How to initiate a fixed size array in data class

Question

I tried to research it but didn't find an answer. I'm creating a data class and in that class I would like to create an array with a fixed size. I tried the following 3 options:

data class User (
    val profilePics = arrayOf("a", "b", "c")
)

data class User (
    val profilePics: Array<String>(3)
)

data class User (
    val profilePics = arrayOfNulls<String>(3)
)

But none of them work. This does work however:

data class User (
    val profilePics: Array<String>
)

How can I initialize a fixed-size strings array inside a data class

Does this answer your question? [What's the Kotlin equivalent of Java's String\[\]?](https://stackoverflow.com/questions/44239869/whats-the-kotlin-equivalent-of-javas-string) — Ori Marko, Dec 24 '19 at 09:41
When you are trying to make fixed size array, there is possibility you don't need array at all - just make 3 separate fields. — Ircover, Dec 24 '19 at 10:50
Also note that arrays in a data class' primary constructor properties are compared by reference during the equality checks, not by content. For that reason, you may want to use a collection or a custom data structure instead of an array. — hotkey, Dec 24 '19 at 17:12

Khalid Saeed · Answer 1 · 2019-12-24T09:58:39.170

1

Use this :

var list:ArrayList <String> = ArrayList(5)

edited Dec 24 '19 at 09:58

answered Dec 24 '19 at 09:35

Khalid Saeed

131
2
8

Thanks Khalid it's working now I upvoted your answer – sir-haver Dec 24 '19 at 10:11

Robby Cornelissen · Accepted Answer · 2019-12-24T09:47:59.190

1

You need type annotations on your value parameters.

The following two will compile just fine:

data class User (
    val profilePics: Array<String> = arrayOf("a", "b", "c")
)

data class User (
    val profilePics: Array<String?> = arrayOfNulls<String>(3)
)

Of course, nothing prevents the caller from passing in differently sized arrays when creating instances of any of these data classes:

val user = User(arrayOf("a", "b", "c", "d")) // compiles fine

edited Dec 24 '19 at 09:47

answered Dec 24 '19 at 09:39

Robby Cornelissen

91,784
22
134
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Thank you very much Robby it's working and it's interesting to know that you can pass different sizes – sir-haver Dec 24 '19 at 09:51

score 1 · Answer 3 · answered Dec 24 '19 at 10:10

1

try this - hope this help var array = Array(2){i ->1}

or

var array = arrayOf(1,2,3) // you can increase the size too

answered Dec 24 '19 at 10:10

Dipankar Baghel

1,932
2
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How to initiate a fixed size array in data class

3 Answers3