如何在RecyclerView滚动时向上/向下滚动底栏

我是怎么做到的:

mRecylerView.addOnScrollListener(new HideShowScrollListener() {
            @Override
            public void onHide() {
                //fab.animate().setInterpolator(new AccelerateDecelerateInterpolator()).scaleX(0).scaleY(0);
               // do your hiding animation here

            }

            @Override
            public void onShow() {
               // fab.animate().setInterpolator(new AccelerateDecelerateInterpolator()).scaleX(1).scaleY(1);
              // do your showing animation here
            }
        });

您将需要HideShowScrollListener.class

/**
* This class is a ScrollListener for RecyclerView that allows to show/hide
* views when list is scrolled.
* */
public abstract class HideShowScrollListener extends RecyclerView.OnScrollListener {
    private static final int HIDE_THRESHOLD = 20;
    private int scrolledDistance = 0;
    private boolean controlsVisible = true;

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

        if (scrolledDistance > HIDE_THRESHOLD && controlsVisible) {
            onHide();
            controlsVisible = false;
            scrolledDistance = 0;
        } else if (scrolledDistance < -HIDE_THRESHOLD && !controlsVisible) {
            onShow();
            controlsVisible = true;
            scrolledDistance = 0;
        }

        if((controlsVisible && dy>0) || (!controlsVisible && dy<0)) {
            scrolledDistance += dy;
        }
    }

    public abstract void onHide();
    public abstract void onShow();

}

因为你正在使用CoordinatorLayout你可以创建一个Behaviour可以实现你所要求的自定义的自定义,如下例所示: create一个类extends CoordinatorLayout.Behavior 如下例所示:

public class QuickReturnFloaterBehavior extends CoordinatorLayout.Behavior {

    private int distance;

    public QuickReturnFloaterBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, View child, View directTargetChild, View target, int nestedScrollAxes) {
        return (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0;
    }

    @Override public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, View child, View target, int dx, int dy, int[] consumed) {
        if (dy > 0 && distance < 0 || dy < 0 && distance > 0) {
            child.animate().cancel();
            distance = 0;
        }
        distance += dy;
        final int height = child.getHeight() > 0 ? (child.getHeight()) : 600/*update this accordingly*/;
        if (distance > height && child.isShown()) {
            hide(child);
        } else if (distance < 0 && !child.isShown()) {
            show(child);
        }
    }

    private void hide(View view) {
        view.setVisibility(View.GONE);// use animate.translateY(height); instead
    }

    private void show(View view) {
        view.setVisibility(View.VISIBLE);// use animate.translateY(-height); instead
    }

}

现在要应用此behaviour添加到您的布局

app:layout_behavior="com.example.QuickReturnFloaterBehavior"