/usr/libexec/java_home: This will show you where the current JDK home is, for example:
/usr/libexec/java_home -V: This lists all installed JDKs, which is shown below:
To switch between JDKs, use /usr/libexec/java_home -v version (e.g. 10):
Knowing that your available JDKs are installed to /Library/Java/JavaVirtualMachines/ by default, moving the contents of the downloaded OpenJDK 11 dir from inside the .gz file to the same location would make sense.
Once you’ve moved it there, java_home -V now shows the new JDK in place:
Updating my aliases to quickly switch versions in my .bash_profile, I now have:
Sourcing the .bash_profile (source .bash_profile) and then running each alias, now I’ve got OpenJDK 11 set up and ready to go!