Flutter JSON无法正确读取 [英] Flutter JSON not reading correctly

问题描述

这可能需要一段时间...
我一直在尝试获取Dart / Flutter代码以从 BlockChainTicker （特别是我想从AUD行查看所有内容），并将其保留在调试控制台中。这样做时，我会从控制台获得此错误

this might take a while... I've been trying to get my Dart/Flutter code to return data from BlockChainTicker (Specifically I would like to see everything from the AUD line) and leave this in the Debug Console. When I do so, I get this error back from the Console

E/flutter ( 8656): [ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
E/flutter ( 8656): type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'List' where
E/flutter ( 8656):   _InternalLinkedHashMap is from dart:collection
E/flutter ( 8656):   String is from dart:core
E/flutter ( 8656):   List is from dart:core

我的代码似乎很成熟，但是我只有大约一周的使用这种语言的经验，所以感谢您的耐心等待

My code might seem amature but I only have about a weeks experience in this language, so thanks for any patience you might take in reading over this.

import 'dart:async';
import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;



class First extends StatefulWidget {
  @override
  HomePageState createState() => new HomePageState();
}

class HomePageState extends State<First> {

  List data;

  Future<String> getData() async {
    var response = await http.get(
      Uri.encodeFull("http://blockchain.info/ticker"),
      headers: {
        "Accept": "application/json"
      }
    );
    data = JSON.decode(response.body);
    print(data[1]["AUD"]);

    return "Success!";
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Center(
        child: new RaisedButton(
          child: new Text("Get data"),
          onPressed: getData,
        ),
      ),
    );
  }
}

推荐答案

json的顶层是一个地图（不是列表-在json中，列表用括号括起来）

The top level of your json is a map (not a list - in json, lists are enclosed in brackets)

{
  "USD" : {"15m" : 7492.85, "last" : 7492.85, "buy" : 7492.85, "sell" : 7492.85, "symbol" : "$"},
  "AUD" : {"15m" : 9899.28, "last" : 9899.28, "buy" : 9899.28, "sell" : 9899.28, "symbol" : "$"},
  "BRL" : {"15m" : 28214.31, "last" : 28214.31, "buy" : 28214.31, "sell" : 28214.31, "symbol" : "R$"},

因此更改：

print(data[1]["AUD"]);

到

print(data["AUD"]); // prints the whole AUD map
print(data['AUD']['last']); // prints the AUD 'last' double

String isoCode = 'AUD';
print('$isoCode -> ${data[isoCode]}');

这篇关于Flutter JSON无法正确读取的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！