Examples here don't seem to work: https://docs.gradle.org/current/userguide/toolchains.html

def launcher = javaToolchains.launcherFor {
    languageVersion = JavaLanguageVersion.of(23)
}

tasks.named('anotherSampleTask') {
    javaHome = launcher.map { it.metadata.installationPath }
}

I don't get something I can use as a path to Java Home.

Can you elaborate? What does not work? What did you get? Can you share an MCVE?

Fwiw, this snippet comes from a real project: https://github.com/gradle/gradle/blob/master/platforms/documentation/docs/src/snippets/java/toolchain-config-task/groovy/build.gradle which is exercised during builds: https://ge.gradle.org/s/qk25c6grt526u/tests/task/:docs:docsTest/details/org.gradle.[…]task_groovy_toolchainConfigTaskJavaHome.sample?top-execution=1

I attempted to quickly hack together a task that calls `jlink`(I realize this isn't the best way to do this, it's just an example):

def launcher = javaToolchains.launcherFor {
    languageVersion = JavaLanguageVersion.of(23)
}

task jlink(type:Exec) {
    def javaHome = launcher.map { it.metadata.installationPath }
    commandLine "${javaHome}/bin/jlink", "--help"
}

This results in an error:

> A problem occured starting process 'command 'map(map(provider(?) (with side effect org.gradle.jvm.toolchain.internal.DefaultJavaToolchainService$$Lambda/0x000001929b9ef6b8@4a4d92c8)))/bin/jlink''

launcher.map

leaves you with a provider, you need to

.get()

it to get the actual value

Thank you. A more complete example would also have helped 😄 . Migrating build scripts to a new language is a big disruptive change. I will eventually get there, but I don't use IntelliJ or Android Studio, I've tried IntelliJ, but I just don't like it. I use NetBeans, which is great for Gradle/Java, but less so for Kotlin.

From the doc you linked:

WARNING

The examples above use tasks with RegularFileProperty and DirectoryProperty properties which allow lazy configuration. Doing respectively launcher.get().executablePath, launcher.get().metadata.installationPath or compiler.get().executablePath instead will give you the full path for the given toolchain but note that this may realize (and provision) a toolchain eagerly.

I read it, I just didn't fully appreciate what it was saying, it was particularly confusing as that

get()

in the warning is placed before the

.metadata.installationPath

so intuitively I thought the

map { it.metadta.installationPath }

was handling it.

myProvider.map { it.foo }.get()

==

myProvider.get().foo

How would my jlink example work while avoiding calling

get()

?

Probably many ways. One would be to not make a task of type

Exec

, but instead use

exec { ... }

at execution time