我正在制作身份驗證登錄表單并希望連接submitAuthForm Function到AuthForm. 這就是為什么我在AuthForm. 我是初學者。請幫我解決這個問題（引數型別void Function(String, String, String, bool)不能分配給引數型別void Function(String, String, String, bool)
謝謝。
class AuthScreen extends StatefulWidget {
@override
_AuthScreenState createState() => _AuthScreenState();
}
class _AuthScreenState extends State<AuthScreen> {
void _submitAuthForm(
String email,
String password,
String username,
bool isLogin) {
}
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Theme.of(context).primaryColor,
body: Authform(_submitAuthForm,)/*( The argument type 'void Function(String, String, String, bool)' can't be assigned to the parameter type 'Void Function(String, String, String, bool)'.*/)
);
}
}
class Authform extends StatefulWidget {
Authform(this.submitFN);
final Void Function(
String email, String password, String username, bool isLogin) submitFN;
@override
_AuthformState createState() => _AuthformState();
}
class _AuthformState extends State<Authform> {
final _formKey = GlobalKey<FormState>();
var _isLogin = true;
var _userEmail;
var _userName;
var _userPassword;
void _trySubmit() {
final isValid = _formKey.currentState!.validate();
FocusScope.of(context).unfocus();
if (isValid) {
_formKey.currentState!.save();
widget.submitFN(_userEmail,_userPassword,_userName,_isLogin);
}
}
@override
Widget build(BuildContext context) {
return Center(
child: Card(
margin: EdgeInsets.all(20),
child: SingleChildScrollView(
child: Padding(
padding: EdgeInsets.all(16),
child: Form(
key: _formKey,
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
TextFormField(
key: ValueKey('email'),
validator: (value) {
if (value!.isEmpty || !value.contains('@')) {
return 'please enter valid email address';
}
return null;
},
keyboardType: TextInputType.emailAddress,
decoration: InputDecoration(
icon: Icon(
Icons.mail,
color: Colors.orange,
),
labelText: 'Email Addess'),
onSaved: (value) {
_userEmail = value;
},
),
if (!_isLogin)
TextFormField(
key: ValueKey('username'),
validator: (value) {
if (value!.isEmpty || value.length < 4) {
return 'Username is short enter atleast 4 characters ';
}
},
decoration: InputDecoration(
icon: Icon(
Icons.person,
color: Colors.orange,
),
labelText: 'Username'),
onSaved: (value) {
_userName = value;
},
),
TextFormField(
key: ValueKey('password'),
validator: (value) {
if (value!.isEmpty || value.length < 7) {
return 'Password must be atleast 7 characters long';
}
return null;
},
decoration: InputDecoration(
icon: Icon(
Icons.lock,
color: Colors.orange,
),
labelText: 'password',
),
obscureText: true,
onSaved: (value) {
_userPassword = value;
},
),
SizedBox(
height: 12,
),
ElevatedButton(
onPressed: _trySubmit,
child: Text(_isLogin ? 'Login' : 'Signup'),
style: ElevatedButton.styleFrom(onPrimary: Colors.white),
),
TextButton(
onPressed: () {
setState(() {
_isLogin = !_isLogin;
});
},
child: Text(_isLogin
? 'Create new account'
: 'I already have a acoount'))
],
)),
)),
),
);
}
}
uj5u.com熱心網友回復：
宣告函式或變數時，您必須遵循正確的宣告method以避免出現unusual問題。您已宣告您的functionusing Voidthe Vis 在capital case其中，但它必須在small caselike中void。Juts 將其更改為：
final Void Function(
到
final void Function(
uj5u.com熱心網友回復：
import 'package:flutter/material.dart';
void main(List<String> args) {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
theme: ThemeData(),
home: AuthScreen(),
);
}
}
class AuthScreen extends StatefulWidget {
@override
_AuthScreenState createState() => _AuthScreenState();
}
class _AuthScreenState extends State<AuthScreen> {
void _submitAuthForm(
String email, String password, String username, bool isLogin) {}
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Theme.of(context).primaryColor,
body: Authform(
_submitAuthForm,
));
}
}
class Authform extends StatefulWidget {
Authform(this.submitFN);
final void Function(
String email, String password, String username, bool isLogin) submitFN;
@override
_AuthformState createState() => _AuthformState();
}
class _AuthformState extends State<Authform> {
final _formKey = GlobalKey<FormState>();
var _isLogin = true;
var _userEmail;
var _userName;
var _userPassword;
void _trySubmit() {
final isValid = _formKey.currentState!.validate();
FocusScope.of(context).unfocus();
if (isValid) {
_formKey.currentState!.save();
widget.submitFN(_userEmail, _userPassword, _userName, _isLogin);
}
}
@override
Widget build(BuildContext context) {
return Center(
child: Card(
margin: EdgeInsets.all(20),
child: SingleChildScrollView(
child: Padding(
padding: EdgeInsets.all(16),
child: Form(
key: _formKey,
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
TextFormField(
key: ValueKey('email'),
validator: (value) {
if (value!.isEmpty || !value.contains('@')) {
return 'please enter valid email address';
}
return null;
},
keyboardType: TextInputType.emailAddress,
decoration: InputDecoration(
icon: Icon(
Icons.mail,
color: Colors.orange,
),
labelText: 'Email Addess'),
onSaved: (value) {
_userEmail = value;
},
),
if (!_isLogin)
TextFormField(
key: ValueKey('username'),
validator: (value) {
if (value!.isEmpty || value.length < 4) {
return 'Username is short enter atleast 4 characters ';
}
},
decoration: InputDecoration(
icon: Icon(
Icons.person,
color: Colors.orange,
),
labelText: 'Username'),
onSaved: (value) {
_userName `enter code here`= value;
},
),
TextFormField(
key: ValueKey('password'),
validator: (value) {
if (value!.isEmpty || value.length < 7) {
return 'Password must be atleast 7 characters long';
}
return null;
},
decoration: InputDecoration(
icon: Icon(
Icons.lock,
color: Colors.orange,
),
labelText: 'password',
),
obscureText: true,
onSaved: (value) {
_userPassword = value;
},
),
SizedBox(
height: 12,
),
ElevatedButton(
onPressed: _trySubmit,
child: Text(_isLogin ? 'Login' : 'Signup'),
style: ElevatedButton.styleFrom(onPrimary: Colors.white),
),
TextButton(
onPressed: () {
setState(() {
_isLogin = !_isLogin;
});
},
child: Text(_isLogin
? 'Create new account'
: 'I already have a acoount'))
],
)),
)),
),
);
}
}
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