Switching between multiple Java versions (macOS)

On macOS, java_home gives you the path for a given JDK version. Wire that into env vars and aliases and you can switch JVMs from the shell without touching system settings.

Drop this into your ~/.zshrc or ~/.bash_profile:

# Java
export JAVA8=`/usr/libexec/java_home -v 1.8`
export JAVA11=`/usr/libexec/java_home -v 11`
export JAVA17=`/usr/libexec/java_home -v 17`
export JAVA21=`/usr/libexec/java_home -v 21`

# default version of java
export JAVA_HOME=$JAVA21

# aliases for dynamic JVM switching
alias java8="export JAVA_HOME=\$JAVA8"
alias java11="export JAVA_HOME=\$JAVA11"
alias java17="export JAVA_HOME=\$JAVA17"
alias java21="export JAVA_HOME=\$JAVA21"

Usage: Open a new terminal (or source ~/.zshrc). Default is Java 21. Run java8, java11, java17, or java21 to switch for that session. java -version and any tool that reads JAVA_HOME will use the active one.

Only include the versions you actually have installed—java_home will error if the JDK isn’t there.