I'm bumping up version in one of my Android project. I see here <https://developer.android.com/studi...

# android

[Daniele Segato]

I'm bumping up version in one of my Android project. I see here https://developer.android.com/studio/preview/features#jdk-17 that I'm supposed to use JDK 17 now.

But I'm confused
1. Do I set the kotlin toolchain to 17?
2. Am I supposed to also set the jvmTarget to 17?
3. Do I still need the android.compileOptions?
4. Does it mean I don't need desugaring anymore for java.time and the likes?
I think I missed something, can anyone shed some light on this topic? Which is the recommended setup regarding the kotlin / java toolchain on an Android Project using the last AGP 8.1.0-alpha06 and Android Studio Giraffe | 2022.3.1 Canary 6?
Thank you

[Daniele Segato]

@kenkyee asking about your not kotlin reaction: isn't this the #android channel?

[Daniele Segato]

and this is asking about jvmTarget version which kinda is kotlin related

[Daniele Segato]

I think I fall in the description "Using Kotlin to build Android apps". I wanna know if the kotlin compiler with jvm target 17 is going to produce Jar / Dex compatible with the devices

[Daniele Segato]

I don't think there are many things specific to android in "Using Kotlin to build Android apps" other than the build chain and maybe some library

[kenkyee]

Click on the info section up top.
The kotlin compiler works fine with jdk17

[Daniele Segato]

I'm sorry, which info section? I only see 2 pinned messages

Which say:

General kotlin behaviours that should work in anywhere but don't work (to be asked in #android )

Dex is one of the target for android and I'm asking if I can use jdk 17 and target jdk 17 for Android without issues on devices

[kenkyee]

yes and yes for 17..folks have done it

[kenkyee]

you're asking about whether jdk17 works

[Daniele Segato]

I'm asking if I can encounter runtime crashes on missing methods on some older device.

Years ago I recall that targeting JDK greater than 1.8 kotlin used some feature of jdk that wasn't available on devices. One such example, if I recall, was getOrElse for Map. It would compile but than crash at runtime on devices where the jdk didn't have the method.

This is just an example. I just want to know if this could happen setting target jdk 17.

[kenkyee]

that was totally different...you needed to enable desugaring.
But several companies are using JDK17 already including Slack and Google.

[Daniele Segato]

This was before desugaring was a thing.
And I enable desugaring only if I need it (ex. Using java.time).

So what I'm asking here is: will the build targeting android do the right thing or do I have to enable desugaring everywhere?

Cause apparently now we are forced to use jdk 17. If desugaring is mandatory why not including it directly in the build?

[kenkyee]

desugaring is only needed if you use Java17 code...if you only use Kotlin, it won't matter

[Daniele Segato]

So you are saying I'll have to remember which functions are not available in java 8 and avoid using them or enable desugaring.

Example: String.isBlank() is new to java 11. It wasn't there in Java 1.8. As far as I understand it targeting java 11 or 17 tells the compiler that method is available. But at runtime, in Android, it will not be if there:

https://source.android.com/docs/setup/start/older-versions#jdk

Are you saying that kotlin will not map to any method after java 8 when building for Android and will know what to do?

There's not much documentation about this nor on the Kotlin side nor on android side.

[kenkyee]

Kotlin compiler only targets JVM 8 and JVM11 bytecode. It doesn't really know about the Java language

[kenkyee]

you could also just test it...

[Daniele Segato]

Yes, bytecode, sure, but I'm not talking about bytecode, I'm talking about JDK and methods that are available on that JDK level.

I sure can test it out. But I'd feel more confident to have some official statement on this.

[Daniele Segato]

Anyway, do you still think this is not kotlin? Cause that confused me, I don't want to be off topic, but at the same time I don't get how this is :-)

[kenkyee]

This channel is for helping the Jetbrains folks...for issues that Kotlin may have on Android.
It's not a channel for general Android dev questions.

[Daniele Segato]

I see, than I'm definitely off topic.

Do you know if there's a channel where my question would be in-topic in this server?

[kenkyee]

this entire slack server is for jetbrains

[kenkyee]

only the compose channel is a jetbrains/google combo for Jetpack Compose

[Daniele Segato]

Eh, it's the only server I know where sometimes you get answers from googlers :-)

Thanks anyway! I'll look into it myself

[kenkyee]

that's because they take time out of their day and help folks sometimes...it's NOT an official channel

[Daniele Segato]

I know. I do the same thing over in the discord server you linked in the description of this channel.
But there are questions that only them can answer.