Core Java

Managing multiple Java installations

With more and more Java releases coming up, it’ll be more interesting to manage multiple Java installations on your local environment. Different projects may require different Java versions.

The jenv project is a convenient way how to manage Java installations. It can setup local Java installations on global, directory and shell level and uses easy-to-remember Java version identifiers:

$> jenv versions

# switch to JDK 13 globally
$> jenv global 13.0

# switch to JDK 9 locally
$> cd project/
$> jenv local 9.0

$> java -version
java version "9.0.4"
Java(TM) SE Runtime Environment (build 9.0.4+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.4+11, mixed mode)

$> cd .. && java -version
openjdk version "13.0.1" 2019-10-15
OpenJDK Runtime Environment AdoptOpenJDK (build 13.0.1+9)
Eclipse OpenJ9 VM AdoptOpenJDK (build openj9-0.17.0, ...)

Jenv stores the local Java version in a .java-version file.

Jenvs works by declaring wrapper java binaries that direct to the corresponding installation based on the context.

Shell scripts can also set a specific version via the JENV_VERSION environment variable:



# will use JDK 13
java -version

Some of the content of this post was reposted from my newsletter issue 025.

Published on Java Code Geeks with permission by Sebastian Daschner, partner at our JCG program. See the original article here: Code Ready Containers – Getting Started with HR Employee Rewards Project in the Cloud

Opinions expressed by Java Code Geeks contributors are their own.

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Sebastian Daschner

Sebastian Daschner is a self-employed Java consultant and trainer. He is the author of the book 'Architecting Modern Java EE Applications'. Sebastian is a Java Champion, Oracle Developer Champion and JavaOne Rockstar.
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Asus Touchpad
2 years ago

I’m Elena gillbert.jEnv is a command line tool to help you forget how to set the JAVA_HOME environment variable. So, while it doesn’t install different versions of Java, jEnv makes it much easier to manage the versions already on your machine (like those installed by jabba). Just a note that, unfortunately for Windows users, it is not currently cross-platform.

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