RecyclerView 状态栏滑动渐变

  recyclerviewName.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
            }
        int aa = 0;
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);
            aa = aa + dy;
            if (aa < 700){
                歌单顶栏.setBackgroundColor(Color.argb((int) 0, 0, 0, 0));
                float percent = aa * 1f / 700;//百分比
                int alpha = (int) (percent * 255);
                歌单顶栏.setBackgroundColor(Color.argb((int) alpha, 161, 196, 253));
            }else {
                歌单顶栏.setBackgroundColor(Color.argb((int) 255, 161, 196, 253));
            }

        }
    });