意味着 Dart 系统无法正确表达您想要使用的类型: void setEmail(dynamic email) { if (email is Email) { _email = email; } else if (email is String) { _email = new Email.fromString(email); } } 由于Dart 目前不支持联合类型,因此无法表达类型 Email | String,因此我们被迫使用 dynamic 来接...
Map.forEach()从Map返回key-value对。它期望返回一个String, dynamic，而不是一个动态值。这就是...
type https://dartpad.dartlang.org/ voidmain() {// abstract class String implements Comparable<String>, PatternStrings ="string type";print(s);// String s// Number n = 123;// Error: 'Number' isn't a type.inti =123;// Number, int iprint(i);doubled =3.1415926;// Number, double ...
Dart Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'Iterable<Map<dynamic, dynamic>>' in type cast, stack trace: #0 UserModel._convertCartItems (package:test_app/model/user.dart:67:31) E/flutter (30545): #1 new UserModel.fromSnapshot (package:test_app/model/user.d...
Dart语法问题type ‘List<dynamic>‘ is not a subtype of type ‘List<DiskFile>‘ 技术标签: Flutter flutter1.错误type ‘List’ is not a subtype of type ‘List’:报错就是说你list是动态类型,说明你list没有泛型 2.错误描述: 首先定位到了这个地方发现传入的_diskFiles这个参数有问题。 后面我去找了...
() 方法,所以建议大家在编程时不要直接使用dynamic;var: 是一个关键字,意思是"我不关心这里的类型是什么",系统会自动判断类型 runtimeType;object: 是Dart 对象的基类,当你定义: object o =xxx ;时这个时候系统会认为o 十个对象,你可以调用o的toString()和hashCode()方法因为Object 提供了这些方法,但是如果你...
dynamic 数据类型 : dynamic 是 Drat 语言中的 动态数据类型 , 通过 dynamic 关键字定义的变量 , 在 ...
Dart does not infer the return type of a function or getter in cases where it seems like it should. When it doesn't infer the type, instead of giving you an error, it silently gives you dynamic, which is probably not what you want. Point 2. is a vestige of Dart 1.0's optional t...
Error: The argument type 'dynamic Function(Provider<dynamic>)' can't be assigned to the parameter type 'T Function<T>(Provider<T>)'. I believe that this behavior is incorrect, since Dart can actually infer the correct types on the calling site, meaning thatfoo.provide(StringProvider())does...
这个错误基本上是因为你从数据库中接收到一系列的数据，你试图把它们作为一个数据来分配，这是不可能的...