参数类型“void Function(Map<String, bool>)”不能分配给参数类型“Map<String, bool>”

Posted 2023-02-23

【中文标题】参数类型“void Function(Map<String, bool>)”不能分配给参数类型“Map<String, bool>”

【英文标题】：The argument type 'void Function(Map<String, bool>)' can't be assigned to the parameter type 'Map<String, bool>'

【发布时间】：2021-11-28 21:54:51

【问题描述】：

我正在尝试将过滤器发送到过滤器屏幕，但出现错误。

参数类型“void Function(Map)”不能分配给参数类型“Map”。

主屏幕代码

import 'package:flutter/material.dart';
import 'package:meal_app/dummy.dart';
import 'package:meal_app/screens/bottom_navigation.dart';
import 'package:meal_app/screens/catagory_item_screen.dart';
import 'package:meal_app/screens/categorise_screen.dart';
import 'package:meal_app/screens/filters_screen.dart';
import 'package:meal_app/screens/homescreen.dart';
import 'package:meal_app/screens/meal_item_details.dart';
import 'package:meal_app/widgets/meal.dart';

void main() 
  runApp(MyApp());


class MyApp extends StatefulWidget 
  // This widget is the root of your application.
  @override
  State<MyApp> createState() => _MyAppState();


class _MyAppState extends State<MyApp> 
  Map<String, bool> _filter = 
    'gluton': false,
    'lactose': false,
    "vrgan": false,
    "vegetarian": false
  ;
  List<Meal> _availablemeal = DUMMY_MEALS;
  void _applyfilter(Map<String, bool> filterData) 
    setState(() 
      _filter = filterData;
      _availablemeal = DUMMY_MEALS.where((meals) 
        if (_filter['gluton']! && !meals.isGlutenFree) 
        if (_filter['lactose']! && !meals.isLactoseFree) 
          return false;
        
        if (_filter['vrgan']! && !meals.isVegan) 
          return false;
        
        if (_filter['vegetarian']! && !meals.isVegetarian) 
          return false;
        
        return true;
      ).toList();
    );
  

  @override
  Widget build(BuildContext context) 
    return MaterialApp(
      title: 'Meal App',
      theme: ThemeData(
        primarySwatch: Colors.pink,
        accentColor: Colors.amber,
        canvasColor: Color.fromRGBO(255, 255, 255, 1),
        fontFamily: 'Raleway',
        textTheme: ThemeData.light().textTheme.copyWith(
              bodyText1: TextStyle(
                color: Color.fromRGBO(20, 50, 51, 1),
              ),
              bodyText2: TextStyle(color: Color.fromRGBO(20, 50, 51, 1)),
              subtitle1: TextStyle(
                  fontSize: 20,
                  fontWeight: FontWeight.bold,
                  fontFamily: "RobotoCondensed"),
            ),
      ),
      initialRoute: '/',
      routes: 
        '/': (ctx) => BottomNavigation(),
        CatagoryItemScreen.routes: (ctx) => CatagoryItemScreen(_availablemeal),
        MealDetails.routs: (ctx) => MealDetails(),
        FiltersScreen.routeName: (ctx) => FiltersScreen(_filter, _applyfilter),
      ,
    );
  

当我使用 final VoidCallBack 时，它在 main.dart 中没有出现错误，但在 onPressed:widget.applyfilter(selectedfilter); 中出现错误，然后我将 VoidCallBack 替换为 Function(Map) 然后它开始在 main.dart 代码中出现错误。

过滤屏幕

import 'package:flutter/material.dart';
import 'package:meal_app/widgets/drawer.dart';

class FiltersScreen extends StatefulWidget 
  final Function(Map) applyfilter;
  final Map<String, bool> currentfilter;
  FiltersScreen(this.applyfilter, this.currentfilter);
  static const routeName = '/filter';

  @override
  State<FiltersScreen> createState() => _FiltersScreenState();


class _FiltersScreenState extends State<FiltersScreen> 
  Widget _buildSwitchTile(String title, String subTitle, var currentVal,
      Function(bool) nextQuestion) 
    return SwitchListTile(
      title: Text(title),
      subtitle: Text(subTitle),
      value: currentVal,
      activeColor: Colors.redAccent,
      onChanged: nextQuestion,
    );
  

  var isGlutenFree = false;
  var isLactoseFree = false;
  var isVegan = false;
  var isVegetarian = false;
  @override
  Widget build(BuildContext context) 
    return Scaffold(
      appBar: AppBar(
        title: Text("Filter Screen"),
        actions: [
          IconButton(
              icon: Icon(Icons.save),
              onPressed: () 
                final selectedfilter = 
                  'gluton': isGlutenFree,
                  'lactose': isLactoseFree,
                  "vrgan": isVegan,
                  "vegetarian": isVegetarian
                ;
                widget.applyfilter(selectedfilter);
              )
        ],
      ),
      drawer: MainDrawer(),
      body: Column(children: [
        Container(
          margin: EdgeInsets.all(20),
          child: Text(
            "Adjust your filters here",
            style: TextStyle(fontWeight: FontWeight.w900, fontSize: 26),
          ),
        ),
        Expanded(
            child: ListView(
          children: [
            _buildSwitchTile(
                "Glutan-Free", "only include Glutan-Free meal", isGlutenFree,
                (newValue) 
              setState(() 
                isGlutenFree = newValue;
              );
            ),
            _buildSwitchTile(
                "Lactose-Free", "only include Lactose-Free meal", isLactoseFree,
                (newValue) 
              setState(() 
                isLactoseFree = newValue;
              );
            ),
            _buildSwitchTile(
                "Vegan-Free", "only include Vegan-Free meal", isVegan,
                (newValue) 
              setState(() 
                isVegan = newValue;
              );
            ),
            _buildSwitchTile("Vegetarian-Free",
                "only include Vegetarian-Free meal", isVegetarian, (newValue) 
              setState(() 
                isVegetarian = newValue;
              );
            ),
          ],
        ))
      ]),
    );
  

【参考方案1】：

您以错误的顺序传递参数。切换它们：

FiltersScreen.routeName: (ctx) => FiltersScreen(_applyfilter, _filter)

同时在您的过滤器屏幕中定义匹配的地图类型：

final Function(Map<String, bool>) applyfilter;

（否则在修正参数顺序后您会收到另一条错误消息）