Widget Divider

main.dart

import 'package:flutter/material.dart';

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

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

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Demo'),
      ),
      body: Column(
        children: <Widget>[
          Text('Hello World 1'),
          Divider(thickness: 2.0),
          Text('Hello World 2'),
        ]
      ),
    );
  }
}