How to access `java.home` being used by Gradle?

Question

./gradlew properties shows no properties having the value of ${JAVA_HOME} and the following emit an error indicating no such property exists:

println org.gradle.java.home
println gradle.java.home
println java.home

In the end, I want to specify a compile-time dependency on the tools.jar that's part of the JDK. For example:

dependencies {
  compile files("${java.home}/lib/tools.jar")
}

Answer 1

println System.properties['java.home']

Answer 2

It's not very well documented from what I can find, but you can use the Jvm object in Gradle like this:

println org.gradle.internal.jvm.Jvm.current().getJavaHome()

There's a discussion thread here that shows a couple other usages.

Plus, if you just want to address the tools jar, you can use

org.gradle.internal.jvm.Jvm.current().toolsJar

Answer 3

If you wish to set the JAVA_HOME used by Gradle you can setting the environment property:

org.gradle.java.home

Specifies the Java home for the Gradle build process. The value can be set to either a jdk or jre location, however, depending on what your build does, jdk is safer. A reasonable default is used if the setting is unspecified.

If you are trying to reference the existing JAVA_HOME being used, you can gain access to the System Environment properties in this way:

java.home = "$System.env.JAVA_HOME"