问题

open class OpenBase(open val value: Int)

interface AnotherExample {
    val anotherValue: OpenBase
}

open class OpenChild(value: Int) : OpenBase(value), AnotherExample {
    override var value: Int = 1000
        get() = field - 7
    override val anotherValue: OpenBase = OpenBase(value)
}

open class AnotherChild(value: Int) : OpenChild(value) {
    final override var value: Int = value
        get() = field
        set(value) { field = value * 2 }
    final override val anotherValue: OpenChild = OpenChild(value)
}

fun main() {
    val openChild = OpenChild(42)
    println("OpenChild value: ${openChild.value}")
    println("OpenChild anotherValue: ${openChild.anotherValue.value}")

    val anotherChild = AnotherChild(42)
    println("AnotherChild value: ${anotherChild.value}")
    println("AnotherChild anotherValue: ${anotherChild.anotherValue.value}")
    
    anotherChild.value=69 //HERE
    println("AnotherChild value: ${anotherChild.value}")
    println("AnotherChild anotherValue: ${anotherChild.anotherValue.value}")
}

在您的Kotlin代码中，您在AnotherChild类中使用了final关键字来覆盖了value属性。尽管value属性在其父类OpenChild中具有自定义的getter和setter方法，但您仍然可以在子类中使用final关键字覆盖它。

final关键字在Kotlin中用于防止子类进一步覆盖属性或方法。在AnotherChild类中，虽然您覆盖了value属性，但由于您使用了final关键字，它将变得不可再被子类覆盖。这意味着您可以在AnotherChild类中修改value属性的行为，但不能在后续的子类中再次覆盖它。

因此，尽管value属性在OpenChild中有自定义的getter和setter，但在AnotherChild中，您仍然可以修改它的行为，并且不会出现错误。这是因为final关键字阻止了进一步的覆盖。

open class OpenBase(open val value: Int)

interface AnotherExample {
    val anotherValue: OpenBase
}

open class OpenChild(value: Int) : OpenBase(value), AnotherExample {
    override var value: Int = 1000
        get() = field - 7
    override val anotherValue: OpenBase = OpenBase(value)
}

open class AnotherChild(value: Int) : OpenChild(value) {
    final override var value: Int = value
        get() = field
        set(value) { field = value * 2 }
    final override val anotherValue: OpenChild = OpenChild(value)
}

fun main() {
    val openChild = OpenChild(42)
    println("OpenChild value: ${openChild.value}")
    println("OpenChild anotherValue: ${openChild.anotherValue.value}")

    val anotherChild = AnotherChild(42)
    println("AnotherChild value: ${anotherChild.value}")
    println("AnotherChild anotherValue: ${anotherChild.anotherValue.value}")
    
    anotherChild.value=69 //HERE
    println("AnotherChild value: ${anotherChild.value}")
    println("AnotherChild anotherValue: ${anotherChild.anotherValue.value}")
}

答案1

得分: 1

The final in final override var value only means that the property can't be overridden in other subclasses. If you want value to be read-only in AnotherChild, you must declare it as val instead of var. Or, if you do need a private setter, declare it as var but add private to set.

In the context of class members, val simply means "property with a getter," and var means "property with a getter and a setter." The latter is a valid override for the former, which is what you are doing in AnotherChild.