Hi everyone! I’m newbie in KMP. Started project from scratch. Documentation says that KMP projects ...

# multiplatform

[Vladislav Ermolin]

Hi everyone!
I’m newbie in KMP. Started project from scratch.

Documentation says that KMP projects are getting dependency on kotlin-stdlib automatically. However, for some reason, I can’t access StringBuilder in my commonsMain source set. At the same time I’ve added a couple of KMP libraries as dependencies to the commonsMain set explicitly and all entities from them are accessible.

I feel like I’m making some stupid mistake. But I can’t find which one. Any idea what might’ve gone wrong?

[Michael Krussel]

Do you get a compiler error or do you get an error just in the IDE?

[Vladislav Ermolin]

I don’t know. However, I imported a couple of other KMP projects and there StringBuilder is accessible just fine.

My IDE is IDEA, it complains on “unresolved reference”.

[Vladislav Ermolin]

For some reason the issue is gone if I add linux64 target. But I only need JVM. Besides, the other libraries, which I use as a reference, do not have such problem.

[Michael Krussel]

Does gradle build successfully or does it show a compiler error with an unresolved reference?

[Kuba Petržílka]

Mine issue below this thread is probably related, because I cannot see JsExport neither StringBuilder in commonMain sources while it works in the jsMain and jvmMain sources

[Kuba Petržílka]

@Michael Krussel it shows a compiler error:

e: file:///home/kubapet/Projects/dossier-profile-gradle/dossierprofile-publicapi-restapi/src/commonMain/kotlin/AwesomeClass.kt:1:2 Unresolved reference: JsExport

and as Vladislav says the other ilbraries added as commonMain dependencies are accessible from there it is only related to the stdlib

[Kuba Petržílka]

Oh ye, there is some regression in 1.9.10 -> 1.9.20;
when I add this dependency explicitly, then it works

commonMain.dependencies {
      implementation("org.jetbrains.kotlin:kotlin-stdlib-common:1.9.10") {
        version {
          strictly("1.9.10")
        }
      }

but

commonMain.dependencies {
      implementation("org.jetbrains.kotlin:kotlin-stdlib-common:1.9.20") {
        version {
          strictly("1.9.20")
        }
      }

does not...
maybe related to the migration of kotlin-stdlib-common to just kotlin-stdlib?
@Vladislav Ermolin can you verify that it is the case even on your end?

[Vladislav Ermolin]

Nope, doesn’t help me. Only addition of linux64 target in addition to jvm solves the issue.

[Vladislav Ermolin]

@Michael Krussel ./gradlew build manages to compile the code, while IDE shows Unresolved reference.

[Kuba Petržílka]

which version are you using though?

[Vladislav Ermolin]

2024.1

[Vladislav Ermolin]

Just started out writing jvm target code and found out that any attempt to access java package inside of the jvmMain also gives unresolved reference.
> Unresolved reference: java
However, in this case project does not compile as well.

[Vladislav Ermolin]

Solved by switching Java SDK to another version in Project Structure dialog. However, it made <http://java.net|java.net> classes accessible also in commonMain target.

[Kuba Petržílka]

I meant which version of kotlin-stdlib 🙂

[Vladislav Ermolin]

It’s 1.9.23. But switching back to 1.9.10 didn’t make the StringBuilder available in commonMain
https://kotlinlang.slack.com/archives/C3PQML5NU/p1714238818888659?thread_ts=1714145071.665529&cid=C3PQML5NU

[Vladislav Ermolin]

Only changing the JDK helped, but it introduced the opposite problem - I can now access java classes in commonMain, which I guess must not be allowed.

[Kuba Petržílka]

yeh, that sounds wrong

[Vladislav Ermolin]

For the record:
• I’m using official library project template
• I’m using completely fresh installation of the latest IDEA from Toolbox
• I’m using JDK from the Android Studio installation, which is JBR 17. But I tried other JDKs and result was the same.
• My architecture is arm64

[Michael Krussel]

@Vladislav Ermolin If your only target is jvm then you can access Java classes from commonMain. You can access anything that is in all the targets you are targetting.

I don't know why the IDE is showing you an error when it actually compiles. I've encountered a lot of different IDE bugs with KMP over the years. Sometimes doing the invalidate cache stuff and restarting Intellij helps sometimes it doesn't. Best solution is normally to try and find a work around like changing the Java SDK version and filing a bug with JetBrains.

[Vladislav Ermolin]

You can access anything that is in all the targets you are targetting.

Indeed, makes sense.

[Vladislav Ermolin]

BTW, I’ve found a difference between 2 JVMs I used. For some reason that “other JBR 17”, which was causing an issue, shows “empty” classpath in the project structure dialog. Like if the installation were corrupted or smth like that.

[Vladislav Ermolin]

Thanks everyone for the help! I think my issue is solved.