在滚动的视图观测滚动事件的Android库：Android-ObservableScrollView

在滚动的视图观测滚动事件的Android库
它易于与在Android 5.0 Lollipop中引入的工具条Toolbar相交互，并能够帮助实现Material Design apps的外观。

支持的控件

Widget	Since	Note
ListView	v1.0.0
ScrollView	v1.0.0
WebView	v1.0.0
RecyclerView	v1.1.0	It's supported but RecyclerView provides scroll states and position with OnScrollListener. You should use it if you don't have any reason.
GridView	-

    @Override      public void onUpOrCancelMotionEvent(ScrollState scrollState) {          ActionBar ab = getSupportActionBar();          if (scrollState == ScrollState.UP) {              if (ab.isShowing()) {                  ab.hide();              }          } else if (scrollState == ScrollState.DOWN) {              if (!ab.isShowing()) {                  ab.show();              }          }      }