In kotlin, how to make the setter of properties in primary constructor private?

Question

class City(val id: String, var name: String, var description: String = "") {

    fun update(name: String, description: String? = "") {
        this.name = name
        this.description = description ?: this.description
    }
}

I want the setter of properties name to be private, and the getter of it public, how can I do?

check it https://kotlinlang.org/docs/reference/properties.html — Nandkishor mewara, Jun 07 '17 at 06:55
https://stackoverflow.com/questions/40438571/kotlin-understanding-getters-and-setters — Nandkishor mewara, Jun 07 '17 at 06:56

score 36 · Accepted Answer · edited Aug 22 '18 at 20:25

36

The solution is to create a property outside of constructor and set setter's visibility.

class Sample(var id: Int, name: String) {

    var name: String = name
        private set

}

Update:
They're discussing it here: https://discuss.kotlinlang.org/t/private-setter-for-var-in-primary-constructor/3640

edited Aug 22 '18 at 20:25

Dr.jacky

3,341
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91

answered Jun 07 '17 at 07:39

Miha_x64

5,973
1
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63

score 0 · Answer 2 · answered Jun 07 '17 at 06:45

0

You can try like this

class Sample(var id: Int, private var name:String) {

    // Backing field
    var _name: String = ""
        get() = name
        private set

}

fun main(args: Array<String>) {
     println("Hello World")

     val sample = Sample(1, "hello")
    //    println(sample.name); It's not possible
    println(sample._name)
}

answered Jun 07 '17 at 06:45

VinayagaSundar

1,673
17
18

1

I think would switch the naming though. `_name` in the constructor, and `name` for the property. – marstran Jun 07 '17 at 07:12
You will end up having two names. After `_name`'s `set`, `get`'s return value won't change. – Miha_x64 Jun 07 '17 at 07:35
Adding secondary constructor may be a better solution – Joshua Yan Jun 07 '17 at 07:35
As @Miha_x64 points out, you have to implement the setter of the "backing field" so that it changes the constructor field. – marstran Jun 07 '17 at 08:32

In kotlin, how to make the setter of properties in primary constructor private?

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