Controlling State from outside of a StatefulWidget

Question

I\'m trying to understand the best practice for controlling a StatefulWidget\'s state outside of that Widgets State.

I have the following interface defined.

<

Answer 1

I do:

class StartupPage extends StatefulWidget {
  StartupPageState state;

  @override
  StartupPageState createState() {
    this.state = new StartupPageState();

    return this.state;
  }
}

class DetectedAnimationState extends State {

And outside just startupPage.state