为什么StatefulWidget的路由创建失败？

Question

我正在尝试使用StatefulWidget创建一个路由。

错误：

I/flutter (23141): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (23141): The following assertion was thrown building
I/flutter (23141): _OverlayEntry-[LabeledGlobalKey<_OverlayEntryState>#3e9ee](dirty, state: _OverlayEntryState#7b90c):
I/flutter (23141): The builder for route "/" returned null.
I/flutter (23141): Route builders must never return null.

码：

routes:<String,WidgetBuilder>{
        "/":(_)=>new RouteHome(title: 'Flutter Demo Home Page'),
        ...

class RouteHome extends StatefulWidget {
  RouteHome({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

查询：

• 为什么不允许StatefulWidget？

---

问题：如果更改了窗口小部件的基类，则路由的热重新加载失败（StatefulWidget < - > StatelessWidget）。

Answer 1

热重新加载仅用于最小的UI更改。

礼貌：“这不是问题，使用热重新加载来进行UI中的最小更改。通常，在创建新类时需要完全重启。” - @aziza