How do I tell Gradle to use specific JDK version?

Question

I can't figure out to get this working.

Scenario:

• I have an application built with gradle
• The application uses JavaFX

What I want

• Use a variable (defined per developer machine) which points to an installation of a JDK which will be used for building the whole application / tests / ...

I thought about having the gradle.properties file, defining the variable. Something like

JAVA_HOME_FOR_MY_PROJECT=<path to my desired JDK>

What I don't want

• point JAVA_HOME to the desired JDK

I could live with many suggestions:

• a solution that defines a system environment variable which I'm able to check in my build.gradle script
• a variable defined in gradle.properties
• overriding the JAVA_HOME variable only for the build context (something like use JAVA_HOME=<my special JDK path defined somewhere else defined>)
• something else I didn't think about

Question:

• How to wire a variable (how ever defined, as variable in the gradle.properties, system environment variable, ...) to the build process?

I have more than one JDK7 available and need to point to a special version (minimum JDK_u version).

Any answer is appreciated and I'm thankful for every hint to the right direction.

Answer 1

there is a Gradle plugin that download/bootstraps a JDK automatically:

https://plugins.gradle.org/plugin/com.github.rmee.jdk-bootstrap

No IDE integration yet and a decent shell required on Windows.

Answer 2

As seen in Gradle (Eclipse plugin)

http://www.gradle.org/get-started

Gradle uses whichever JDK it finds in your path (to check, use java -version). Alternatively, you can set the JAVA_HOME environment variable to point to the install directory of the desired JDK.

---

If you are using this Eclipse plugin or Enide Studio 2014, alternative JAVA_HOME to use (set in Preferences) will be in version 0.15, see http://www.nodeclipse.org/history

Answer 3

If you add JDK_PATH in gradle.properties your build become dependent on on that particular path. Instead Run gradle task with following command line parametemer

gradle build -Dorg.gradle.java.home=/JDK_PATH

This way your build is not dependent on some concrete path.

Answer 4

If you are using linux and gradle wrapper you can use following solution.

Add path to local.properties file:

javaHome=<path to JDK>

Add to your gradlew script file:

DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
source $DIR/local.properties 2>/dev/null

if ! [ -z "$javaHome" ]
then
  JAVA_HOME=$javaHome
fi

In this solution, each developer can set his own JDK path. File local.properties shouldn't be included in version control system.