为什么在这种特殊情况下，热重装无法正常工作？

Question

我一直在阅读有关颤振与热重装有关的一些问题。如果您在点击热重载按钮时（例如在Android Studio中）未执行您要修改的代码，则更改将不会发送到设备。

奇怪的是，为什么这段代码不强制热装：

导入“ package：flutter / material.dart”；

void main() {
  runApp(new MaterialApp(
      title: "My Flutter App",
      home: new Scaffold(
        appBar: new AppBar(
            title: new Text("My Flutter App"),
            backgroundColor: Colors.purple,
        ),
        body: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            new Text("Hello",textAlign: TextAlign.left),
            new Text("Pepe",textAlign: TextAlign.left),
            new Text("Antonio")
          ] ,
        ),
      ),
  ));
}

但此方法（相同的代码，只是将主页小部件移动到自定义小部件）有效：

import 'package:flutter/material.dart';

void main() {
  runApp(new MaterialApp(
      title: "My Flutter App",
      home: Home()
  ));
}


class Home extends StatelessWidget
{
  @override
  Widget build(BuildContext context)
  {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("My Flutter App"),
        backgroundColor: Colors.purple,
      ),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          new Text("Hello",textAlign: TextAlign.left),
          new Text("Pepe",textAlign: TextAlign.left),
          new Text("Antonio")
        ] ,
      ),
    );
  }
}