将值添加到列表<map <String，dynamic >>

Question

是否可以从List<Map<String, dynamic>>向Future<List<Map<String, dynamic>>>添加值。 我正在尝试将更多值添加到列表中作为滚动结束。

 Future<List<Map<String, dynamic>>> _future;
            List<map<String, dynamic>> resultUrl = [];


                  @override
                  void initState() {
                   _future = fetch()
                    _scrollController.addListener(() {
                      if (_scrollController.position.pixels ==
                          _scrollController.position.maxScrollExtent) {
                        getMoreData();
                      }
                });

                super.initState();
              }


         Future<List<Map<String, dynamic>>> fetch() async {
         http.Response response = await http.get(url);
         if (response.statusCode != 200) return null;
          return List<Map<String, 
           dynamic>>.from(json.decode(response.body)['map']);
          }



//In a stateful Widget

 FutureBuilder<List<Map<String, dynamic>>>(
      future: _future,
      builder: (context, snapshot) {
        if (snapshot.hasError) {
          print(snapshot.error);
        } else {
          resultList = snapshot.data;
        }
        return resultList != null?
StaggeredGridView.countBuilder(
                crossAxisCount: 4,
                itemCount: snapshot.data.length,
                itemBuilder: (BuildContext context, int index) => new 
                  Container(
                  padding: EdgeInsets.all(2.0),
                    child: Card(
                      semanticContainer: true,
                      clipBehavior: Clip.antiAliasWithSaveLayer,
                      shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.circular(10.0),
                      ),
                      elevation: 5,
                      child: Image(
                        image: NetworkImage(resultList[index]['image']),
                        fit: BoxFit.cover,
                      ),
                    ),

                ),
                staggeredTileBuilder: (int index) =>
                    new StaggeredTile.count(2, index.isEven ? 2 : 1),
                mainAxisSpacing: 1.0,
                crossAxisSpacing: 1.0,
              );

    getMoreData() {
       resultUrl.add(_future);// resultUrl.addAll(_future);
      }