【发布时间】：2019-08-27 22:39:30
【问题描述】：
我使用一些共享首选项来读取和保存列表，但我得到的只是一个错误，如下所示：
Launching lib/main.dart on iPhone 7 in debug mode...
Xcode build done. 4.1s
Tried calling: getString("t")
#0 Object.noSuchMethod (dart:core/runtime/libobject_patch.dart:50:5)
#1 ShareUtils.get
package:todolist2019/ShareUtils.dart:22
<asynchronous suspension>
#2 HomeScreenState.getTaskTitle
package:todolist2019/home.dart:38
#3 _AsyncAwaitCompleter.start (dart:async/runtime/libasync_patch.dart:49:6)
#4 HomeScreenState.getTaskTitle
package:todolist2019/home.dart:35
#5 HomeScreenState.build.<anonymous closure>
package:todolist2019/home.dart:97
#6 SliverChildBuilderDelegate.build
package:flutter/…/widgets/sliver.dart:398
这是我的 home.dart 代码，我的主屏幕
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'dart:async';
import 'package:flutter/services.dart';
import './additem.dart';
import './ShareUtils.dart';
class HomeScreen extends StatefulWidget {
@override
State<StatefulWidget> createState() {
// TODO: implement createState
return HomeScreenState();
}
}
Timer timer;
DateTime now = DateTime.now();
String formattedTime = DateFormat('kk:mm').format(now);
String formattedDate = DateFormat('EEE d MMM').format(now);
class HomeScreenState extends State<HomeScreen> {
void changeTimeAndSetPref() {
setState(() {
DateTime now = DateTime.now();
formattedTime = DateFormat('kk:mm').format(now);
formattedDate = DateFormat('EEE d MMM').format(now);
});
}
Future getTaskTitle(index) async {
shareUtils = new ShareUtils();
shareUtils.Instance();
await shareUtils.get("title"[index]);
}
void initState() {
super.initState();
// Add listeners to this class
timer = Timer.periodic(Duration(seconds: 1), (Timer t) => changeTimeAndSetPref());
}
@override
Widget build(BuildContext context) {
// TODO: implement build
SystemChrome.setEnabledSystemUIOverlays([SystemUiOverlay.bottom]);
return Scaffold(
floatingActionButton: FloatingActionButton.extended(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => addItem()),
);
},
icon: Icon(Icons.add),
label: Text("Add Item"),
),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
body: Column(
children: <Widget>[
Center(
//set the correct sizes
child: Card(
child: Column(
children: <Widget>[
Text(
formattedTime,
style: TextStyle(
fontSize: 50.0,
),
),
Text(
formattedDate,
style: TextStyle(
fontSize: 35.0,
),
),
Text(
"You have impending tasks",
style: TextStyle(
fontSize: 25.0,
),
)
],
),
),
),
Expanded(
child: ListView.builder(
itemBuilder: (context, index) {
var title = getTaskTitle(index).toString();
var detail = taskTitleList[index];
EdgeInsets.all(16.0);
return ListTile(
title: Text(
title,
style: TextStyle(fontSize: 20.0),
),
subtitle: Text(
detail,
style: TextStyle(fontSize: 15.0),
),
onTap: () {
final snackBar = SnackBar(
content: Text('Item Removed'),
duration: Duration(seconds: 1),
);
setState(() {
taskTextList.removeAt(index);
taskTitleList.removeAt(index);
Scaffold.of(context).showSnackBar(snackBar);
});
},
);
},
itemCount: taskTextList.length,
),
)
],
),
);
}
}
这是我的 additem.dart 代码
import 'package:flutter/material.dart';
import './home.dart';
import './ShareUtils.dart';
class addItem extends StatefulWidget {
@override
State<StatefulWidget> createState() {
// TODO: implement createState
return addItemState();
}
}
ShareUtils shareUtils;
var TaskTextField;
var TaskDetailField;
var taskTextList = [];
var taskTitleList = [];
var TaskIsImportant = false;
class addItemState extends State<addItem> {
@override
Widget build(BuildContext context) {
// TODO: implement build
void saveTask (key, value) async {
await shareUtils.set(key, value);
}
return Scaffold(
floatingActionButton: FloatingActionButton.extended(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => HomeScreen()),
);
setState(()async {
if (TaskIsImportant) {
taskTextList.add("❗$TaskTextField");
taskTitleList.add("$TaskDetailField");
saveTask("title", taskTextList);
} else {
taskTextList.add("$TaskTextField");
taskTitleList.add("$TaskDetailField");
saveTask("title", taskTextList);
}
});
},
label: Text("Add Task"),
icon: Icon(Icons.add),
),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
body: Flex(
direction: Axis.vertical,
children: <Widget>[
Flexible(
child: Container(
child: Column(
children: <Widget>[
Card(
child: Column(
children: <Widget>[
Center(
child: Text(
"Welcome!",
style: TextStyle(fontSize: 50.0),
),
),
Center(
child: Text(
"Enter your task below",
style: TextStyle(fontSize: 25.0),
),
),
],
),
),
Container(
child: TextField(
decoration: InputDecoration(
hintText: "Enter title of task to be added",
hintStyle: TextStyle(fontSize: 20.0)),
onChanged: (taskTextField) {
setState(() {
TaskTextField = taskTextField;
print(TaskTextField);
});
},
),
margin: EdgeInsets.all(16.0),
),
Container(
child: TextField(
decoration: InputDecoration(
hintText: "Enter detail of task to be added",
hintStyle: TextStyle(fontSize: 20.0)),
onChanged: (taskDetailField) {
setState(() {
TaskDetailField = taskDetailField;
print(TaskDetailField);
});
},
),
margin: EdgeInsets.all(16.0),
),
CheckboxListTile(
title: Text(
"Important",
style: TextStyle(fontSize: 25.0),
),
activeColor: Colors.blue,
value: TaskIsImportant,
onChanged: (val) {
setState(() {
TaskIsImportant = !TaskIsImportant;
print(TaskIsImportant);
});
},
),
],
),
),
)
],
));
}
}
我希望有人可以帮助我解决这个错误。我在 Flutter 1.2.1 上运行。提前致谢！ PS：我已经实现了 Akio 的代码，但仍然有错误，但较少。我还添加了前 6 行错误消息。
【问题讨论】：
-
您的代码太大而无法阅读...添加一些日志...可能从开始到 5-6 行。
-
好的，我已经添加了错误日志（前 6 行）
-
var title = getTaskTitle(index);此行返回一个 Future，然后您将其用作文本的参数，该文本需要字符串`Text(title, style: TextStyle(fontSize:25.0))` 看看 future builder
-
好的会试试
-
对了，请问futurebuilder是如何使用的？我是这种语言的新手，以前从未使用过 futurebuilder。