Dart 颤振/省道错误：中出现意外的标记0（无）_MyAppState@16036154.build

我在尝试执行此操作时遇到以下错误。奇怪的是，谷歌搜索这个错误消息并没有产生任何有用的见解

错误消息：

I/flutter ( 5472): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY 
╞═══════════════════════════════════════════════════════════
I/flutter ( 5472): The following _CompileTimeError was thrown building MyApp(dirty, state: _MyAppState#f8841):
I/flutter ( 5472): 'file:///Users/micah/MobileApps/flutter_test_1/lib/main.dart': error: Unexpected tag 0 (Nothing) in
I/flutter ( 5472): _MyAppState@16036154.build, expected a procedure, a constructor or a function node
I/flutter ( 5472):
I/flutter ( 5472): When the exception was thrown, this was the stack:
I/flutter ( 5472): #0      StatefulElement.build (package:flutter/src/widgets/framework.dart:3730:27)

import 'package:flutter/material.dart';

//    import './product_manager.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
      //  appBar: AppBar(
      //    title: Text('EasyList'),
      //  ),
      //  body: ProductManager(),
      ),
    );
  }
}

import 'package:flutter/material.dart';

class Products extends StatelessWidget {
  final List<String> products;

  Products(this.products);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: products
        .map(
          (element) => Card(
                child: Column(
                  children: <Widget>[
                    Image.asset('assets/food.jpg'),
                    Text(element)
                  ],
                ),
              ),
        )
        .toList()
      );
  }
}

import 'package:flutter/material.dart';

import './products.dart';

class ProductManager extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _ProductManagerState();
  }
}

class _ProductManagerState extends State<ProductManager> {
  List<String> _products = ['Food Tester'];

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Container(
          margin: EdgeInsets.all(10.0),
          child: RaisedButton(
            onPressed: () {
              setState(() {
                _products.add('Advanced Food Tester');
              });
            },
            child: Text('Add Product'),
          ),
        ),
        Products(_products)
      ],
    );
  }
}

main.dart文件：

I/flutter ( 5472): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY 
╞═══════════════════════════════════════════════════════════
I/flutter ( 5472): The following _CompileTimeError was thrown building MyApp(dirty, state: _MyAppState#f8841):
I/flutter ( 5472): 'file:///Users/micah/MobileApps/flutter_test_1/lib/main.dart': error: Unexpected tag 0 (Nothing) in
I/flutter ( 5472): _MyAppState@16036154.build, expected a procedure, a constructor or a function node
I/flutter ( 5472):
I/flutter ( 5472): When the exception was thrown, this was the stack:
I/flutter ( 5472): #0      StatefulElement.build (package:flutter/src/widgets/framework.dart:3730:27)

import 'package:flutter/material.dart';

//    import './product_manager.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
      //  appBar: AppBar(
      //    title: Text('EasyList'),
      //  ),
      //  body: ProductManager(),
      ),
    );
  }
}

import 'package:flutter/material.dart';

class Products extends StatelessWidget {
  final List<String> products;

  Products(this.products);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: products
        .map(
          (element) => Card(
                child: Column(
                  children: <Widget>[
                    Image.asset('assets/food.jpg'),
                    Text(element)
                  ],
                ),
              ),
        )
        .toList()
      );
  }
}

import 'package:flutter/material.dart';

import './products.dart';

class ProductManager extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _ProductManagerState();
  }
}

class _ProductManagerState extends State<ProductManager> {
  List<String> _products = ['Food Tester'];

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Container(
          margin: EdgeInsets.all(10.0),
          child: RaisedButton(
            onPressed: () {
              setState(() {
                _products.add('Advanced Food Tester');
              });
            },
            child: Text('Add Product'),
          ),
        ),
        Products(_products)
      ],
    );
  }
}

products.dart文件：

I/flutter ( 5472): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY 
╞═══════════════════════════════════════════════════════════
I/flutter ( 5472): The following _CompileTimeError was thrown building MyApp(dirty, state: _MyAppState#f8841):
I/flutter ( 5472): 'file:///Users/micah/MobileApps/flutter_test_1/lib/main.dart': error: Unexpected tag 0 (Nothing) in
I/flutter ( 5472): _MyAppState@16036154.build, expected a procedure, a constructor or a function node
I/flutter ( 5472):
I/flutter ( 5472): When the exception was thrown, this was the stack:
I/flutter ( 5472): #0      StatefulElement.build (package:flutter/src/widgets/framework.dart:3730:27)

import 'package:flutter/material.dart';

//    import './product_manager.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
      //  appBar: AppBar(
      //    title: Text('EasyList'),
      //  ),
      //  body: ProductManager(),
      ),
    );
  }
}

import 'package:flutter/material.dart';

class Products extends StatelessWidget {
  final List<String> products;

  Products(this.products);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: products
        .map(
          (element) => Card(
                child: Column(
                  children: <Widget>[
                    Image.asset('assets/food.jpg'),
                    Text(element)
                  ],
                ),
              ),
        )
        .toList()
      );
  }
}

import 'package:flutter/material.dart';

import './products.dart';

class ProductManager extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _ProductManagerState();
  }
}

class _ProductManagerState extends State<ProductManager> {
  List<String> _products = ['Food Tester'];

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Container(
          margin: EdgeInsets.all(10.0),
          child: RaisedButton(
            onPressed: () {
              setState(() {
                _products.add('Advanced Food Tester');
              });
            },
            child: Text('Add Product'),
          ),
        ),
        Products(_products)
      ],
    );
  }
}

导入“包装：颤振/材料.省道”；
类产品扩展了无状态小部件{
最终产品清单；
产品（本产品）；
@凌驾
小部件构建（构建上下文）{
返回列(
儿童：产品
.地图(
（元素）=>卡(
子：列(
儿童：[
Image.asset（'assets/food.jpg'），
文本（元素）
],
),
),
)
托利斯先生（）
);
}
}

product\u manager.dart文件：

I/flutter ( 5472): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY 
╞═══════════════════════════════════════════════════════════
I/flutter ( 5472): The following _CompileTimeError was thrown building MyApp(dirty, state: _MyAppState#f8841):
I/flutter ( 5472): 'file:///Users/micah/MobileApps/flutter_test_1/lib/main.dart': error: Unexpected tag 0 (Nothing) in
I/flutter ( 5472): _MyAppState@16036154.build, expected a procedure, a constructor or a function node
I/flutter ( 5472):
I/flutter ( 5472): When the exception was thrown, this was the stack:
I/flutter ( 5472): #0      StatefulElement.build (package:flutter/src/widgets/framework.dart:3730:27)

import 'package:flutter/material.dart';

//    import './product_manager.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
      //  appBar: AppBar(
      //    title: Text('EasyList'),
      //  ),
      //  body: ProductManager(),
      ),
    );
  }
}

import 'package:flutter/material.dart';

class Products extends StatelessWidget {
  final List<String> products;

  Products(this.products);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: products
        .map(
          (element) => Card(
                child: Column(
                  children: <Widget>[
                    Image.asset('assets/food.jpg'),
                    Text(element)
                  ],
                ),
              ),
        )
        .toList()
      );
  }
}

import 'package:flutter/material.dart';

import './products.dart';

class ProductManager extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _ProductManagerState();
  }
}

class _ProductManagerState extends State<ProductManager> {
  List<String> _products = ['Food Tester'];

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Container(
          margin: EdgeInsets.all(10.0),
          child: RaisedButton(
            onPressed: () {
              setState(() {
                _products.add('Advanced Food Tester');
              });
            },
            child: Text('Add Product'),
          ),
        ),
        Products(_products)
      ],
    );
  }
}

导入“包装：颤振/材料.省道”；
导入“/products.dart”；
类ProductManager扩展StatefulWidget{
@凌驾
状态createState（）{
返回_ProductManagerState（）；
}
}
类_ProductManagerState扩展状态{
清单_产品=[‘食品测试仪’]；
@凌驾
小部件构建（构建上下文）{
返回列(
儿童：[
容器(
保证金：所有边缘套（10.0），
孩子：升起按钮(
已按下：（）{
设置状态（）{
_添加（“高级食品检测仪”）；
});
},
子项：文本（“添加产品”），
),
),
产品（_产品）
],
);
}
}

单击“重新启动调试”修复了问题

我相信问题可能与我在不重新启动调试器的情况下从

StatefullWidget

更改为

无状态widget

有关。

单击“重新启动调试”修复了问题

---

我相信问题可能与我在未重新启动调试器的情况下从

StatefullWidget

更改为

StatefullWidget

有关。

导入在

main.dart

中是什么样子？切勿使用相对导入，如

import'/product\u manager.dart'在
main.dart
中-这会导致奇怪的问题-这是一个已知的问题，最终会得到解决。另外，
flatterclean
通常有助于解决奇怪的问题。导入在
main.dart
中是什么样子的？切勿使用相对导入，如
import'/product\u manager.dart'在
main.dart
中-这会导致奇怪的问题-这是一个已知的问题，最终会得到解决。另外，
flatterclean
通常有助于解决奇怪的问题。