@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text("Paging ListView"),
    ),
    body: RefreshIndicator(
      onRefresh: widget.dataSource.refresh,
      child: PagingListView<String>.builder(
        itemBuilder: (context, index, item) {
          return Card(
              child: Padding(
            padding: const EdgeInsets.all(8.0),
            child: Text("paging->$item"),
          ));
        },
        dataSource: widget.dataSource,
        loadingIndicator: Center(
          child: Padding(
            padding: const EdgeInsets.all(8.0),
            child: CircularProgressIndicator(),
          ),
        ),
        noMoreDataAvailableItem: Center(
          child: Padding(
            padding: const EdgeInsets.all(8.0),
            child: Text("no more data avaliable~"),
          ),
        ),
      ),
    ),
  );
}