FunctionalJava 5.x uses Java 8. Future releases will follow the Java long term support model, the future series 6.x uses Java 11 and 7.x uses Java 17.
The FunctionalJava 4.x series uses the Retro Lambda project to backport Java 8 lambdas to Java 6 bytecode. This requires access to both JDK 6 and 8. The build system requires the environment variables
JAVA8_HOME to refer to the appropriate directories.
Building is done using Gradle. In the root directory run:
This will download the Gradle build tool and necessary dependencies and build FunctionalJava.