Navigating using scaffold key

first.dart

class FirstPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Material(
      child: Center(child: Text("First Page")),
    );
  }
}

home.dart

class MyHomePage extends StatelessWidget {
  final GlobalKey<ScaffoldState> _scaffoldkey = new GlobalKey<ScaffoldState>();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldkey,
      appBar: AppBar(
        title: Text("Example"),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            RaisedButton(
              child: Text("Go to 1st"),
              onPressed: () => Navigator.push(
                _scaffoldkey.currentContext,
                MaterialPageRoute(
                  builder: (_) => FirstPage(),
                ),
              ),
            ),
            RaisedButton(
              child: Text("Go to 2st"),
              onPressed: () => Navigator.push(
                _scaffoldkey.currentContext,
                MaterialPageRoute(
                  builder: (_) => SecondPage(),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

second.dart

class SecondPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Material(
      child: Center(child: Text("Second Page")),
    );
  }
}