Question

我正在尝试从json文件制作Listview。但是我每次都会收到此错误。我已经尝试了所有可能的解决方案，但无法使错误消失。请帮我解决问题。

我是Flutter的初学者

我的代码：

import 'dart:convert';
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:practising/screens/details.dart';

class Home extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return HomeWidgets();
  }
}

class HomeWidgets extends State<Home> {
  Future<List<User>> loadJson() async {
    var jsonString = await rootBundle.loadString('assets/jsonFile.json');
    var temp = json.decode(jsonString);

    List<User> users = [];

    for (var u in temp) {
      User user = User(u['name'], u['phone'], u['email']);
      users.add(user);
    }

    print(users);
    return users;
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: loadJson(),
      builder: (BuildContext context, AsyncSnapshot snapshot) {
        if (!snapshot.hasData) {
          return Container(
            child: Center(
              child: Text("Loading...."),
            ),
          );
        } else {
          return ListView.builder(
              itemCount: snapshot.data.length,
              itemBuilder: (BuildContext context, int index) {
                return ListTile(
                  leading: CircleAvatar(
                    child: Text(snapshot.data[index].name[0]),
                  ),
                  title: Text(snapshot.data.uName),
                  subtitle: Text(snapshot.data[index].phone),
                  trailing: Icon(Icons.phone),
                  onTap: () {
                    Route r = MaterialPageRoute(
                        builder: (context) => details(snapshot.data[index].name,
                            snapshot.data[index].phone));
                    Navigator.push(context, r);
                  },
                );
              });
        }
      },
    );
  }
}

class User {
  final String name;
  final String phone;
  final String email;

  User(this.name, this.phone, this.email);

  String get uName {
    return name;
  }

  String get uPhone {
    return phone;
  }
  String get uEmail {
    return email;
  }
}

这是错误：

I/flutter (29551): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (29551): The following NoSuchMethodError was thrown building:
I/flutter (29551): Class 'List<User>' has no instance getter 'uName'.
I/flutter (29551): Receiver: Instance(length:6) of '_GrowableList'
I/flutter (29551): Tried calling: uName
I/flutter (29551): When the exception was thrown, this was the stack:
I/flutter (29551): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
I/flutter (29551): #1      HomeWidgets.build.<anonymous closure>.<anonymous closure> (package:practising/screens/home.dart:49:45)
I/flutter (29551): #2      SliverChildBuilderDelegate.build (package:flutter/src/widgets/sliver.dart:442:15)
I/flutter (29551): #3      SliverMultiBoxAdaptorElement._build.<anonymous closure> (package:flutter/src/widgets/sliver.dart:1153:67)
I/flutter (29551): #4      _HashMap.putIfAbsent (dart:collection-patch/collection_patch.dart:137:29)
I/flutter (29551): #5      SliverMultiBoxAdaptorElement._build (package:flutter/src/widgets/sliver.dart:1153:26)
I/flutter (29551): #6      SliverMultiBoxAdaptorElement.createChild.<anonymous closure> (package:flutter/src/widgets/sliver.dart:1166:55)
I/flutter (29551): #7      BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2328:19)
I/flutter (29551): #8      SliverMultiBoxAdaptorElement.createChild (package:flutter/src/widgets/sliver.dart:1159:11)
I/flutter (29551): #9      RenderSliverMultiBoxAdaptor._createOrObtainChild.<anonymous closure> (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:354:23)

═══════════════════════════════════════════════ ══════════════════════════════════════════════════ ═══ I / [MALI] Gralloc：[+] r_hnd（0xae4b8fa0），客户端（56），share_fd（60） D / GraphicBuffer（29551）：寄存器，句柄（0xae4b8fa0）（w：540 h：960 s：544 f：0x1 u：0x000b00）

════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
The following NoSuchMethodError was thrown building:
Class 'List<User>' has no instance getter 'uName'.
Receiver: Instance(length:6) of '_GrowableList'
Tried calling: uName

When the exception was thrown, this was the stack: 
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
#1      HomeWidgets.build.<anonymous closure>.<anonymous closure> (package:practising/screens/home.dart:49:45)
#2      SliverChildBuilderDelegate.build (package:flutter/src/widgets/sliver.dart:442:15)
#3      SliverMultiBoxAdaptorElement._build.<anonymous closure> (package:flutter/src/widgets/sliver.dart:1153:67)
#4      _HashMap.putIfAbsent (dart:collection-patch/collection_patch.dart:137:29)
...
════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter (29551): [Instance of 'User', Instance of 'User', Instance of 'User', Instance of 'User', Instance of 'User', Instance of 'User']

════════ (2) Exception caught by widgets library ═══════════════════════════════════════════════════
Class 'List<User>' has no instance getter 'uName'.
Receiver: Instance(length:6) of '_GrowableList'
Tried calling: uName

Answer 1

替换此行；

title: Text(snapshot.data.uName)

使用

title: Text(snapshot.data[index].uName)

Flutter：未来清单问题

1 个答案: