what is the impact of setting `kotlinOptions.jvmTa...

# announcements

[Devin Fee]

what is the impact of setting kotlinOptions.jvmTarget to JavaVersion.VERSION_1_8 or JavaVersion.VERSION_15 – assuming i’m using Java 15?
• (1.4.20 release notes where support for 15 was added)
• (jvmTarget documentation)
will my code run in an optimized manner – as it can take advantage of newer JDK features, etc?

[ephemient]

it only affects the bytecode generated, not how the JVM runs it. you can use newer Java APIs regardless

[ephemient]

the only difference at this point is indified string concat, which isn't enabled unless you use freeCompilerArgs += "-Xstring-concat=..." anyhow

[Devin Fee]

i’m having a discussion elsewhere about which jvmTarget we should select. i’m struggling to understand how to make this decision.

[Devin Fee]

i.e. is 15 less stable than 11 (as it was recently added?) – and should we just use 8, because it’s worked for us so far?

[ephemient]

the only unstable addition is indified string concat and that's off by default, so if you don't turn it on, it doesn't matter whether you pick 8 or 15 if you're running with on Java 15. if you do turn it on, you need to target 15

[Devin Fee]

thank you. is there any additional documentation i should be looking at to further educate myself on the matter?

[ephemient]

targeting Java 8 or above does have the benefit of a better @JvmDefault + delegation behavior, so I wouldn't go below that unless you need to run on older JREs

[ephemient]

you already found the documentation