Java/JVM¶

The Java/Jvm package provides some utilities to work with JVM projects:

Manage the JVM version used in the KISSB script or in the terminal using scala coursier
Package simple java applications as JAR, Jlinked runtimes or Docker image (this is incomplete and experimental)

The main usage of this package at this moment is the management of required Java version, since most tools are tied to Maven or Gradle usage, appart from Scala which can be used fully in KISSB thanks to the Bloop standard tooling configuration file.

package require kissb.java

JVM Installation and Selection¶

To select a JVM in a build file, or globally, just set the jvm.default.version variable.

JVM selection and installation is done via the Scala coursier tool, which offers packages for most vendors. You can list them with the following command:

$ ./kissbw .coursier.listJvm

To select the Java version in a Build File:

kissb.tcl

# For openjdk 25
vars.set jvm.default.version 25 
# For IBM OpenJ9 
vars.set jvm.default.version semeru-25

To test a version selection, you can also override the variable via environment, for example for IBM OpenJ9 25 or Temurin 25:

$ JVM_DEFAULT_VERSION=ibm-semeru:25 ./kissbw .jvm.java --version
$ JVM_DEFAULT_VERSION=25 ./kissbw .jvm.java --version

Terminal JVM Selector¶

You can also use KISSB as a JVM selector in the terminal, to do so, you can use the utility that selects the JVM version and exports the environment variables for the terminal, PATH and JAVA_HOME.

This method works best if you have installed Kissb globally in your user space.

To inspect the produced environment for Bash:

$ JVM_DEFAULT_VERSION=ibm-semeru:25 ./kissbw -q .jvm.bashEnv
export JAVA_HOME="/home/xxx/.cache/coursier/arc/https/github.com/ibmruntimes/semeru25-binaries/releases/download/jdk-25.0.1%252B8_openj9-0.56.0/ibm-semeru-open-jdk_x64_linux_25.0.1_8_openj9-0.56.0.tar.gz/jdk-25.0.1+8"
export PATH="/home/xxx/.cache/coursier/arc/https/github.com/ibmruntimes/semeru25-binaries/releases/download/jdk-25.0.1%252B8_openj9-0.56.0/ibm-semeru-open-jdk_x64_linux_25.0.1_8_openj9-0.56.0.tar.gz/jdk-25.0.1+8/bin:$PATH"

To select the JVM in the terminal, the best is to create a function to which you can pass the version:

.bashrc

kissb_select_jvm () { eval $(kissb -q .jvm.bashEnv $*); }

$ kissb_select_jvm --version 21 
$ java --version

Java Package Variables¶

Before or after Loading a flow, you can set configuration variables:

package require kissb.java

vars.set CONFIGURATION VALUE

Variable	Description	Default Value	Env. Override
jvm.default.version	Java Version installed and provided by this package	21	JVM_DEFAULT_VERSION

Java Commands Reference¶

java.defaultRunEnv¶

java.defaultRunEnv ?args?

Parameters¶

Description¶

java.docker¶

java.docker module imageSpec ?args?

Parameters¶


`module`	Not documented.
`imageSpec`	Not documented.

java.jar¶

java.jar module jarPath ?args?

Parameters¶


`module`	Not documented.
`jarPath`	Not documented.

java.run¶

Runs java cmd line tool using jvm.default.version variable

java.run ?args?

Parameters¶

java.selected.bashEnv¶

Prints the env in bash format for the selected java

java.selected.bashEnv ?args?

Parameters¶


`args`	add --version VERSION to select a specific version.

java.selected.env¶

Returns env update required for the selected java

java.selected.env ?args?

Parameters¶

Return value¶

Returns env update required for the selected java

java.selected.run¶

java.selected.run tool ?args?

Parameters¶


`tool`	Not documented.