Flutter 颤振中获取错误：-在null上调用了getter

我正在尝试获取用户选择的maxDistance并继续获取此错误。这是从获取数据到显示数据的完整代码。在云Firestore中，数据也被保存，但我不知道为什么我不能在这里显示这些数据。请帮帮我。谢谢。我得到了这个错误：-

 The getter 'maxDistance' was called on null.
 Receiver: null
 Tried calling: maxDistance

这是我将其命名为的屏幕：-

   class More extends StatefulWidget{
  final CreateAccountData currentUser;
  More({this.currentUser,}) ;

   @override
 _MoreState createState() => new _MoreState();
}

class _MoreState extends State<More>
 with SingleTickerProviderStateMixin{
Map<String, dynamic> changeValues = {};

 final auth = FirebaseAuth.instance;
 int distance;
 String currentuser;
 int freeR;
  int paidR;

  @override
 void initState() {
super.initState();
freeR =  500;
paidR =  500;
setState(() {
  if (widget.currentUser.maxDistance > freeR) {
    widget.currentUser.maxDistance = freeR.round();
    changeValues.addAll({'maximum_distance': freeR.round()});
  } else if (
      widget.currentUser.maxDistance >= paidR) {
    widget.currentUser.maxDistance = paidR.round();
    changeValues.addAll({'maximum_distance': paidR.round()});
  }
    distance = widget.currentUser.maxDistance.round();
    });

  }
  @override
 void dispose() {
  super.dispose();
  if (changeValues.length > 0) {
  updateData();
  }
}

 Future updateData() async {
  FirebaseFirestore.instance
    .collection("users")
    .doc(widget.currentUser.uid)
    .set(changeValues,SetOptions( merge: true));

 }

这是我获取数据的模型类：-

      class CreateAccountData {

  final String name, email,DOB,age,uid,username, countryCode ,
           address,phone, password,profilepic,showGender,gender;
 final Map coordinates,editInfo,ageRange;
 final List hobbies ;
int maxDistance;
 var distanceBW;

  CreateAccountData({this.name,this.email,this.DOB,this.age,
this.username,this.uid,this.countryCode,this.address,
this.phone, this.password,this.profilepic,this.coordinates,
this.hobbies,this.gender,this.showGender,this.ageRange,this.maxDistance,
this.editInfo,this.distanceBW});


     factory CreateAccountData.fromJson(Map<String, dynamic> json)    {
  return CreateAccountData(
    name: json['name'],
    email: json['email'],
    age:json['age'],
    DOB:json['DOB'],
    gender: json['gender'],
    hobbies: json['hobbies']['list'],
    address: json['location']['address'],
    coordinates: json['location'],
    username:json['username'],
    uid:json['uid'],
     editInfo:json['editInfo'],
    maxDistance:json['maximum_distance'],
    showGender:json['showGender'],
     phone: json['phone'],
    profilepic : json['profilepic']
);
  }

 factory CreateAccountData.fromDocument(DocumentSnapshot doc){
 return CreateAccountData(
    uid: doc['uid'],
    phone: doc['phone'],
    name: doc['name'],
    editInfo: doc['editInfo'],
    ageRange: doc['age_range'],
    showGender: doc['showGender'],
    maxDistance: doc['maximum_distance'],
    age:doc['age'],
    address: doc['location']['address'],
    coordinates: doc['location'],
  
);
}

 Map<String, dynamic> toMap() {
  return {
  'name':name,
  'email': email,
  'age': age,
  'username':username,
  'DOB':DOB,
  'gender':gender,
  'uid':uid,
  'showGender':showGender,
  'address':address,
  'editInfo':editInfo,
  'hobbies':hobbies,
  'location':coordinates,
  'maximum_distance':maxDistance,
  'phone' : phone,
  'profilepic':profilepic,
};
 }

 }

---

请用调试点检查此行

if (widget.currentUser.maxDistance > freeR) {

我认为currentUser在这里是空的，如果是，这可能会解决您的问题

将此中的第二行更改为

  class More extends StatefulWidget{
      final CreateAccountData currentUser;
      More({this.currentUser,}) ;

对此

CreateAccountData currentUser = CreateAccountData();

---

如果它没有解决您的问题，请确保您正在将currentUser发送到此小部件调试currentUser。我认为您没有将currentUser传递到此页面

widget？.currentUser？.maxDistance！=空

像这样检查

setState(() {
if(widget?.currentUser?.maxDistance != null){
  if (widget.currentUser.maxDistance > freeR) {
    widget.currentUser.maxDistance = freeR.round();
    changeValues.addAll({'maximum_distance': freeR.round()});
  } else if (
      widget.currentUser.maxDistance >= paidR) {
    widget.currentUser.maxDistance = paidR.round();
    changeValues.addAll({'maximum_distance': paidR.round()});
  }
    distance = widget.currentUser.maxDistance.round();
 } else {
    print('currentUser is null ${widget?.currentUser?.maxDistance}')
 }
});

---

是的，我认为currentUser不会访问这个小部件。我该怎么做？我需要在哪里做什么更改？你是否按照我说的检查了？因为最终CreateAccountData currentUser；这条线会制造很多问题。。。但是如果你想确保返回到你正在调用的小部件More widget。。。看看你有没有发什么东西？如果是，请使用调试点检查它，以确保它不是空的或Null如果我将名称“CreateAccountData”更改为“User”，则会出现另一个错误：-没有为类型“User”定义getter“maxDistance”。是的，我已尝试此操作：-CreateAccountData currentUser=CreateAccountData（）；它不起作用。好的，那么请检查您是否正在向此小部件发送任何内容。您可以发布导航到

更多

的屏幕的代码吗？您需要将

当前用户

传递到

更多

。已更新，请检查，可能是我传递错误，请指导我。是的，没有打印内容。我怎么做？好的。这意味着，

widget？.currentUser？.maxDistance！=null

为真。是吗？请帮帮我。我可以在任何桌子上分享我的屏幕吗。。陷入困境…你从哪里得到这个错误的？`对null调用了getter'maxDistance'。‘好的，当然@GAGANSINGH

  class More extends StatefulWidget{
      final CreateAccountData currentUser;
      More({this.currentUser,}) ;

CreateAccountData currentUser = CreateAccountData();

setState(() {
if(widget?.currentUser?.maxDistance != null){
  if (widget.currentUser.maxDistance > freeR) {
    widget.currentUser.maxDistance = freeR.round();
    changeValues.addAll({'maximum_distance': freeR.round()});
  } else if (
      widget.currentUser.maxDistance >= paidR) {
    widget.currentUser.maxDistance = paidR.round();
    changeValues.addAll({'maximum_distance': paidR.round()});
  }
    distance = widget.currentUser.maxDistance.round();
 } else {
    print('currentUser is null ${widget?.currentUser?.maxDistance}')
 }
});