How to add scroll indicator in ListView

Thanks to Günter Zöchbauer.

You can wrap your ListView in Scrollbar

Scrollbar(
    child: ListView.builder(
      itemCount: 50,
      itemBuilder: (context, index) => ListTile(title: Text("Item= ${index + 1}"),),),
)

I think better to use CupertinoScrollbar instead of Scrollbar. CupertinoScrollbar is can touch and scroll to the bottom..

Ex:

 CupertinoScrollbar(
            child: ListView.builder(...),

Or

Scrollbar(
    child: ListView.builder(...),

You can implement this designer scrollbar library :

1. draggable_scrollbar

2. alphabet scrolling

OR

You can wrap ListView in Scrollbar widget

Scrollbar(
    child: ListView.builder(...),
)

Create a ScrollController variable (ScrollController _scrollController); Instatiate _scrollController inside initState() or wherever you want, _scrollController = ScrollController();
Add _scrollController variable inside Scrollbar and ListView properties,

controller:_scrollController

Here's the code:

ScrollController _scrollController;
  @override
  void initState() {
    super.initState();
    _scrollController = ScrollController();
  }
Scrollbar(
        isAlwaysShown: true,
         controller: _scrollController,
         child: ListView(
         controller: _scrollController,
   )

if you don't want it always shown set to false

isAlwaysShown: false,

Scrollbar(
        thickness: 10,
        isAlwaysShown: true,
        child: ListView.builder(
          itemCount: _controller().transactonsList.length,
          itemBuilder: (context, index) {
            return Card(
              elevation: 5,
              child: Container(
                padding: const EdgeInsets.only(bottom: 16),
                height: 80,
                child: Row(
                  children: [
                    SizedBox(width: 10),
                    amountOfTransaction(index),
                    SizedBox(width: 16),
                    dateAndTitleOfTransaction(index),
                  ],
                ),
              ),
            );
          },
        ),
      )

final ScrollController _scroll = ScrollController();

@override
Widget build(BuildContext context) {
  (...)
  child: ListView.builder(
    controller: _scroll,
  )
}