flutter - Flutter - 未处理的异常：NoSuchMethodError：在 null 上调用了方法“验证”
问题描述
我有以下NoSuchMethodError异常：
W/IInputConnectionWrapper(15165): getTextAfterCursor on inactive InputConnection
W/IInputConnectionWrapper(15165): getTextBeforeCursor on inactive InputConnection
W/IInputConnectionWrapper(15165): getSelectedText on inactive InputConnection
W/IInputConnectionWrapper(15165): getTextAfterCursor on inactive InputConnection
E/flutter (15165): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: NoSuchMethodError: The method 'validate' was called on null.
E/flutter (15165): Receiver: null
E/flutter (15165): Tried calling: validate()
E/flutter (15165): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)
E/flutter (15165): #1 _SignUpState.build.<anonymous closure> (package:meds_at_home/pages/signup.dart:246:55)
E/flutter (15165): #2 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:706:14)
E/flutter (15165): #3 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:789:36)
E/flutter (15165): #4 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
E/flutter (15165): #5 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:486:11)
E/flutter (15165): #6 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:264:5)
E/flutter (15165): #7 BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:236:7)
E/flutter (15165): #8 GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
E/flutter (15165): #9 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:222:20)
E/flutter (15165): #10 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:198:22)
E/flutter (15165): #11 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:156:7)
E/flutter (15165): #12 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:102:7)
E/flutter (15165): #13 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:86:7)
E/flutter (15165): #14 _rootRunUnary (dart:async/zone.dart:1138:13)
E/flutter (15165): #15 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter (15165): #16 _CustomZone.runUnaryGuarded (dart:async/zone.dart:933:7)
E/flutter (15165): #17 _invoke1 (dart:ui/hooks.dart:273:10)
E/flutter (15165): #18 _dispatchPointerDataPacket (dart:ui/hooks.dart:182:5)
这是我的颤振医生：
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, v1.12.13+hotfix.8, on Microsoft Windows [Version 10.0.18363.657], locale en-US)
[√] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
[√] Android Studio (version 3.6)
[!] VS Code (version 1.42.1)
X Flutter extension not installed; install from
https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter
[√] Connected device (1 available)
! Doctor found issues in 1 category.
这是我的注册码：
import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_database/firebase_database.dart';
import 'package:meds_at_home/pages/home.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import '../db/users.dart';
class SignUp extends StatefulWidget {
@override
_SignUpState createState() => _SignUpState();
}
class _SignUpState extends State<SignUp> {
final FirebaseAuth firebaseAuth = FirebaseAuth.instance;
final _formKey = GlobalKey<FormFieldState>();
UserServices _userServices = UserServices();
TextEditingController _email = TextEditingController();
TextEditingController _password = TextEditingController();
TextEditingController _name = TextEditingController();
TextEditingController _confirmPassword = TextEditingController();
String gender;
String groupvalue = "Male";
bool hidePass = true;
bool hidePass1 = true;
bool loading = false;
@override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(children: <Widget>[
Image.asset(
'images/back1.webp',
fit: BoxFit.fill,
width: double.infinity,
height: double.infinity,
),
// Container(
// alignment: Alignment.topRight,
// child: Image.asset('images/logo.png'),
// width: 240.0,
// height: 200.0,
// ),
Container(
color: Colors.black12.withOpacity(0.4),
width: double.infinity,
height: double.infinity,
),
Center(
child: Padding(
padding: const EdgeInsets.only(top: 150.0),
child: Center(
child: Form(
key: _formKey,
child: ListView(
children: <Widget>[
Padding(
padding:
const EdgeInsets.fromLTRB(14.0, 4.0, 14.0, 4.0),
child: Material(
borderRadius: BorderRadius.circular(10.0),
color: Colors.white.withOpacity(0.8),
elevation: 0.0,
child: Padding(
padding: const EdgeInsets.only(left: 12.0),
child: TextFormField(
controller: _name,
decoration: InputDecoration(
border: InputBorder.none,
hintText: "Full Name",
icon: Icon(Icons.person),
),
validator: (value) {
if (value.isEmpty) {
return "The name field cannot be empty";
}
return null;
},
),
),
),
),
Padding(
padding:
const EdgeInsets.fromLTRB(14.0, 4.0, 14.0, 4.0),
child: new Container(
color: Colors.white.withOpacity(0.2),
child: Row(
children: <Widget>[
Expanded(
child: ListTile(
title: Text(
"Male",
textAlign: TextAlign.end,
style: TextStyle(color: Colors.white),
),
trailing: Radio(
value: "Male",
groupValue: groupvalue,
onChanged: (e) => valueChanged(e)),
)),
Expanded(
child: ListTile(
title: Text(
"Female",
textAlign: TextAlign.end,
style: TextStyle(color: Colors.white),
),
trailing: Radio(
value: "Female",
groupValue: groupvalue,
onChanged: (e) => valueChanged(e)),
)),
],
),
),
),
Padding(
padding:
const EdgeInsets.fromLTRB(14.0, 4.0, 14.0, 4.0),
child: Material(
borderRadius: BorderRadius.circular(10.0),
color: Colors.white.withOpacity(0.8),
elevation: 0.0,
child: Padding(
padding: const EdgeInsets.only(left: 12.0),
child: TextFormField(
controller: _email,
decoration: InputDecoration(
border: InputBorder.none,
hintText: "Email",
icon: Icon(Icons.email),
),
// ignore: missing_return
validator: (value) {
if (value.isEmpty) {
Pattern pattern =
r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
RegExp regex = new RegExp(pattern);
if (!regex.hasMatch(value))
return 'Please make sure your email address is valid';
else
return null;
}
},
),
),
),
),
Padding(
padding:
const EdgeInsets.fromLTRB(14.0, 4.0, 14.0, 4.0),
child: Material(
borderRadius: BorderRadius.circular(10.0),
color: Colors.white.withOpacity(0.8),
elevation: 0.0,
child: Padding(
padding: const EdgeInsets.only(left: 12.0),
child: ListTile(
title: TextFormField(
controller: _password,
obscureText: hidePass,
decoration: InputDecoration(
border: InputBorder.none,
hintText: "Password",
icon: Icon(Icons.lock_outline),
),
validator: (value) {
if (value.isEmpty) {
return "The password field cannot be empty";
} else if (value.length < 6) {
return "The password should have at least 6 characters ";
}
return null;
},
),
trailing: IconButton(
icon: Icon(Icons.remove_red_eye),
onPressed: () {
setState(() {
if (hidePass == false) {
hidePass = true;
} else {
hidePass = false;
}
});
}),
),
),
),
),
Padding(
padding:
const EdgeInsets.fromLTRB(14.0, 4.0, 14.0, 4.0),
child: Material(
borderRadius: BorderRadius.circular(10.0),
color: Colors.white.withOpacity(0.8),
elevation: 0.0,
child: Padding(
padding: const EdgeInsets.only(left: 12.0),
child: ListTile(
title: TextFormField(
controller: _confirmPassword,
obscureText: hidePass1,
decoration: InputDecoration(
border: InputBorder.none,
hintText: "Confirm Password",
icon: Icon(Icons.lock_outline),
),
validator: (value) {
if (value.isEmpty) {
return "The password field cannot be empty";
} else if (value.length < 6) {
return "The password should have at least 6 characters";
} else if (_password.text != value) {
return "Password Don't match";
}
return null;
},
),
trailing: IconButton(
icon: Icon(Icons.remove_red_eye),
onPressed: () {
setState(() {
if (hidePass1 == false) {
hidePass1 = true;
} else {
hidePass1 = false;
}
});
}),
),
),
),
),
Padding(
padding:
const EdgeInsets.fromLTRB(14.0, 4.0, 14.0, 4.0),
child: Material(
borderRadius: BorderRadius.circular(20.0),
color: Colors.blueAccent,
elevation: 0.0,
child: MaterialButton(
onPressed: () async {
_formKey.currentState.validate();
},
// async{
// if(_formKey.currentState.validate()){
// if(!await user.signIn(_email.text, _password.text))
// _key.currentState.showSnackBar(SnackBar(content: Text("Sign in failed")));
// }
// },
minWidth: MediaQuery
.of(context)
.size
.width,
child: Text(
"Register",
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.white,
fontWeight: FontWeight.bold,
fontSize: 20.0),
),
)),
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
Padding(
padding: const EdgeInsets.all(6.0),
child: InkWell(
onTap: () {
Navigator.pop(context);
},
child: Text(
"I already have an account",
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.black,
fontWeight: FontWeight.bold,
fontSize: 16),
))),
],
),
],
)),
),
),
),
Visibility(
visible: loading ?? true,
child: Center(
child: Container(
alignment: Alignment.center,
color: Colors.white.withOpacity(0.2),
child: CircularProgressIndicator(
valueColor: AlwaysStoppedAnimation<Color>(Colors.blueAccent),
),
),
)),
]),
//
);
}
valueChanged(e) {
setState(() {
if (e == "Male") {
groupvalue = e;
gender = e;
} else if (e == "Female") {
groupvalue = e;
gender = e;
}
});
}
Future validate() async {
FormFieldState formState = _formKey.currentState;
if (_formKey.currentState.validate()) {
formState.reset();
FirebaseUser user = await firebaseAuth.currentUser();
if (user == null) {
firebaseAuth
.createUserWithEmailAndPassword(
email: _email.text, password: _password.text)
.then((authResult) =>
{
_userServices.createUser(
user.uid,
{
"username": user.displayName,
"email": user.email,
"gender": gender,
}
)
}).catchError((err) => {print(err.toString())});
Navigator.pushReplacement(
context, MaterialPageRoute(builder: (context) => HomePage()));
}
}
}
}
这是我的数据库/用户页面
import 'package:firebase_database/firebase_database.dart';
class UserServices {
FirebaseDatabase _database = FirebaseDatabase.instance;
String ref = "users";
createUser(String uid,Map value) {
_database
.reference()
.child("$ref/$uid")
.set(value)
.catchError((e) => {print(e.toString())});
}
}
我尝试了很多事情来解决，但没有奏效。
解决方案
也许您应该检查是否所有表单变量都分配了值，其中一个是 null 这就是您收到错误的原因
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