Flutter Video Player的initState（）方法问题

Question

我的代码中initState（）方法的位置似乎有问题。

   class WalkThrough extends StatefulWidget {
  @override
  _WalkThroughState createState() => _WalkThroughState();
}

class _WalkThroughState extends State<WalkThrough> {
  VideoPlayerController _controller;

没有这一行代码，当前将无法运行代码。

  noSuchMethod(Invocation i) => super.noSuchMethod(i);

  @override

以下initState（）方法是否应该放在其他位置？

  void initState() {
    super.initState();
    // Pointing the video controller to our local asset.
    _controller = VideoPlayerController.asset("assets/coffee.mp4")
      ..initialize().then((_) {
        // Once the video has been loaded we play the video and set looping to true.
        _controller.play();
        _controller.setLooping(true);
        // Ensure the first frame is shown after the video is initialized.
        setState(() {});
      });

    Widget build(BuildContext context) {
      return Scaffold(
        body: Stack(
          children: <Widget>[
            SizedBox.expand(
              child: FittedBox(
                fit: BoxFit.fill,
                child: SizedBox(
                  width: _controller.value.size?.width ?? 0,
                  height: _controller.value.size?.height ?? 0,
                  child: VideoPlayer(_controller),
                ),
              ),
            ),