RecyclerView滚动了UP/DOWN监听器

Question

我们如何知道用户是向下滚动还是向上滚动RecyclerView？

我尝试过RecyclerView#OnScrollListener,它给出了垂直滚动量和滚动状态.滚动状态空闲时,如何在开始拖动和滚动位置时获取最后一个滚动位置.

谢谢.

Answer 1

接受的答案很好,但@MaciejPigulski在下面的评论中提供了更清晰,更整洁的解决方案.我只是把它作为答案在这里.这是我的工作代码.

mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {

    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);
        if (dy > 0) {
            // Scrolling up
        } else {
            // Scrolling down
        }
    }

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

        if (newState == AbsListView.OnScrollListener.SCROLL_STATE_FLING) {
            // Do something
        } else if (newState == AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL) {
            // Do something
        } else {
            // Do something
        }
    }
});

Answer 2

试试这种方式:

private static int firstVisibleInListview;

firstVisibleInListview = yourLayoutManager.findFirstVisibleItemPosition();

在您的滚动侦听器中:

public void onScrolled(RecyclerView recyclerView, int dx, int dy) 
{
    super.onScrolled(recyclerView, dx, dy);

    int currentFirstVisible = yourLayoutManager.findFirstVisibleItemPosition();

    if(currentFirstVisible > firstVisibleInListview)
       Log.i("RecyclerView scrolled: ", "scroll up!");
    else
       Log.i("RecyclerView scrolled: ", "scroll down!");  

    firstVisibleInListview = currentFirstVisible;

}

Answer 3

如果向下滚动recyclerview,我想隐藏布局,然后如果向上滚动回收器视图则使其可见.我做了一些思考,想出了这个逻辑.变量y是全局静态int.不要忘记宣布y为static int y;

我希望它有助于某人:)

 mRecyclerView.addOnScrollListener(new EndlessRecyclerOnScrollListener(lLayout) {
           @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            // super.onScrolled(recyclerView, dx, dy);
                y=dy;
            }

            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                if(mRecyclerView.SCROLL_STATE_DRAGGING==newState){
                    //fragProductLl.setVisibility(View.GONE);
                }
                if(mRecyclerView.SCROLL_STATE_IDLE==newState){
                   // fragProductLl.setVisibility(View.VISIBLE);
                    if(y<=0){
                        fragProductLl.setVisibility(View.VISIBLE);
                    }
                    else{
                        y=0;
                        fragProductLl.setVisibility(View.GONE);
                    }
                }
            }
        });

Answer 4

另一个可以在适配器的帮助下检测滚动方向的简单解决方案：

class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyViewHolder> {
    int lastItemPosition = -1;

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        if (position > lastItemPosition) {
            // Scrolled Down
        }
        else {
            // Scrolled Up
        }
        lastItemPosition = position;
     }
}

^ 在滚动时进行项目动画时很有帮助。

PS：这会不连续地告诉你方向，直到进一步调用 onBindViewHolder 。