随便写了个demo, 修改widget的颜色, 开启hot reload 发现并没有什么改变. 只有hot restart才有反应

import 'package:flutter/material.dart';

void main() {
  runApp(build());
}

Widget build() {
  return MaterialApp(
      home: Scaffold(
    body: Center(
      child: ConstrainedBox(
        constraints: BoxConstraints.tight(const Size(100, 100)),
        child: Container(
          color: Colors.yellow,
          width: 30,
          height: 30,
        ),
      ),
    ),
  ));
}

跟记忆中的好像有点不太一样
那热加载(hot reload)和热重启(hot restart)有什么区别呢?

·Hot reload loads code changes into the VM and re-builds the widget tree, preserving the app state; it doesn't rerun main( ) or initState().(command\ in Intellij and Android Studio,^F5 in VSCode)

·Hot restart loads code changes into the VM, and restarts the Flutter app, losing the app state. (↑command\ in IntelliJ and Android Studio,↑commandF5 in VSCode)

热加载(hot reload)加载代码修改到虚拟机, 重新build了widget树, 保留了app状态, 它不会重走main方法和initState方法(但会走build方法)

热重启(hot restart)加载代码修改到虚拟机, 重启了Flutter app, 丢失了app状态, 它会重走main方法

那么回到我上面的demo, 我这个widget是在main里面加载的, 但是hot reload并不会重走main, 所以改变是不会生效的. 但当你的改变在build方法里时, 就可以生效

PS: VS上的快捷键

Hot reload command + \ (Android Studio), control + F5 (VS Code)

Hot reload shift + command + \ (Android Studio), shift + control + F5 (VS Code)

这里有一个类似的问题