Re: RFC: help me with Java enums please

[Akim Demaille]

Hi Paul!

> Le 4 avr. 2020 à 19:34, Paul Eggert <address@hidden> a écrit :
> 
> On 4/4/20 12:12 AM, Akim Demaille wrote:
>> The JVMs are known to be quite good at optimizing, but I have no idea 
>> whether this abstraction will be zero-cost or not.
> 
> Although I'm no Java expert,

Thanks for accepting taking a trip in Javaland :)

> a quick bit of Googling suggests that JVMs don't deal with enums quite as 
> efficently as they do with ints. See, for example:
> 
> https://developer.android.com/topic/performance/reduce-apk-size
> 
> which says: "Avoid enumerations. A single enum can add about 1.0 to 1.4 KB of 
> size to your app's classes.dex file. These additions can quickly accumulate 
> for complex systems or shared libraries. If possible, consider using the 
> @IntDef annotation and code shrinking to strip enumerations out and convert 
> them to integers. This type conversion preserves all of the type safety 
> benefits of enums."

This sounds rather convincing.  However,

> Have you considered using @IntDef instead?

AFAICT @IntDef is Android only, it's not part of standard Java.
https://developer.android.com/reference/kotlin/androidx/annotation/IntDef

Cheers!