如何解决飞镖颤振scaffoldKey问题？
如何解决飞镖颤振scaffoldKey问题？
提问于 2022-10-25 15:53:00
我将描述我的编码问题。
我已经创建了登录/注册.dart文件(页面)，但是在调试时我得到了这个错误.
The method 'showSnackBar' isn`t defined for the type 'ScaffoldState'.
这条错误信息在.dart代码中随处可见，我有这条编码行.
`
scaffoldKey.currentState.showSnackBar(snackbar);`
下面是我的"login_page.dart“文件的完整代码.
`
class LoginPage extends StatefulWidget {
@override
_LoginPageState createState() => _LoginPageState();
}
class _LoginPageState extends State<LoginPage> {
final GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey<ScaffoldState>();
void showSnackBar(String title) {
final snackbar = SnackBar(
content: Text(
title,
textAlign: TextAlign.center,
style: TextStyle(fontSize: 15),
),
);
scaffoldKey.currentState.showSnackBar(snackbar);
}
var emailIdController = TextEditingController();
var passwordController = TextEditingController();
Widget _buildLogin() {
return Padding(
padding: EdgeInsets.symmetric(horizontal: 30),
child: Column(
children: [
InputTextField(
controller: emailIdController,
label: 'Email-Id',
icon: Icon(Icons.email_outlined),
),
InputTextField(
controller: passwordController,
label: 'Password',
icon: Icon(Icons.lock),
),
SizedBox(
height: 50,
),
GestureDetector(
onTap: () async {
// network connectivity
var connectivityResult = await Connectivity().checkConnectivity();
if (connectivityResult != ConnectivityResult.mobile &&
connectivityResult != ConnectivityResult.wifi) {
showSnackBar('No Internet connectivity');
return;
}
if (!emailIdController.text.contains('@')) {
showSnackBar('Please provide a valid email address');
}
if (passwordController.text.length < 6) {
showSnackBar('Please provide a password of length more than 6');
}
BuildContext dialogContext;
showDialog(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
dialogContext = context;
return ProgressDialog(
status: 'Logging you in...',
);
},
);
context
.read<AuthenticationService>()
.signIn(
email: emailIdController.text.trim(),
password: passwordController.text.trim(),
)
.then((value) => Navigator.push(
context,
MaterialPageRoute(builder: (context) {
return HomePage();
}),
));
Navigator.pop(dialogContext);
},
child: CustomButton(
text: 'Login',
),
),
Text("\nDon't have any account?"),
GestureDetector(
onTap: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) {
return SignUpPage();
}),
);
},
child: Text(
'SignUp here',
style: TextStyle(fontWeight: FontWeight.bold, fontSize: 12),
),
),
SizedBox(
height: 20,
),
],
),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
key: scaffoldKey,
body: SingleChildScrollView(
physics: BouncingScrollPhysics(),
child: Padding(
padding: EdgeInsets.only(top: 130),
child: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
Text(
'hopOn',
style: TextStyle(
fontSize: 60,
letterSpacing: 2,
fontWeight: FontWeight.bold,
fontFamily: 'MuseoModerno',
// color: Colors.white,
),
),
SizedBox(height: 80),
Padding(
padding: EdgeInsets.symmetric(horizontal: 30),
child: Column(
children: [
InputTextField(
controller: emailIdController,
label: 'Email-Id',
obscure: false,
icon: Icon(Icons.email_outlined),
),
InputTextField(
controller: passwordController,
label: 'Password',
obscure: true,
icon: Icon(Icons.lock),
),
SizedBox(
height: 30,
),
GestureDetector(
onTap: () async {
// network connectivity
var connectivityResult =
await Connectivity().checkConnectivity();
if (connectivityResult != ConnectivityResult.mobile &&
connectivityResult != ConnectivityResult.wifi) {
showSnackBar('No Internet connectivity');
return;
}
if (!emailIdController.text.contains('@')) {
showSnackBar(
'Please provide a valid email address');
}
if (passwordController.text.length < 6) {
showSnackBar(
'Please provide a password of length more than 6');
}
BuildContext dialogContext;
showDialog(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
dialogContext = context;
return ProgressDialog(
status: 'Logging you in...',
);
},
);
context
.read<AuthenticationService>()
.signIn(
email: emailIdController.text.trim(),
password: passwordController.text.trim(),
)
.then((value) => Navigator.push(
context,
MaterialPageRoute(builder: (context) {
return HomePage();
}),
));
Navigator.pop(dialogContext);
},
child: CustomButton(
text: 'Login',
),
),
SizedBox(
height: 20,
),
GestureDetector(
onTap: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) {
return SignUpPage();
}),
);
},
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
"Don't have any account?\t",
style: TextStyle(fontSize: 10),
),
Text(
'SignUp here',
style: TextStyle(
fontWeight: FontWeight.bold, fontSize: 12),
),
],
),
),
SizedBox(
height: 20,
),
],
),
),
],
),
),
),
),
);
}
}`
整个代码的问题出现在这个类中..。
`
void showSnackBar(String title) {
final snackbar = SnackBar(
content: Text(
title,
textAlign: TextAlign.center,
style: TextStyle(fontSize: 15),
),
);
scaffoldKey.currentState.showSnackBar(snackbar); // <=== here is problem, this line have error message --> The method 'showSnackBar' isn`t defined for the type 'ScaffoldState'.
}`
任何帮助都是非常感谢的。谢谢!
我想修复"snackBar“错误问题。我试了几个小时自己解决它，但没有成功。
回答 2
Stack Overflow用户
发布于 2022-10-25 16:07:00
Flutter使用下面的方法按照flutter.dev显示snackbar
ScaffoldMessenger.of(context).showSnackBar(snackBar);Stack Overflow用户
发布于 2022-10-25 17:04:20
我发现了另一个名为"Rohan“的用户给我的解决方案。
我更改了有问题的代码行..。
scaffoldKey.currentState.showSnackBar(snackbar);对于第一个解决方案(仍然没有工作，出现错误“未定义的名称：‘snackbar’”).
ScaffoldMessenger.of(context).showSnackBar(snackBar);没有起作用，但后来我从以前的样品溶液中找到了一个解决方案。这是我的问题的通用解决方案.
ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: snackbar));如果您发现"showSnackBar“存在相同或类似的问题，此解决方案将对您有所帮助。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/74196873
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