Install Homebrew:
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
Install jEnv using Homebrew:
brew install jenv
Add the cask-versions tap to Homebrew:
brew tap homebrew/cask-versions
Install Temurin 21 (formerly AdoptOpenJDK):
brew install --cask temurin21
Install other Java versions if necessary:
brew install --cask temurin8
Make these Java versions known to jEnv:
jenv add /Library/Java/JavaVirtualMachines/temurin-21.jdk/Contents/Home/
jenv add /Library/Java/JavaVirtualMachines/temurin-8.jdk/Contents/Home/
Use jEnv to set the global version of Java:
jenv global 21.0.1
Verify that jEnv is aware of these Java versions:
jenv versions
The output should look something like this:
system
1.8
1.8.0.392
21.0
21.0.1
temurin64-1.8.0.392
* temurin64-21.0.1 (set by /Users/<user>/.jenv/version)
The star (*) indicates that we have successfully set temurin64-21.0.1 globally.
We can set a local version of Java for the current working directory:
jenv local 1.8
This will create a file called .java-version which specifies the Java version to use for this directory.
We can check which version of Java is active:
java --version
The output should look something like this:
openjdk 21.0.1 2023-10-17 LTS
OpenJDK Runtime Environment Temurin-21.0.1+12 (build 21.0.1+12-LTS)
OpenJDK 64-Bit Server VM Temurin-21.0.1+12 (build 21.0.1+12-LTS, mixed mode)
Note that, for Java 8, we must use java -version (with one -):
java -version
See this Stack Overflow answer for more details.
SDKMAN is another viable alternative to jEnv.