Enable Show Scrollbar Indicator Scrollview Using Flutter App

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
        home: Scaffold(
          backgroundColor: Colors.black,
          appBar: AppBar(
            centerTitle: true,
            backgroundColor: Colors.white,
            title: Text('Enable Show Scrollbar Indicator ScrollView',
              style: TextStyle(
              color: Colors.black
            )),
          ),
            body: SafeArea(
                child: Scrollbar(
                  child: SingleChildScrollView(
                    child: Column(
                      children: <Widget>[
                        Positioned(
                          bottom: 48.0,
                          left: 10.0,
                          right: 10.0,
                          child: Card(
                            color: Colors.pink,
                            elevation: 8.0,
                            shape: RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(8.0),
                            ),
                            child: Column(
                              children: <Widget>[
                                Padding(
                                  padding: const EdgeInsets.all(16.0),
                                  child: Text(
                                    "India",
                                    style: TextStyle(
                                      fontSize: 20.0,
                                      fontWeight: FontWeight.bold,
                                      color: Colors.white
                                    ),
                                  ),
                                ),
                                Padding(
                                  padding: const EdgeInsets.all(16.0),
                                  child: Text(
                                      "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.",style: TextStyle(
                                    color: Colors.white
                                  ),),
                                ),
                              ],
                            ),
                          ),
                        ),
                        Positioned(
                          bottom: 48.0,
                          left: 10.0,
                          right: 10.0,
                          child: Card(
                            color: Colors.deepPurple,
                            elevation: 8.0,
                            shape: RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(8.0),
                            ),
                            child: Column(
                              children: <Widget>[
                                Padding(
                                  padding: const EdgeInsets.all(16.0),
                                  child: Text(
                                    "India",
                                    style: TextStyle(
                                      fontSize: 20.0,
                                      fontWeight: FontWeight.bold,
                                        color: Colors.white
                                    ),
                                  ),
                                ),
                                Padding(
                                  padding: const EdgeInsets.all(16.0),
                                  child: Text(
                                      "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.",style: TextStyle(
                                    color: Colors.white
                                  ),),
                                ),
                              ],
                            ),
                          ),
                        ),
                        Positioned(
                          bottom: 48.0,
                          left: 10.0,
                          right: 10.0,
                          child: Card(
                            color: Colors.green,
                            elevation: 8.0,
                            shape: RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(8.0),
                            ),
                            child: Column(
                              children: <Widget>[
                                Padding(
                                  padding: const EdgeInsets.all(16.0),
                                  child: Text(
                                    "India",
                                    style: TextStyle(
                                      fontSize: 20.0,
                                      fontWeight: FontWeight.bold,
                                      color: Colors.white
                                    ),
                                  ),
                                ),
                                Padding(
                                  padding: const EdgeInsets.all(16.0),
                                  child: Text(
                                      "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.",style: TextStyle(
                                    color: Colors.white
                                  ),),
                                ),
                              ],
                            ),
                          ),
                        ),
                        SizedBox(height: 10,),
                        Positioned(
                          bottom: 48.0,
                          left: 10.0,
                          right: 10.0,
                          child: Card(
                            color: Colors.red,
                            elevation: 8.0,
                            shape: RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(8.0),
                            ),
                            child: Column(
                              children: <Widget>[
                                Padding(
                                  padding: const EdgeInsets.all(16.0),
                                  child: Text(
                                    "India",
                                    style: TextStyle(
                                      fontSize: 20.0,
                                      fontWeight: FontWeight.bold,
                                      color: Colors.white
                                    ),
                                  ),
                                ),
                                Padding(
                                  padding: const EdgeInsets.all(16.0),
                                  child: Text(
                                      "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.",style: TextStyle(
                                    color: Colors.white
                                  ),),
                                ),
                              ],
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                )
            )
        )
    );
  }
}