Release Notes

This plugin makes sure that Gradle is using a specific JDK, provided by SDKMAN!, to build your project.

It does not run SDKMAN! itself, it only checks if the Java version you expect is being used (as explained below).

Because SDKMAN!’s JDK identifiers includes both a Java version and a vendor, with this plugin you can guarantee that your project will be compiled and tested against a specific JDK, like 11.0.2-open or 11.0.8.fx-zulu.

What does this Plugin check

This plugin checks the following:

• the project contains a sdk env file .sdkmanrc.
• the .sdkmanrc specifies a java property with a SDKMAN! JDK identifier.
• the Gradle process is running the JDK specified by .sdkmanrc.
• The JAVA_HOME environment variable is pointing to the same JDK.
• the project’s sourceCompatibility is compatible with the JDK being used.

This ensures that you never try to build your project with the wrong JDK, which can cause build errors, or worse, releasing a project that was tested on a different JVM.

Applying this Plugin

Check for the latest version on the top of this page, or in the Gradle Plugins Portal.

Add this plugin to your plugins block:

plugins {
    id "com.athaydes.sdkman" version "<version>"
}

Or using the older syntax:

buildscript {
  repositories {
    maven {
      url "https://plugins.gradle.org/m2/"
    }
  }
  dependencies {
    classpath "gradle.plugin.com.athaydes.gradle:sdkman-gradle-plugin:<version>"
  }
}

apply plugin: "com.athaydes.sdkman"
apply plugin: 'java'

Requirements

• Gradle 5.0+
• Java 8+

Usage

You only need to apply this plugin to your project in order to use it.

There’s currently no configuration.

Because this plugin won’t run sdk for you, you’re expected to run it manually, or automate it in your CI.

For usage with GitHub Actions, see the specific section about it.

Example workflow:

cd my-project
sdk env           # load the JVM specified in .sdkmanrc
./gradlew build

Notice that sdk env is only required if you did not enable SDKMAN!’s sdkman_auto_env property to true. See SDKMAN! Config for instructions on setting properties.

The value this plugin provides is that if you forget to run sdk env, your build will fail, preventing you from making mistakes.

Examples

Please find a few examples inside the examples directory.

Tasks

• checkJavaVersion - checks that the Java versions (env, sys props, sourceCompatibility) all match.
• enforceSdkManRc - enforces that the Java home matches the .sdkmanrc JDK identifier.

Dependency graph:

AbstractCompile (all tasks of type)
    dependsOn enforceSdkManRc
        dependsOn checkJavaVersionTask

Because all compilation tasks depend on this plugin’s tasks, you should never need to run this plugin’s tasks explicitly (but you can, if you want).

If anything goes wrong, the build fails with an error explaining what’s wrong in detail.

Using SDKMAN in GitHub Actions

To run your builds in a CI (Continuous Integration system), you’ll need to get SDKMAN! to manage your Java versions also in your CI environment.

If you use GitHub Actions, the setup-java-sdkman action can be used for that.

See this project’s CI Workflow for an example!

Using this plugin and setup-java-sdkman you ensure your builds and tests always run with the exact Java version you want, locally and in CI.