如何消除此错误：不正确使用ParentDataWidget
我没有使用Expanded窗口小部件，但我不知道为什么一直收到此错误。 窗口小部件库未捕获的异常，在四个地方错误地使用了ParentDataWidget ，我无法确切知道错误的出处。尽管它不会阻止我使用该应用程序，但我认为它应该已修复。请任何人能帮助我吗？ 这是我的代码如下：
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:erg_app/Anchors.dart';
import 'package:erg_app/api/api.dart';
import 'package:shared_preferences/shared_preferences.dart';
class LogIn extends StatefulWidget {
@override
_LogInState createState() => _LogInState();
}
class _LogInState extends State<LogIn> {
bool _isLoading = false;
TextEditingController mailController = TextEditingController();
TextEditingController passwordController = TextEditingController();
final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
ScaffoldState scaffoldState;
_showMsg() {
final snackBar = SnackBar(
content: Text(
'Invalid Username or Password',
style: (TextStyle(fontSize: 18)),
),
backgroundColor: Colors.amber[900],
);
_scaffoldKey.currentState.showSnackBar(snackBar);
}
@override
Widget build(BuildContext context) {
return GestureDetector(
onTap: () {
FocusScopeNode currentFocus = FocusScope.of(context);
if (!currentFocus.hasPrimaryFocus) {
currentFocus.unfocus();
}
},
child: Scaffold(
key: _scaffoldKey,
body: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topLeft,
end: Alignment.bottomRight,
stops: [0.0, 0.4, 0.9],
colors: [
Color(0XFF4CAF50),
Color(0xFF388E3C),
Color(0xFF075009),
],
),
),
child: ListView(
children: <Widget>[
/////////// background///////////
SizedBox(height: 30),
new Container(
width: 100.00,
height: 100.00,
decoration: new BoxDecoration(
image: new DecorationImage(
image: AssetImage('assets/images/icon.png'),
fit: BoxFit.contain,
),
)),
Column(
children: <Widget>[
Positioned(
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Positioned(
left: 30,
top: 100,
child: Container(
margin: EdgeInsets.only(top: 50),
child: Center(
child: Text(
"Welcome",
style: TextStyle(
color: Colors.white,
fontSize: 23,
fontWeight: FontWeight.bold),
),
),
),
),
SizedBox(height: 30),
Card(
elevation: 4.0,
color: Colors.white,
margin: EdgeInsets.only(left: 20, right: 20),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(15)),
child: Padding(
padding: const EdgeInsets.all(10.0),
// child: form(key: _formKey),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
///////////// Email//////////////
TextField(
style: TextStyle(color: Color(0xFF000000)),
controller: mailController,
cursorColor: Color(0xFF9b9b9b),
keyboardType: TextInputType.text,
decoration: InputDecoration(
prefixIcon: Icon(
Icons.account_circle,
color: Colors.grey,
),
hintText: "Username",
hintStyle: TextStyle(
color: Color(0xFF9b9b9b),
fontSize: 15,
fontWeight: FontWeight.normal),
focusedBorder: OutlineInputBorder(
borderSide:
BorderSide(color: Colors.green)),
),
),
/////////////// password////////////////////
TextField(
style: TextStyle(color: Color(0xFF000000)),
cursorColor: Color(0xFF9b9b9b),
controller: passwordController,
keyboardType: TextInputType.number,
obscureText: true,
decoration: InputDecoration(
prefixIcon: Icon(
Icons.vpn_key,
color: Colors.grey,
),
focusedBorder: OutlineInputBorder(
borderSide:
BorderSide(color: Colors.green)),
hintText: "Password",
hintStyle: TextStyle(
color: Color(0xFF9b9b9b),
fontSize: 15,
fontWeight: FontWeight.normal),
),
),
///////////// LogIn Botton///////////////////
Padding(
padding: const EdgeInsets.all(10.0),
child: FlatButton(
child: Padding(
padding: EdgeInsets.only(
top: 8,
bottom: 8,
left: 10,
right: 10),
child: Text(
_isLoading ? 'Loging...' : 'Login',
textDirection: TextDirection.ltr,
style: TextStyle(
color: Colors.white,
fontSize: 15.0,
decoration: TextDecoration.none,
fontWeight: FontWeight.normal,
),
),
),
color: Colors.green,
disabledColor: Colors.grey,
shape: new RoundedRectangleBorder(
borderRadius:
new BorderRadius.circular(20.0)),
onPressed: _isLoading ? null : _login,
),
),
],
),
),
),
//////////// new account///////////////
Padding(
padding: const EdgeInsets.only(top: 20),
child: InkWell(
onTap: () {
Navigator.push(
context,
new MaterialPageRoute(
builder: (context) => LogIn()));
},
child: Text(
'Forgot Your Password?',
textDirection: TextDirection.ltr,
style: TextStyle(
color: Colors.white,
fontSize: 15.0,
decoration: TextDecoration.none,
fontWeight: FontWeight.normal,
),
),
),
),
],
),
),
),
],
)
],
),
),
));
// Gesture ends here
}
}
这是错误消息的图片：
1 个答案:
答案 0 :(得分：2)
您在代码的不同部分的Positioned小部件中有一个Column小部件。
Positioned小部件必须是Stack的后代，并且路径必须是 封闭堆栈中的定位小部件必须仅包含 StatelessWidgets或StatefulWidgets
我从Flutter docs粘贴了上面的内容，并说Positioned必须是Stack的后代，也就是说，除了Stack之外，您不能在其他小部件中拥有位置小部件。
您应该从代码中删除Positioned小部件。或用Stack小部件包装它们
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:erg_app/Anchors.dart';
import 'package:erg_app/api/api.dart';
import 'package:shared_preferences/shared_preferences.dart';
class LogIn extends StatefulWidget {
@override
_LogInState createState() => _LogInState();
}
class _LogInState extends State<LogIn> {
bool _isLoading = false;
TextEditingController mailController = TextEditingController();
TextEditingController passwordController = TextEditingController();
final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
ScaffoldState scaffoldState;
_showMsg() {
final snackBar = SnackBar(
content: Text(
'Invalid Username or Password',
style: (TextStyle(fontSize: 18)),
),
backgroundColor: Colors.amber[900],
);
_scaffoldKey.currentState.showSnackBar(snackBar);
}
@override
Widget build(BuildContext context) {
return GestureDetector(
onTap: () {
FocusScopeNode currentFocus = FocusScope.of(context);
if (!currentFocus.hasPrimaryFocus) {
currentFocus.unfocus();
}
},
child: Scaffold(
key: _scaffoldKey,
body: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topLeft,
end: Alignment.bottomRight,
stops: [0.0, 0.4, 0.9],
colors: [
Color(0XFF4CAF50),
Color(0xFF388E3C),
Color(0xFF075009),
],
),
),
child: ListView(
children: <Widget>[
/////////// background///////////
SizedBox(height: 30),
new Container(
width: 100.00,
height: 100.00,
decoration: new BoxDecoration(
image: new DecorationImage(
image: AssetImage('assets/images/icon.png'),
fit: BoxFit.contain,
),
)),
Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Container(
margin: EdgeInsets.only(top: 50),
child: Center(
child: Text(
"Welcome",
style: TextStyle(
color: Colors.white,
fontSize: 23,
fontWeight: FontWeight.bold),
),
),
),
SizedBox(height: 30),
Card(
elevation: 4.0,
color: Colors.white,
margin: EdgeInsets.only(left: 20, right: 20),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(15)),
child: Padding(
padding: const EdgeInsets.all(10.0),
// child: form(key: _formKey),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
///////////// Email//////////////
TextField(
style: TextStyle(color: Color(0xFF000000)),
controller: mailController,
cursorColor: Color(0xFF9b9b9b),
keyboardType: TextInputType.text,
decoration: InputDecoration(
prefixIcon: Icon(
Icons.account_circle,
color: Colors.grey,
),
hintText: "Username",
hintStyle: TextStyle(
color: Color(0xFF9b9b9b),
fontSize: 15,
fontWeight: FontWeight.normal),
focusedBorder: OutlineInputBorder(
borderSide:
BorderSide(color: Colors.green)),
),
),
/////////////// password////////////////////
TextField(
style: TextStyle(color: Color(0xFF000000)),
cursorColor: Color(0xFF9b9b9b),
controller: passwordController,
keyboardType: TextInputType.number,
obscureText: true,
decoration: InputDecoration(
prefixIcon: Icon(
Icons.vpn_key,
color: Colors.grey,
),
focusedBorder: OutlineInputBorder(
borderSide:
BorderSide(color: Colors.green)),
hintText: "Password",
hintStyle: TextStyle(
color: Color(0xFF9b9b9b),
fontSize: 15,
fontWeight: FontWeight.normal),
),
),
///////////// LogIn Botton///////////////////
Padding(
padding: const EdgeInsets.all(10.0),
child: FlatButton(
child: Padding(
padding: EdgeInsets.only(
top: 8,
bottom: 8,
left: 10,
right: 10),
child: Text(
_isLoading ? 'Loging...' : 'Login',
textDirection: TextDirection.ltr,
style: TextStyle(
color: Colors.white,
fontSize: 15.0,
decoration: TextDecoration.none,
fontWeight: FontWeight.normal,
),
),
),
color: Colors.green,
disabledColor: Colors.grey,
shape: new RoundedRectangleBorder(
borderRadius:
new BorderRadius.circular(20.0)),
onPressed: _isLoading ? null : _login,
),
),
],
),
),
),
//////////// new account///////////////
Padding(
padding: const EdgeInsets.only(top: 20),
child: InkWell(
onTap: () {
Navigator.push(
context,
new MaterialPageRoute(
builder: (context) => LogIn()));
},
child: Text(
'Forgot Your Password?',
textDirection: TextDirection.ltr,
style: TextStyle(
color: Colors.white,
fontSize: 15.0,
decoration: TextDecoration.none,
fontWeight: FontWeight.normal,
),
),
),
),
],
),
),
],
)
],
),
),
));
// Gesture ends here
}
}
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