Java And The JVM

3 minute read

Versions and setup


The following JDKs are installed:

  • OpenJDK 8

  • OpenJDK 11

  • OpenJDK 17

Oracle JDK 7, 8 and 9 were removed in Ubuntu Focal. Please switch to OpenJDK versions.

We provide the function jdk_switcher, available as a setup command, to choose the JDK for your builds. This function can take one of two commands, use or home:

  • use will select the given JDK by changing the Java executables, and setting JAVA_HOME and JRE_HOME.

  • home will print out the value of JAVA_HOME for a given JDK (but make no modifications).

The valid values for use or home are openjdk8, openjdk11 and openjdk17. By default, OpenJDK 11 is selected. The following is the resulting Java version, JAVA_HOME, and JRE_HOME for each JDK:

OpenJDK 8

jdk_switcher home openjdk8 # /usr/lib/jvm/java-8-openjdk-amd64 jdk_switcher use openjdk8 echo $JAVA_HOME # /usr/lib/jvm/java-8-openjdk-amd64 echo $JRE_HOME # /usr/lib/jvm/java-8-openjdk-amd64/jre java -version # openjdk version "1.8.0_402" # OpenJDK Runtime Environment (build 1.8.0_402-8u402-ga-2ubuntu1~20.04-b06) # OpenJDK 64-Bit Server VM (build 25.402-b06, mixed mode)

OpenJDK 11 (Default)

jdk_switcher home openjdk11 # /usr/lib/jvm/java-11-openjdk-amd64 jdk_switcher use openjdk11 echo $JAVA_HOME # /usr/lib/jvm/java-11-openjdk-amd64 echo $JRE_HOME # /usr/lib/jvm/java-11-openjdk-amd64/jre java -version # openjdk version "11.0.22" 2024-01-16 # OpenJDK Runtime Environment (build 11.0.22+7-post-Ubuntu-0ubuntu220.04.1) # OpenJDK 64-Bit Server VM (build 11.0.22+7-post-Ubuntu-0ubuntu220.04.1, mixed mode, sharing)

OpenJDK 17

jdk_switcher home openjdk17 # /usr/lib/jvm/java-17-openjdk-amd64 jdk_switcher use openjdk17 echo $JAVA_HOME # /usr/lib/jvm/java-17-openjdk-amd64 echo $JRE_HOME # /usr/lib/jvm/java-17-openjdk-amd64/jre java -version # openjdk version "17.0.10" 2024-01-16 # OpenJDK Runtime Environment (build 17.0.10+7-Ubuntu-120.04.1) # OpenJDK 64-Bit Server VM (build 17.0.10+7-Ubuntu-120.04.1, mixed mode, sharing)

Other Versions With SDKMAN

If you need to install a different JDK version, consider using SDKMAN to install it. For example if you want to install OpenJDK 20, you can add the following to your Setup Commands:

source /dev/stdin <<< "$(curl -sSL"

sdk install java 20-open

export PATH=$HOME/.sdkman/candidates/java/current/bin:$PATH

export JAVA_HOME=$HOME/.sdkman/candidates/java/current

# Add if you want to confirm the installed version
java -version

Note the available JDK versions in SDKMAN change as new JDK versions come out so the specific version you are installing may need to be updated occasionally. You can check the available versions by running sdk list java.

Build Tools

The following tools are preinstalled in our virtual machine. You can add them to your setup or test commands to start your build:

JVM-based languages

Scala, Clojure, Kotlin, Groovy and other JVM based languages should also run on CodeShip. Let us know if you find something that doesn’t work as expected.


Installing dependencies through Maven is fully supported.

Dependency Cache

CodeShip automatically caches the $HOME/.ivy2 and $HOME/.m2/repository directories between builds to optimize build performance. You can read this article to learn more about the dependency cache and how to clear it.

Frameworks And Testing

All build tools and test frameworks, such as JUnit, will work.

Parallel Testing

If you are running parallel test pipelines, you will want separate your tests into groups and call a group specifically in each pipeline. For instance:

Pipeline 1:

mvn test -Dtest=class_1

Pipeline 2:

mvn test -Dtest=class_2

Parallelization Modules

In addition to parallelizing your tests explicitly via parallel pipelines, some customers have found using the parallel features in JUnit and other testing frameworks to be a good way to speed up your tests.

Note that aggressive parallelization can cause resource and build failure issues, as well.

Notes And Known Issues

Due to Java version issues, you may find it helpful to test your commands with different versions via an SSH debug session if tests are running differently on CodeShip compared to your local machine.


The Java Cryptography Extension (JCE) ships from Oracle by default on Java 8 and Java 9. You can also check if JCE is in limited or unlimited mode by checking the allowed key length. Limited mode will return 128 and unlimited mode will return 2147483647.

jdk_switcher use oraclejdk9
jrunscript -e 'print (javax.crypto.Cipher.getMaxAllowedKeyLength("AES"));'