Flutter：FutureBuilder类型“ FormatException”不是类型“ Widget”的子类型
我正在做与天气预报有关的部分。
在他那天，我问如何获取json列表中的数据： Flutter: Get data from a list of json
我认为错误是关于----> ]的json
当我尝试显示数据时，出现错误。我希望能解决这个问题，感谢您的帮助。
ScreenShot
JSON：
{
"metcheckData": {
"forecastLocation": {
"forecast": [
{
"temperature": "18",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4656",
"uvIndex": "0",
"totalcloud": "8",
"lowcloud": "8",
"medcloud": "0",
"highcloud": "0",
"humidity": "84",
"windspeed": "9",
"meansealevelpressure": "1018.02",
"windgustspeed": "11",
"winddirection": "28.7724",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "3",
"weekday": "Tuesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-19T23:00:00.00"
},
{
"temperature": "18",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4663",
"uvIndex": "0",
"totalcloud": "8",
"lowcloud": "8",
"medcloud": "0",
"highcloud": "0",
"humidity": "85",
"windspeed": "9",
"meansealevelpressure": "1018.26",
"windgustspeed": "11",
"winddirection": "29.4946",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T00:00:00.00"
},
{
"temperature": "18",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4666",
"uvIndex": "0",
"totalcloud": "8",
"lowcloud": "8",
"medcloud": "0",
"highcloud": "0",
"humidity": "86",
"windspeed": "9",
"meansealevelpressure": "1018.18",
"windgustspeed": "10",
"winddirection": "30.0925",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T01:00:00.00"
},
{
"temperature": "18",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4668",
"uvIndex": "0",
"totalcloud": "11",
"lowcloud": "11",
"medcloud": "0",
"highcloud": "0",
"humidity": "87",
"windspeed": "8",
"meansealevelpressure": "1017.79",
"windgustspeed": "10",
"winddirection": "30.761",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T02:00:00.00"
},
{
"temperature": "17",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4671",
"uvIndex": "0",
"totalcloud": "12",
"lowcloud": "12",
"medcloud": "0",
"highcloud": "0",
"humidity": "87",
"windspeed": "8",
"meansealevelpressure": "1017.36",
"windgustspeed": "9",
"winddirection": "31.0844",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T03:00:00.00"
},
{
"temperature": "17",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4673",
"uvIndex": "0",
"totalcloud": "11",
"lowcloud": "11",
"medcloud": "0",
"highcloud": "0",
"humidity": "88",
"windspeed": "8",
"meansealevelpressure": "1017.04",
"windgustspeed": "9",
"winddirection": "31.4161",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T04:00:00.00"
},
{
"temperature": "17",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4671",
"uvIndex": "0",
"totalcloud": "11",
"lowcloud": "11",
"medcloud": "0",
"highcloud": "0",
"humidity": "89",
"windspeed": "7",
"meansealevelpressure": "1016.89",
"windgustspeed": "9",
"winddirection": "31.2326",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T05:00:00.00"
},
{
"temperature": "17",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4668",
"uvIndex": "0",
"totalcloud": "10",
"lowcloud": "10",
"medcloud": "0",
"highcloud": "0",
"humidity": "91",
"windspeed": "8",
"meansealevelpressure": "1017.04",
"windgustspeed": "9",
"winddirection": "30.2947",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T06:00:00.00"
},
{
"temperature": "17",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4664",
"uvIndex": "0",
"totalcloud": "9",
"lowcloud": "9",
"medcloud": "0",
"highcloud": "0",
"humidity": "92",
"windspeed": "8",
"meansealevelpressure": "1017.35",
"windgustspeed": "10",
"winddirection": "29.0404",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T07:00:00.00"
},
{
"temperature": "17",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4664",
"uvIndex": "0",
"totalcloud": "16",
"lowcloud": "16",
"medcloud": "0",
"highcloud": "0",
"humidity": "91",
"windspeed": "9",
"meansealevelpressure": "1017.77",
"windgustspeed": "10",
"winddirection": "27.9231",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T08:00:00.00"
},
{
"temperature": "18",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4673",
"uvIndex": "1",
"totalcloud": "32",
"lowcloud": "32",
"medcloud": "0",
"highcloud": "0",
"humidity": "86",
"windspeed": "9",
"meansealevelpressure": "1018.05",
"windgustspeed": "11",
"winddirection": "25.3295",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T09:00:00.00"
},
{
"temperature": "18",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4687",
"uvIndex": "2",
"totalcloud": "38",
"lowcloud": "38",
"medcloud": "0",
"highcloud": "0",
"humidity": "82",
"windspeed": "9",
"meansealevelpressure": "1018.31",
"windgustspeed": "10",
"winddirection": "22.0118",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T10:00:00.00"
},
{
"temperature": "19",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4702",
"uvIndex": "3",
"totalcloud": "36",
"lowcloud": "36",
"medcloud": "0",
"highcloud": "0",
"humidity": "76",
"windspeed": "9",
"meansealevelpressure": "1018.56",
"windgustspeed": "10",
"winddirection": "18.4385",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T11:00:00.00"
},
{
"temperature": "20",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4712",
"uvIndex": "4",
"totalcloud": "31",
"lowcloud": "31",
"medcloud": "0",
"highcloud": "0",
"humidity": "72",
"windspeed": "9",
"meansealevelpressure": "1018.79",
"windgustspeed": "9",
"winddirection": "14.9684",
"windletter": "NNE",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T12:00:00.00"
},
{
"temperature": "20",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4722",
"uvIndex": "5",
"totalcloud": "26",
"lowcloud": "26",
"medcloud": "0",
"highcloud": "0",
"humidity": "69",
"windspeed": "9",
"meansealevelpressure": "1018.9",
"windgustspeed": "8",
"winddirection": "12.5729",
"windletter": "W",
"icon": "FA",
"iconName": "Fair",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T13:00:00.00"
},
{
"temperature": "21",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4739",
"uvIndex": "10",
"totalcloud": "1",
"lowcloud": "1",
"medcloud": "0",
"highcloud": "0",
"humidity": "68",
"windspeed": "9",
"meansealevelpressure": "1018.83",
"windgustspeed": "8",
"winddirection": "10.6461",
"windletter": "N",
"icon": "SU",
"iconName": "Sunny",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T14:00:00.00"
},
{
"temperature": "21",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4765",
"uvIndex": "10",
"totalcloud": "1",
"lowcloud": "1",
"medcloud": "0",
"highcloud": "0",
"humidity": "67",
"windspeed": "9",
"meansealevelpressure": "1018.59",
"windgustspeed": "8",
"winddirection": "9.82178",
"windletter": "N",
"icon": "SU",
"iconName": "Sunny",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T15:00:00.00"
},
{
"temperature": "21",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4797",
"uvIndex": "10",
"totalcloud": "1",
"lowcloud": "1",
"medcloud": "0",
"highcloud": "0",
"humidity": "67",
"windspeed": "9",
"meansealevelpressure": "1018.34",
"windgustspeed": "8",
"winddirection": "9.66212",
"windletter": "N",
"icon": "SU",
"iconName": "Sunny",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T16:00:00.00"
},
{
"temperature": "21",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4826",
"uvIndex": "9",
"totalcloud": "1",
"lowcloud": "1",
"medcloud": "0",
"highcloud": "0",
"humidity": "68",
"windspeed": "9",
"meansealevelpressure": "1017.98",
"windgustspeed": "8",
"winddirection": "8.49407",
"windletter": "N",
"icon": "SU",
"iconName": "Sunny",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T17:00:00.00"
},
{
"temperature": "20",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4844",
"uvIndex": "9",
"totalcloud": "1",
"lowcloud": "1",
"medcloud": "0",
"highcloud": "0",
"humidity": "70",
"windspeed": "9",
"meansealevelpressure": "1017.81",
"windgustspeed": "9",
"winddirection": "8.70691",
"windletter": "N",
"icon": "SU",
"iconName": "Sunny",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "D",
"utcTime": "2018-06-20T18:00:00.00"
},
{
"temperature": "20",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4857",
"uvIndex": "8",
"totalcloud": "1",
"lowcloud": "1",
"medcloud": "0",
"highcloud": "0",
"humidity": "72",
"windspeed": "10",
"meansealevelpressure": "1017.93",
"windgustspeed": "10",
"winddirection": "10.5324",
"windletter": "N",
"icon": "SU",
"iconName": "Sunny",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T19:00:00.00"
},
{
"temperature": "19",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4872",
"uvIndex": "2",
"totalcloud": "1",
"lowcloud": "1",
"medcloud": "0",
"highcloud": "0",
"humidity": "74",
"windspeed": "10",
"meansealevelpressure": "1018.25",
"windgustspeed": "11",
"winddirection": "13.7294",
"windletter": "NNE",
"icon": "SU",
"iconName": "Sunny",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T20:00:00.00"
},
{
"temperature": "19",
"dewpoint": "15",
"rain": "0",
"freezinglevel": "4889",
"uvIndex": "1",
"totalcloud": "1",
"lowcloud": "1",
"medcloud": "0",
"highcloud": "0",
"humidity": "78",
"windspeed": "11",
"meansealevelpressure": "1018.64",
"windgustspeed": "13",
"winddirection": "17.2073",
"windletter": "NNE",
"icon": "SU",
"iconName": "Sunny",
"chanceofrain": "0",
"chanceofsnow": "0",
"dayOfWeek": "4",
"weekday": "Wednesday",
"sunrise": "6:57",
"sunset": "19:04",
"dayOrNight": "N",
"utcTime": "2018-06-20T21:00:00.00"
},
],
"continent": "",
"country": "",
"location": "28.0/-15.6",
"latitude": 28.0,
"longitude": -15.6,
"timezone": 1
}
},
"feedCreation": "2018-06-19T23:05:19.00",
"feedCreator": "Metcheck.com",
"feedModel": "GHX2",
"feedModelRun": "12Z",
"feedModelRunInitialTime": "2018-06-19T12:00:00.00",
"feedResolution": "0.01"
}
ViewWeather
import 'dart:async';
import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:flutter/material.dart';
class _ViewWeatherState extends State<ViewWeather> {
Future<List<Post>> fetchPosts() async {
http.Response response = await http.get('http://ws1.metcheck.com/ENGINE/v9_0/json.asp?lat=28&lon=-15.6&lid=62228&Fc=No');
var responseJson = json.decode(response.body);
return (responseJson['metcheckData']['forecastLocation']['forecast'] as List).map((p) => Post.fromJson(p)).toList();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: new AppBar(
title: new Text(widget.title),
backgroundColor: Colors.blue[900],
centerTitle: true,
),
body: new Container(
child: new ListView(
children: <Widget>[
new FutureBuilder<List<Post>>(
future: fetchPosts(),
builder: (context, snapshot) {
if (snapshot.hasData){
List<Post> posts = snapshot.data;
return new Column(
children: posts.map((post) => new Column(
children: <Widget>[
new Text(post.temperature),
],
)).toList()
);
}
else if(snapshot.hasError)
{
return snapshot.error;
}
return new Center(
child: new Column(
children: <Widget>[
new Padding(padding: new EdgeInsets.all(50.0)),
new CircularProgressIndicator(),
],
),
);
},
),
],
)
),
);
}
}
发布
class Post {
final String temperature, rain, humidity, sunrise, sunset, updateDate;
Post({
this.temperature,
this.rain,
this.humidity,
this.sunrise,
this.sunset,
this.updateDate,
});
factory Post.fromJson(Map<String, dynamic> json) {
return new Post(
temperature: json['temperature'] as String,
rain: json['rain'] as String,
humidity: json['humidity'] as String,
sunrise: json['sunrise'] as String,
sunset: json['sunset'] as String,
updateDate: json['utcTime'] as String,
);
}
}
2 个答案:
答案 0 :(得分：2)
JSON的第621行还有一个逗号。在最后一个utcTime之后，在}和]之间，几乎到最后。下面重复以供参考。
"utcTime": "2018-06-20T21:00:00.00"
}, <--- OOPS
],
"continent": "",
"country": "",
"location": "28.0/-15.6",
"latitude": 28.0,
"longitude": -15.6,
"timezone": 1
}
},
"feedCreation": "2018-06-19T23:05:19.00",
"feedCreator": "Metcheck.com",
"feedModel": "GHX2",
"feedModelRun": "12Z",
"feedModelRunInitialTime": "2018-06-19T12:00:00.00",
"feedResolution": "0.01"
}
答案 1 :(得分：0)
问题出在两个地方：
1）您的JSON无效
2）问题1）使您的解析失败并触发：
else if(snapshot.hasError)
{
return snapshot.error;
}
您可以猜测error不是一个Widget，它导致FormatException
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