android - 当列表项快速滚动时，setOnScrollListener 不起作用

Question

我尝试实现教程中描述的粘性标题 ListView

http://javatechig.com/android/listview-header-parallax-with-sticky-view-in-android

问题是当我快速滚动列表时，标题没有按要求移动到屏幕顶部。

我尝试在以下方法中记录 topY 和 heroTopY 的值。

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {

            /* Check if the first item is already reached to top.*/
            if (view.getFirstVisiblePosition() == 0) {
                View firstChild = listView.getChildAt(0);
                topY = 0;
                if (firstChild != null) {
                    topY = firstChild.getTop();
                    Log.d("topY", "" + topY);
                }

                heroTopY = stickyViewSpacer.getTop();
                Log.e("heroTopY", "" + heroTopY);
                Log.d("topY,heroTopY", topY + "," + heroTopY);
                stickyView.setY(Math.max(0, heroTopY + topY));

                // Set the image to scroll half of the amount that of ListView
                heroImageView.setY(topY * 0.5f);
            }
        }

日志输出为:

09-01 17:35:23.692  19530-19530/com.javatechig.parallaxlistview D/topY﹕ 0
09-01 17:35:23.692  19530-19530/com.javatechig.parallaxlistview E/heroTopY﹕ 500
09-01 17:35:23.692  19530-19530/com.javatechig.parallaxlistview D/topY,heroTopY﹕ 0,500
09-01 17:35:23.856  19530-19530/com.javatechig.parallaxlistview D/topY﹕ -29
09-01 17:35:23.856  19530-19530/com.javatechig.parallaxlistview E/heroTopY﹕ 500
09-01 17:35:23.856  19530-19530/com.javatechig.parallaxlistview D/topY,heroTopY﹕ -29,500
09-01 17:35:23.873  19530-19530/com.javatechig.parallaxlistview D/topY﹕ -72
09-01 17:35:23.873  19530-19530/com.javatechig.parallaxlistview E/heroTopY﹕ 500
09-01 17:35:23.873  19530-19530/com.javatechig.parallaxlistview D/topY,heroTopY﹕ -72,500
09-01 17:35:23.892  19530-19530/com.javatechig.parallaxlistview D/topY﹕ -84
09-01 17:35:23.892  19530-19530/com.javatechig.parallaxlistview E/heroTopY﹕ 500
09-01 17:35:23.892  19530-19530/com.javatechig.parallaxlistview D/topY,heroTopY﹕ -84,500

从日志输出中可以看出，topY 值停留在 84，因此标题。 如何解决这个问题？任何解决方案都会有帮助!!!

Answer 1

添加这些行

if (view.getFirstVisiblePosition() == 0) {
.....
.....
}
else
{
  stickyView.setY(0);
}

这是因为当第一个项目离开 View 时你不会进入 if 语句意味着 topY 没有更新所以你必须在 else 语句中将你的 stickyView.setY() 设置为 0。