I'm having trouble with the jvmRun gradle task. I ...

# multiplatform

[Zyle Moore]

I'm having trouble with the jvmRun gradle task. I feel like I'm missing something simple, so I'm probably missing something in the lingo. My goal is to simply run the main method in the JVM Target, and pass args to it. I've found stackoverflow answers talk about just running main , or passing args from the gradle command line to the gradle task, or using the java or application plugins, or making an executable fatjar, or setting system properties. None of which I feel like should be necessary to just do what's already working (jvmRun) with some args.

[Zyle Moore]

This is what I get when I try to run it "normally" in my mind.

zymus@abyss:~/github/cultoftheancestormoth$ ./gradlew :cotam:jvmRun -DmainClass=games.studiohummingbird.cultoftheancestormoth.CotamKt

> Task :cotam:jvmRun
Usage: cotam [<options>] <command> [<args>]...

Options:
  -h, --help  Show this message and exit

Commands:
  drudge
  librarian
  adept
  example
  load

BUILD SUCCESSFUL in 1s
6 actionable tasks: 1 executed, 5 up-to-date

[Zyle Moore]

And when passing an arg (load)

zymus@abyss:~/github/cultoftheancestormoth$ ./gradlew :cotam:jvmRun -DmainClass=games.studiohummingbird.cultoftheancestormoth.CotamKt load

FAILURE: Build failed with an exception.

* What went wrong:
Task 'load' not found in root project 'cultoftheancestormoth' and its subprojects.

* Try:
> Run gradlew tasks to get a list of available tasks.
> For more on name expansion, please refer to <https://docs.gradle.org/8.6/userguide/command_line_interface.html#sec:name_abbreviation> in the Gradle documentation.
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at <https://help.gradle.org>.

BUILD FAILED in 931ms

[Sebastian Schuberth]

Maybe https://kotlinlang.org/docs/whatsnew2120.html#kotlin-multiplatform-new-dsl-to-replace-gradle-s-application-plugin helps?

[Zyle Moore]

Hmm, that seems to bring me to the same position. It allows be to create an entrypoint to main correctly, but I still can't see how to pass any args to that main.

[Sebastian Schuberth]

I was assuming (but haven't tried) that it works like for Gradle's standard application plugin, so you pass args to the task via --args="options for main" task option.

[tapchicoma]

In the new dsl you could use applicationDefaultJvmArgs to pass arguments for the main function

[tapchicoma]

jvmRun task is mostly needed for the IDE to run random code from the given project

[Sebastian Schuberth]

So there is no task option provided by jvmRun for that purpose?

[tapchicoma]

in form of Gradle property - no. Though the task has args input to configure run arguments.

[Sebastian Schuberth]

Yeah, that's what I mean. Not Gradle properties, but Gradle task specific options, see https://docs.gradle.org/current/userguide/custom_tasks.html#sec:declaring_and_using_command_line_options

[Zyle Moore]

It looks like --args="load" worked for me. Using applicationDefaultJvmArgs doesn't seem to pass to main, as I get the same result as the failure case above.

Not working

kotlin {
    jvm {
        @OptIn(ExperimentalKotlinGradlePluginApi::class)
        binaries {
            executable(KotlinCompilation.MAIN_COMPILATION_NAME) {
                mainClass.set("games.studiohummingbird.cultoftheancestormoth.CotamKt")
                applicationDefaultJvmArgs.set(listOf("load"))
            }
        }
    }
}

Working

zymus@abyss:~/github/cultoftheancestormoth$ ./gradlew :cotam:runJvm -DmainClass=games.studiohummingbird.cultoftheancestormoth.CotamKt --args="load"

[tapchicoma]

the error was because JDK could not find "load" class?

[tapchicoma]

yeah, I was wrong - applicationDefaultJvmArgs passes arguments to the java rather then to the application itself. Though --args="load" should also work for runJvm task.

[Zyle Moore]

I believe it's a doing-the-wrong-thing-in-the-wrong-scope issue on my end.

Specifically, if my build.gradle.kts contains

kotlin {
    jvm {
        @OptIn(ExperimentalKotlinGradlePluginApi::class)
        binaries {
            executable(KotlinCompilation.MAIN_COMPILATION_NAME) {
                mainClass.set("games.studiohummingbird.cultoftheancestormoth.CotamKt")
            }
        }
    }
}

And I run
./gradlew :cotam:runJvm load
It tries to interpret "load" as another gradle command, but there isn't one. It's intent was to be an arg to the main pointed to by :cotam:runJvm .

But running ./gradlew :cotam:runJvm --args="load", it does what I need.

[tapchicoma]

Generally you should be able to configure returned by executable() DSL JavaExec task with your arguments. But if you would like to see such an option in the executable DSL itself - please open a new Kotlin issue

[Zyle Moore]

I did try going down a configuring the existing task option, but then gradle started telling me conflicting information. Running ./gradlew tasks would show jvmRun , but trying to use a tasks.named<JavaExec>("jvmRun") kept throwing an error that the task didn't exist, so I presumed I was also doing something wrong there.