecyclerView,
                                 newState:Int) {
            super.onScrollStateChanged(recyclerView, newState)

        }
        override fun onScrolled(recyclerView:RecyclerView, dx:Int, dy:Int) {
            super.onScrolled(recyclerView, dx, dy)

            currentTimelinePosition += dy

            Log.wtf("position", currentTimelinePosition.toString())
            //if the timeline position is on its start, allow swipe and refresh
            swipeLayout.isEnabled = currentTimelinePosition == 0
        }
    })

Answer 1

您可以创建一个 RecyclerView.OnScrollListener，并跟踪它滚动了多少。

比如你只需要保留一个变量，根据垂直滚动量用onScroll更新即可。

class MyScrollListener() : RecyclerView.OnScrollListener() {

    var currentScrollPosition = 0

    override fun onScrolled(view: RecyclerView, dx: Int, dy: Int) {
        currentScrollPosition += dy

        if( currentScrollPosition == 0 ) {
            // We're at the top
        }
    }
}

检查 RecyclerView 是否滚动到顶部（findFirstCompletelyVisibleItemPosition 将不起作用）

Check if RecyclerView is scrolled on top (findFirstCompletelyVisibleItemPosition will not work)

android

kotlin

pull-to-refresh

android-recyclerview