重现步骤

1. 按 操作 按钮。
2. 检查 _widgetKey.currentState 在 actionHandler 中。

预期结果

_widgetKey 应具有有效的 currentState , currentWidget 值

实际结果

_widgetKey 对于 currentState 、 currentWidget 和其他字段具有空值

代码示例

代码示例

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyPage extends StatefulWidget {
  const MyPage({super.key});

  @override
  MyPageState createState() => MyPageState();
}

class MyPageState extends State<MyPage> {
  ListBody _widgets = const ListBody();
  final GlobalKey _widgetKey = GlobalKey();
  Widget inputWidget = const TextField();

  @override
  void initState() {
    setState(() {
      inputWidget = TextField(key: _widgetKey);
      _widgets = widgets(context);
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    var widget = Scaffold(
      body: ListView(
        children: [
          inputWidget,
          const Text("Widgets"),
          _widgets,
          TextButton(onPressed: actionHandler, child: const Text("Action")),
        ],
      ),
    );
    return widget;
  }

  void actionHandler() async {
    if (_widgetKey.currentState == null) {
      debugPrint("state is null");
    }
  }

  ListBody widgets(BuildContext context) {
    return ListBody(
        children: List.generate(18, (index) {
      return const TextField();
    }));
  }
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});
  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(widget.title),
      ),
      body: const Center(child: MyPage()),
    );
  }
}

截图或视频

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日志

日志

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Flutter Doctor 输出

Doctor 输出

flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 3.22.2, on Microsoft Windows [Version 10.0.22631.3880], locale uk-UA)
[√] Windows Version (Installed version of Windows is version 10 or higher)
[√] Android toolchain - develop for Android devices (Android SDK version 33.0.0)
[√] Chrome - develop for the web
[√] Visual Studio - develop Windows apps (Visual Studio Community 2022 17.8.3)
[√] Android Studio (version 2021.2)
[√] IntelliJ IDEA Community Edition (version 2023.1)
[√] VS Code (version 1.91.1)
[√] Connected device (3 available)
[√] Network resources

• No issues found!