Append to Kotlin data class ArrayList

Question

I have the following data class intended for use in an Android application running Kotlin version 1.2.51:

data class Data(var a: ArrayList<String>, var b: String)

As you can see, a is an ArrayList. I want to append elements from another array into a. I've tried this:

itemsToAppend.forEach {
    Data.a.add(it)
}

However, Android Studio determines that a is an unresolved reference. How exactly does one append an item to such an ArrayList?

Thanks.

Why are you address a as a static field in the way Data.a ? Your a is a member field, and should be addressed as a Data().a or val data = Data(); data.a. — Demigod
– Demigod, Commented Jul 20, 2018 at 15:00

Suhaib Roomy · Accepted Answer · 2018-07-20 14:58:16Z

2

Data classes are not object classes. You will have to initialise them before you can use it

val d= Data(ArrayList(), "demo")
itemsToAppend.forEach {
    d.a.add(it)
}

answered Jul 20, 2018 at 14:58

Suhaib Roomy

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Comments

user8959091 · Accepted Answer · 2018-07-20 14:58:01Z

1

create an instance of Data:

var a: ArrayList<String> = arrayListOf()
var data = Data(a, "something")

and use data in your loop

answered Jul 20, 2018 at 14:58

user8959091

Comments

Mahdi-Malv · Accepted Answer · 2018-07-20 20:40:35Z

1

If you want to access you list staticly do this:

data class D(var a: ArrayList<String>) { // a can't be used as D.a
   companion object {
      var ab: ArrayList<String> = ArrayList() // ab can be used as D.ab
   }
}

answered Jul 20, 2018 at 20:40

Mahdi-Malv

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