Kotlin enum class in Android performance

Question

In Java we are told to strictly avoid using enums on Android because they take up twice the memory.

Does this apply to enum class in Kotlin aswell? Will a Kotlin enum be compiled into a Java enum?

You might be also interested in whether you should really avoid enums on Android or not: https://stackoverflow.com/questions/29183904/should-i-strictly-avoid-using-enums-on-android and https://stackoverflow.com/questions/5143256/why-was-avoid-enums-where-you-only-need-ints-removed-from-androids-performanc — Ilya, Jun 04 '17 at 03:45

Todd · Accepted Answer · 2017-06-04T00:49:51.497

26

It would appear so, yes.

I created this in Kotlin:

enum class Thingies {
    Red,
    Green,
    Blue
}

And decompiled it with javap -v, and here is the header:

public final class Thingies extends java.lang.Enum<Thingies>
minor version: 0
major version: 52
flags: ACC_PUBLIC, ACC_FINAL, ACC_SUPER, ACC_ENUM

Bottom line: they are identical, so you probably have to treat them the same way.

edited Jun 04 '17 at 00:49

answered Jun 03 '17 at 23:30

Todd

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Now folks at Google say its okay to use enums, please check out https://youtu.be/IrMw7MEgADk?t=857 – Rambo7 Jan 11 '19 at 18:06
1

If you Proguard the class, does it turn them into ints? – fahadayaz Jun 25 '19 at 11:55
@Rambo7 - They say it's okay to use enums now but they also say string/int constants are still better. – Bawa May 24 '22 at 21:07

score 6 · Answer 2 · answered Jun 04 '17 at 00:23

6

They are exactly the same thing, a Kotlin Enum is a Java JVM Enum.

answered Jun 04 '17 at 00:23

Jayson Minard

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score 5 · Answer 3 · answered Jan 11 '19 at 18:03

5

You can most definitely use enums in Android now, they specifically discussed this topic in this Google I/O video: https://www.youtube.com/watch?v=IrMw7MEgADk (if you don't want to watch the whole video, then start from 11:30 ish to 14:40).

answered Jan 11 '19 at 18:03

Rambo7

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That video he said that it still isn't as efficient as using an int. Android Framework devs still avoid them for this reason. – phreakhead May 14 '19 at 21:19
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@phreakhead you don't have listened until the 14:40. https://youtu.be/IrMw7MEgADk?t=858 – alexpfx Sep 21 '19 at 02:49
I would recommend watching from 10:15 instead if you have time for that extra minute to get the context: It was comparing dalvik and ART. – Teng-pao Yu Oct 08 '19 at 07:02
2

Yes agree, it's still maybe not as efficient as using int, but still for normal size project, using 10-50 enums will not have that huge impact on your performance and memory, so I would say use ONLY enums and be happy :) – Viktor Apoyan Oct 22 '20 at 09:35

Kotlin enum class in Android performance

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