Question

我不明白为什么会出现此错误：我正在遵循安吉拉（Angela）的Flutter课程，并且已经与她的代码进行了核对，但我真的发现没有任何区别... widget.locationWeather的值不为null ...我不明白为什么我会得到这个错误...感谢您的帮助，我非常感谢收到的任何帮助！


════════ Exception caught by widgets library ═══════════════════════════════════════════════════════

The following _TypeError was thrown building Builder:

type 'String' is not a subtype of type 'int' of 'index'



The relevant error-causing widget was:

  MaterialApp file:///Volumes/Mac%20Mini/App%20Development/Coding/Flutter%20Development/clima-flutter/lib/main.dart:9:12

When the exception was thrown, this was the stack:

#0      _LocationScreenState.updateUI (package:clima/screens/location_screen.dart:25:30)

#1      _LocationScreenState.initState (package:clima/screens/location_screen.dart:21:5)

#2      StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4640:58)

#3      ComponentElement.mount (package:flutter/src/widgets/framework.dart:4476:5)

...     Normal element mounting (4 frames)



════════════════════════════════════════════════════════════════════════════════════════════════════

import 'package:flutter/material.dart';
import 'package:clima/utilities/constants.dart';
 
class LocationScreen extends StatefulWidget {
  LocationScreen({this.locationWeather});
 
  final locationWeather;
 
  @override
  _LocationScreenState createState() => _LocationScreenState();
}
 
class _LocationScreenState extends State<LocationScreen> {
  double temperature;
  int condition;
  String cityName;
 
  @override
  void initState() {
    super.initState();
    updateUI(widget.locationWeather);
  }
 
  void updateUI(dynamic weatherData) {
    temperature = weatherData['main']['temp'];
    condition = weatherData['weather'][0]['id'];
    cityName = weatherData['name'];
    print(temperature);
  }
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        decoration: BoxDecoration(
          image: DecorationImage(
            image: AssetImage('images/location_background.jpg'),
            fit: BoxFit.cover,
            colorFilter: ColorFilter.mode(
                Colors.white.withOpacity(0.8), BlendMode.dstATop),
          ),
        ),
        constraints: BoxConstraints.expand(),
        child: SafeArea(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: <Widget>[
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: <Widget>[
                  FlatButton(
                    onPressed: () {},
                    child: Icon(
                      Icons.near_me,
                      size: 50.0,
                    ),
                  ),
                  FlatButton(
                    onPressed: () {},
                    child: Icon(
                      Icons.location_city,
                      size: 50.0,
                    ),
                  ),
                ],
              ),
              Padding(
                padding: EdgeInsets.only(left: 15.0),
                child: Row(
                  children: <Widget>[
                    Text(
                      '32°',
                      style: kTempTextStyle,
                    ),
                    Text(
                      '☀️',
                      style: kConditionTextStyle,
                    ),
                  ],
                ),
              ),
              Padding(
                padding: EdgeInsets.only(right: 15.0),
                child: Text(
                  "It's ? time in San Francisco!",
                  textAlign: TextAlign.right,
                  style: kMessageTextStyle,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

我知道updateUI方法中的三行是有问题的，但是将温度，条件和cityName的数据类型更改为var或dynamic并没有用，并且抛出了相同的错误！ / p>

Flutter（_TypeError）无法理解为什么会发生

0 个答案: