![[macOS] Manage Java versions by jEnv](/assets/images/category/environment/2020/nvm/background.avif)
Contents
Outline
When developing multiple Java projects on a single machine (PC), there are cases where you need to build a development environment depending on the Java version used in each project.
In this case, you cannot delete Java and install the Java version required for the project each time. In this blog post, I will introduce how to use jEnv to install and manage various Java versions on a single machine in macOS.
Install jEnv
Execute the following command to install jEnv.
brew install jenv
Then, run the following command to activate the export plugin and the maven plugin.
jenv enable-plugin export
jenv enable-plugin maven
Also, run the following command to use the Java version managed by jEnv.
echo 'export alias java=$HOME/.jenv/shims/java' >> ~/.zshrc`
Java version list
Run the following command to check the Java versions that can be installed.
brew search openjdk
Then, you can see the list of installable Java versions as follows.
==> Formulae
openjdk ✔ openjdk@11 ✔ openjdk@17 ✔ openjdk@8 openj9 openvdb
==> Casks
adoptopenjdk adoptopenjdk/openjdk/adoptopenjdk14
adoptopenjdk/openjdk/adoptopenjdk-jre adoptopenjdk/openjdk/adoptopenjdk14-jre
...
Install OpenJDK
In this blog post, I will install 11 and 17 versions of OpenJDK. Run the following command to install the OpenJDK 11 version.
brew install openjdk@11
After the installation is complete, use the following command to register the installed JDK to jEnv.
sudo ln -sfn /usr/local/opt/openjdk@11/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk-11.jdk
echo 'export PATH="/usr/local/opt/openjdk@11/bin:$PATH"' >> ~/.zshrc
export CPPFLAGS="-I/usr/local/opt/openjdk@11/include"
jenv add /usr/local/Cellar/openjdk@11/11.0.19/libexec/openjdk.jdk/Contents/Home
Then, install the OpenJDK 17 version in the same way and register it to jEnv.
brew install openjdk@17
sudo ln -sfn /usr/local/opt/openjdk@17/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk-17.jdk
echo 'export PATH="/usr/local/opt/openjdk@17/bin:$PATH"' >> ~/.zshrc
export CPPFLAGS="-I/usr/local/opt/openjdk@17/include"
jenv add /usr/local/Cellar/openjdk@17/17.0.7/libexec/openjdk.jdk/Contents/Home
jenv add /usr/local/Cellar/openjdk/20.0.1/libexec/openjdk.jdk/Contents/Home
jenv versions
After installing the Java versions, run the following command to check the available Java versions.
jenv versions
Then, you can see the OpenJDK 11 and OpenJDK 17 that you just installed as follows.
* system (set by JENV_VERSION environment variable)
11.0
11.0.19
openjdk64-11.0.19
openjdk64-17.0.7
jenv version
Run the following command to check the current Java version set by jEnv.
jenv version
Then, you can see the current Java version selected by jEnv as follows.
system (set by JENV_VERSION environment variable)
To check the actual Java version, run the following command.
java --version
Then, you can see the actual Java version as follows.
openjdk 20.0.1 2023-04-18
OpenJDK Runtime Environment Homebrew (build 20.0.1)
OpenJDK 64-Bit Server VM Homebrew (build 20.0.1, mixed mode, sharing)
Use installed Java version
Now, let’s see how to change the Java version using jEnv. If you run the following command, you can use OpenJDK 17 globally.
jenv global openjdk64-17.0.7
If you run the following command, you can use OpenJDK 17 only in the current project.
jenv local openjdk64-17.0.7
This command creates a .java-version file and, if jEnv is enabled in the development environment, jEnv automatically changes to use the version.
If you run the following command, you can use OpenJDK 17 only in the current shell.
jenv shell openjdk64-17.0.7
.java-version file
As mentioned earlier, if you run the jenv local command, you can see that the .java-version file is automatically created. This automatically changes the version of Java in the development environment using jEnv.
Therefore, if you use this .java-version file, you can share the Java version required to run the project. If the .java-version file of the current project does not exist, create the .java-version file and write the Java version required for the project as follows.
openjdk64-17.0.7
Completed
Done! We’ve seen how to use jEnv to use various Java versions on the same machine. If you need a development environment for various Java versions, try using jEnv to manage the versions.
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