Question

我是 flutter 新手，我仍在学习基础知识，但我遇到了这个异常：setState() 或 markNeedsBuild() 和异常：失败的断言：第 4134 行 pos 12：'!_debugLocked'：不是真的 //第一个代码是主文件，第二个是抽屉文件，其中任何一个都没有错误

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  Map<String, bool> _filters = {
    'gluten': false,
    'lactose': false,
    'vegan': false,
    'vegetarian': false,
  };
  List<Meal> _availableMeals = DUMMY_MEALS;
  List<Meal> _favoriteMeals = [];

  void _setFilters(Map<String, bool> filterData) {
    if (!mounted) return;
    setState(() {
      _filters = filterData;

      _availableMeals = DUMMY_MEALS.where((meal) {
        if (_filters['gluten'] == true && !meal.isGlutenFree) {
          return false;
        }
        if (_filters['lactose'] = true && !meal.isLactoseFree) {
          return false;
        }
        if (_filters['vegan'] == true && !meal.isVegan) {
          return false;
        }
        if (_filters['vegetarian'] == true && !meal.isVegetarian) {
          return false;
        }
        return true;
      }).toList();
    });
  }

  void _toggleFavorite(String mealId) {
    final existingIndex =
        _favoriteMeals.indexWhere((meal) => meal.id == mealId);
    if (existingIndex >= 0) {
      if (!mounted) return;
      setState(() {
        _favoriteMeals.removeAt(existingIndex);
      });
    } else {
      if (!mounted) return;
      setState(() {
        _favoriteMeals.add(
          DUMMY_MEALS.firstWhere((meal) => meal.id == mealId),
        );
      });
    }
  }

  bool _isMealFavorite(String id) {
    return _favoriteMeals.any((meal) => meal.id == id);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'DeliMeals',
      theme: ThemeData(
        primarySwatch: Colors.pink,
        accentColor: Colors.amber,
        canvasColor: Color.fromRGBO(255, 254, 229, 1),
        fontFamily: 'Raleway',
        textTheme: ThemeData.light().textTheme.copyWith(
            bodyText2: TextStyle(
              color: Color.fromRGBO(20, 51, 51, 1),
            ),
            bodyText1: TextStyle(
              color: Color.fromRGBO(20, 51, 51, 1),
            ),
            headline6: TextStyle(
              fontSize: 20,
              fontFamily: 'RobotoCondensed',
              fontWeight: FontWeight.bold,
            )),
      ),
      // home: CategoriesScreen(),
      initialRoute: '/', // default is '/'
      routes: {
        '/': (ctx) => TabsScreen(_favoriteMeals),
        CategoryMealsScreen.routeName: (ctx) =>
            CategoryMealsScreen(_availableMeals),
        MealDetailScreen.routeName: (ctx) =>
            MealDetailScreen(_toggleFavorite, _isMealFavorite),
        FiltersScreen.routeName: (ctx) => FiltersScreen(_filters, _setFilters),
      },
      onGenerateRoute: (settings) {
        print(settings.arguments);
        // if (settings.name == '/meal-detail') {
        //   return ...;
        // } else if (settings.name == '/something-else') {
        //   return ...;
        // }
        // return MaterialPageRoute(builder: (ctx) => CategoriesScreen(),);
      },
      onUnknownRoute: (settings) {
        return MaterialPageRoute(
          builder: (ctx) => CategoriesScreen(),
        );
      },
    );
  }
}  ```


    class MainDrawer extends StatelessWidget {
      
      Widget buildListTile(String title, IconData icon, Function tapHandler) {
        return ListTile(
          leading: Icon(
            icon,
            size: 26,
          ),
          title: Text(
            title,
            style: TextStyle(
              fontFamily: 'RobotoCondensed',
              fontSize: 24,
              fontWeight: FontWeight.bold,
            ),
          ),
          onTap: tapHandler(),
        );
      }
    
      @override
      Widget build(BuildContext context) {
        return Drawer(
          child: Column(
            children: <Widget>[
              Container(
                height: 120,
                width: double.infinity,
                padding: EdgeInsets.all(20),
                alignment: Alignment.centerLeft,
                color: Theme.of(context).accentColor,
                child: Text(
                  'Cooking Up!',
                  style: TextStyle(
                      fontWeight: FontWeight.w900,
                      fontSize: 30,
                      color: Theme.of(context).primaryColor),
                ),
              ),
              SizedBox(
                height: 20,
              ),
              buildListTile('Meals', Icons.restaurant, () {
                Navigator.of(context).pushReplacementNamed('/');
              }),
              buildListTile('Filters', Icons.settings, () {
                Navigator.of(context).pushReplacementNamed(FiltersScreen.routeName);
              }),
            ],
          ),
        );
      }
    }

Error:

    exception:Failed assertion: line 4134 pos 12: '!_debugLocked': is not true

Answer 1

转到您的 tapHandler() 函数。查找 setState，然后在它之前输入：

if(!mounted) return;
setState((....etc

这将在执行 setState 之前检查小部件是否已安装，这将消除您的错误。

获取异常：setState() 或 markNeedsBuild()

1 个答案: