Kotlin 什么是开放式property为什么我不能将其设置器设为private私有

发布于07月18日

What is the difference between a Property and Open Property in Kotlin? The code below complains on me declaring the setter private and Intellij says private setters are not allowed for open properties. What is an open property?

@RestController
open class ParameterController {

  @Autowired
  lateinit var parameterRepository: ParameterRepository
    private set //error


}

为什么上面的代码无效，而这个代码无效？

open class ItemPrice{

    lateinit var type: String
        private set // ok

}

EDIT: I am using the spring-allopen plugin, and marking the class explicitly as open doesn't make a difference.

推荐答案

What is an open property?

A open property that means its getter/setter(?) is not final. On the other hand, its getter & setter can be override by its subclasses.

In kotlin, everything is declared with final keyword except interface, annotation class, sealed class, enum class, variables, mutable property backing field and parameters, but the immutable variables & parameters are effectivily-final.

Due to the allopen plugin will makes all of the properties & methods opened in the spring components.

However, a open property can't to makes a private setter, if the property is opened, for example:

//v--- allopen plugin will remove all `final` keyword, it is equivalent to `open`
open var value: String=""; private set
//                         ^--- ERROR:private set are not allowed

因此，必须明确地将属性设置为final，例如:

//v--- makes it final explicitly by `final` keyword
final var value: String =""; private set

Kotlin 什么是开放式property为什么我不能将其设置器设为private私有

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