var scrollController = new ScrollController();

@override
  void initState() {
    super.initState();
    scrollController.addListener(() {
      scrollHandler();
    });
  }

//----------------------------------
scrollHandler() {
    if (scrollController.position.pixels ==
            scrollController.position.maxScrollExtent) {
        yourMethode();
    }
  }
//---------------------------------------
SingleChildScrollView(
   controller: scrollController,