Java 如何隐藏顶部回收器视图中的浮动操作按钮，并在向下搜索时显示？

我试图只在“回收器”视图向下滚动时显示浮动操作按钮，而在“位置”位于最顶端时隐藏。很抱歉，我的英语很差{

recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
    @Override
    public void onScrolled(RecyclerView recyclerView, int dx,int dy){
        super.onScrolled(recyclerView, dx, dy);

        if (dy >0) {
            // Scroll Down
            if (fab.isShown()) {
                fab.hide();
            }
        }
        else if (dy <0) {
            // Scroll Up
            if (!fab.isShown()) {
                fab.show();
            }
        }
     }
})

@凌驾 已填空的公共空间（RecyclerView RecyclerView、int dx、int dy）{ super.onScrolled（recyclerView、dx、dy）； 如果（dy>0）{ //向下滚动 if（fab.isShown（））{ 制作隐藏（）； } }

---

else if（dy这里您可以做什么来识别滚动状态

 recyclerview.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
            super.onScrollStateChanged(recyclerView, newState);

            if (!recyclerView.canScrollVertically(1) && newState==RecyclerView.SCROLL_STATE_IDLE) {

               //do what you want if recyclerview scrolled to bottom
            }else{

                //do what you want if recyclerview not scrolled to bottom
            }
        }
    });

---

添加recylerview的滚动侦听器&滚动时隐藏fab

 fun hideFabWhenScroll(fab: FloatingActionButton, recyclerView: RecyclerView){
    recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
        override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
            if (dy > 0 || dy < 0 && fab.isShown) {
                fab.hide()
            }
        }

        override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
            if (newState == RecyclerView.SCROLL_STATE_IDLE) {
                fab.show()
            }

            super.onScrollStateChanged(recyclerView, newState)
        }
    })
}

fun hideFabWhenScroll（fab:floatingAction按钮，recyclerView:recyclerView）{
recyclerView.addOnScrollListener（对象：recyclerView.OnScrollListener（）{
覆盖已克隆的乐趣（recyclerView:recyclerView，dx:Int，dy:Int）{
if（dy>0 | | dy<0&&fab.isShown）{
制作隐藏
}
}
覆盖CrollStateChanged（recyclerView:recyclerView，newState:Int）{
if（newState==RecyclerView.SCROLL\u STATE\u IDLE）{
制作秀
}
super.onScrollStateChanged（recyclerView、newState）
}
})
}