Inside IntelliJ versus outside IntelliJ

• For running a project from within IntelliJ, you specify which JDK to use by configuring within IntelliJ.
• The current default JDK set by SDKMAN! only applies to Java apps being executed on their own, outside IntelliJ.

Unfortunately, configuring which JDK to run your app within IntelliJ is complicated and confusing, requiring you to go spelunking through various buried panels.

These panels include some for the JDK, and some for the language level (which version of Java to target):

• File | Project Structure | Project Settings | Project | SDK … and Language Level.
• File | Project Structure | Project Settings | Project | Modules | Language Level.
• Settings | Build, Execution, Deployment | Compiler | Java Compiler | Per-module bytecode version.

There may be others I don't recall at the moment. Search Stack Overflow to learn more.

If you are building a Web app in IntelliJ Ultimate edition, and running that app from within IntelliJ via an external application server such as Tomcat, Jetty, Glassfish, OpenLiberty, etc., then you need to also specify in another IntelliJ panel which JDK should be used to launch that app server.

If using Maven or Gradle, you need to specify language level there too.

I use jenv to switch between different java versions on mac.

>brew info jenv
==> jenv: stable 0.5.6 (bottled), HEAD
Manage your Java environment
https://www.jenv.be/
/opt/homebrew/Cellar/jenv/0.5.6 (86 files, 78KB) *
  Poured from bottle on 2023-02-15 at 07:31:25
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/jenv.rb
License: MIT
==> Options
--HEAD
    Install HEAD version
==> Caveats
To activate jenv, add the following to your shell profile e.g. ~/.profile
or ~/.zshrc:
  export PATH="$HOME/.jenv/bin:$PATH"
  eval "$(jenv init -)"

With

jenv local 11.0

or

jenv local 17.0

for example, I can switch do different versions of installed java.

For me, the problem was the ending of .bashrc. I know, it explicitly says there "THIS MUST BE AT THE END OF THE FILE FOR SDKMAN TO WORK!!!", but I still decided to ignore that and wrote a few of my own lines after those ones 🤡. When I made sure the sdkman's lines were indeed at the very end of the file and after running sdk selfupdate force, setting the version started working properly across different terminals.

This answer is an attempt to address: how to control java version system-wide (not just in currently running shell) when several versions of JDK are installed for development purposes on macOS El Capitan or newer (Sierra, High Sierra, Mojave). As far as I can tell, none of the current answers do that (*).

As a developer, I use several JDKs, and I want to switch from one to the other easily. Usually I have the latest stable one for general use, and others for tests. But I don't want the system (e.g. when I start my IDE) to use the latest "early access" version I have for now. I want to control system's default, and that should be latest stable.

The following approach works with Java 7 to 12 at least (early access at the time of this writing), with Oracle JDK or OpenJDK (including builds by AdoptOpenJDK produced after mid-October 2018).

Solution without 3rd party tools:

• leave all JDKs at their default location, under /Library/Java/JavaVirtualMachines. The system will pick the highest version by default.
• To exclude a JDK from being picked by default, rename its Contents/Info.plist to Info.plist.disabled. That JDK can still be used when $JAVA_HOME points to it, or explicitly referenced in a script or configuration. It will simply be ignored by system's java command.

System launcher will use the JDK with highest version among those that have an Info.plist file.

When working in a shell with alternate JDK, pick your method among existing answers (jenv, or custom aliases/scripts around /usr/libexec/java_home, etc).

Details of investigation in this gist.

(*) Current answers are either obsolete (no longer valid for macOS El Capitan or Sierra), or only address a single JDK, or do not address the system-wide aspect. Many explain how to change $JAVA_HOME, but this only affects the current shell and what is launched from there. It won't affect an application started from OS launcher (unless you change the right file and logout/login, which is tedious). Same for jenv, it's cool and all, but as far as I can tell it merely changes environment variables, so it has the same limitation.