如果dart是静态类型语言，那么"dynamic“关键字是如何工作的？

Question

据我所知，对于静态类型，数据类型在编译时已知，对于动态类型，数据类型在运行时已知/评估。

Dart文档(https://dart.dev/faq#q-is-dart-a-statically-typed-language)说dart是一种静态类型的语言-

Q. Is Dart a statically typed language?
Yes, Dart 2 is statically typed. For more information, read about Dart’s type system.

With its combination of static and runtime checks, Dart has a sound type system, which guarantees that an expression of one type cannot produce a value of another type. No surprises!

Even with type-safe Dart, you can annotate any variable with dynamic if you need the flexibility of a dynamic language. The dynamic type itself is static but can contain any type at runtime. Of course, that removes many of the benefits of a type-safe language for that variable.

那么，我们如何能够分配一个变量“动态”数据类型，这使得类型评估在运行时？

Answer 1

简单地说，dynamic 是，它本身就是一种类型。它只是将类型检查移到运行时(如您引用的文本中所提到的)。

这允许您执行像final Map<String, dynamic> json = await fetchData();这样的操作，否则这是不可能的。

请注意，Dart强烈不鼓励使用dynamic类型，特别是因为它的运行时影响和缺乏“静态性”。

Answer 2

动态是其中一种类型。

因此，如果要使用动态变量，则必须将其转换为其他类型。