slider

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  double reading=0.0;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: <Widget>[
          Slider(
              value: reading,
              min: 0.0,
              max: 100.0,
              inactiveColor: Colors.grey,
              activeColor: Colors.orange,
              label: 'value:$reading',
              divisions: 10,
              onChanged: (data){setState(() {
                reading = data;
              });})
        ],
      ),
    );
  }
}