Hi all, I’m running into an issue with a Kotlin mu...

# multiplatform

[almibe]

Hi all, I’m running into an issue with a Kotlin multi-platform/multi-project (is there a better term for that?) gradle build. Most of the sub-projects are common Kotlin code but the one I’m having issues with is JVM only and I’m trying to make it use the gradle application plugin. At first, I tried to just get a simple “Hello, World” application working and I got that working after I realized that besides including the application plugin and configuring the main class I also needed the following:

tasks.named<JavaExec>("run") {
  dependsOn(tasks.named<Jar>("jvmJar"))
  classpath(tasks.named<Jar>("jvmJar"))
 }

Now the simple app works when I do gradle run, but when I depend on code from other sub-projects that are just common code when I run the application I get java.lang.NoClassDefFoundError exceptions for the classes from the common sub-projects. (gradle check runs fine btw)
I’m assuming this is an issue with how I have the application plugin setup, but I’m not sure what changes need to be made.

[mbonnin]

I'd recommend using the "application" plugin with "org.jetbrains.kotlin.jvm" (and not "org.jetbrains.kotlin.multiplatform" )

[mbonnin]

Not sure the "application" plugin work with the Kotlin mutliplatform one. I've had issues with tihs in the past

[mbonnin]

Might be doable but it seems less straightforward than the JVM only thing

[almibe]

Okay I'll try that, it didn't occur to me that I could have some projects multi-platform and others just jvm, but that makes sense. Thanks.

[almibe]

Cool that worked, thanks again!

[Oliver.O]

Just for the record: You can use the application plugin with multiplatform, but you have to add withJava() in the kotlin.jvm() block to work around https://youtrack.jetbrains.com/issue/KT-42683.

Actually, you don't even need the application plugin, and without it, you can have more than one executable JVM target. For example, configuring it this way runs backendJvm and frontendJvm targets:

tasks {
    @Suppress("UNUSED_VARIABLE")
    val runBackendJvm by creating(JavaExec::class) {
        group = "application"
        mainClass.set("MainKt")
        jvmArgs = backendJvmArgs
        with(kotlin.targets["backendJvm"].compilations["main"] as KotlinJvmCompilation) {
            classpath = output.allOutputs + runtimeDependencyFiles
        }
    }

    @Suppress("UNUSED_VARIABLE")
    val runFrontendJvm by creating(JavaExec::class) {
        group = "application"
        mainClass.set("MainKt")
        with(kotlin.targets["frontendJvm"].compilations["main"] as KotlinJvmCompilation) {
            classpath = output.allOutputs + runtimeDependencyFiles
        }
    }
}