flutter - JSON 文件未在 Flutter 上加载

Question

我是 Flutter 的新手，目前我的 JSON 文件内容无法填充到我的模拟器中。它没有显示错误，但没有显示。如果我将内容直接包含在我的代码块中，它就可以正常工作。我无法发现问题。

以下是我的代码:

main.dart 代码

import 'package:emailapp/messagelist.dart';
import 'package:flutter/material.dart';


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

class EmailApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(

        primarySwatch: Colors.green
      ),
      home: MessageList(title: 'Muss Mailer APP'),
    );
  }
}

消息列表.dart

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

class MessageList extends StatefulWidget{

  final String title;

  const MessageList({Key key, this.title}) : super(key: key);

@override
State<StatefulWidget> createState()=>_MessageListState();
}

class _MessageListState extends State<MessageList>{
var messages=const [];

Future loadMessageList()  async{
  var content=await rootBundle.loadString('data/message.json');
  print(content);
  var collection=json.decode(content);

setState(() {
 messages=collection; 
});
}
void initstate() {
  loadMessageList();
  super.initState();
}
   Widget build(BuildContext context) {
     return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),

    body: ListView.separated(
      separatorBuilder: (context,index)=>Divider(),

    itemCount: messages.length,

  itemBuilder: (BuildContext context, int index){
    var message=messages[index];

    return ListTile(
      isThreeLine: true,
      leading: CircleAvatar( child: Text('AJ'),),
      title: Text(message['subject']),
      subtitle: Text(message['body'],maxLines: 2, overflow: TextOverflow.ellipsis,),

      ) ;
  },
),


    );
  }

}

消息.json

   [ {
        "subject":"My First Message",
  "body":"Hello Form the other side of life fellas.. and happy to meet you guys"

      },
      {
        "subject":"My Second Message",
  "body":"Hello Form the other side of life fellas.. and happy to meet you guys"

      },
      {
        "subject":"My Third Message",
  "body":"Hello Form the other side of life fellas.. and happy to meet you guys"

      },
      {
        "subject":"My Fourth Message",
  "body":"Hello Form the other side of life fellas.. and happy to meet you guys"

      },
      {
        "subject":"My Fifth Message",
  "body":"Hello Form the other side of life fellas.. and happy to meet you guys"

      },
      {
        "subject":"My Sixth Message",
  "body":"Hello Form the other side of life fellas.. and happy to meet you guys"

      }]

发布规范.yaml

  assets:
  #  - images/a_dot_burr.jpeg
  #  - images/a_dot_ham.jpeg
    - data/message.json

Answer 1

这只是一个拼写错误。这不是 initstate .其initState ( S 是大写字母)。

void initState() {
  loadMessageList();
  super.initState();
}