One option is to do C-u M-x cider-jack-in (that is, jack in with a universal argument). That allows you to edit the command line where you can put JAVA_HOME=/path/to/jdk in front, and that would set the JDK version.

Otherwise, you have to somehow set JAVA_HOME env variable in Emacs, there are a few guides on the internet how to do that, but none of them worked for me reliably. What I do is that I set the env in the terminal shell and then launch Emacs from there so that Emacs inherits the java version I want.

I think JAVA_HOME is set correctly, running terminal directly from emacs:

❯ echo $JAVA_HOME
/opt/homebrew/opt/openjdk

❯ java -version
openjdk version "22.0.1" 2024-04-16
OpenJDK Runtime Environment Homebrew (build 22.0.1)
OpenJDK 64-Bit Server VM Homebrew (build 22.0.1, mixed mode, sharing)

oh, no, it does actually work

/opt/homebrew/opt/openjdkWhat's inside that directory? It looks to me as the homebrew-installed Java does its own JDK selection under the hood.

just had to put it in front of the whole command :man-facepalming:

Yes, that's how env overriding works

yeah, stupid moment from my side 😅 though I still don't understand why the correct JAVA_HOME is not inherited... :thinking_face:

I think it is correct, but there is one additional layer of indirection (that relies on I don't know what) that causes the thing in /opt/homebrew/opt/openjdk to select a different JDK

What does which java says inside Eshell? (vs terminal)

/usr/bin/java

/usr/bin/java -version

openjdk version "22.0.1" 2024-04-16

/usr/libexec/java_home -V

In either Eshell or terminal

Matching Java Virtual Machines (4):
    21.0.1 (arm64) " Inc." - "Amazon Corretto 21" /Users/akis/Library/Java/JavaVirtualMachines/corretto-21.0.1/Contents/Home
    21.0.1 (arm64) "Oracle Corporation" - "OpenJDK 21.0.1" /Users/akis/Library/Java/JavaVirtualMachines/openjdk-21.0.1/Contents/Home
    17.0.4.1 (arm64) "Eclipse Adoptium" - "OpenJDK 17.0.4.1" /Library/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home
    1.8.0_382 (x86_64) "Eclipse Temurin" - "Eclipse Temurin 8" /Users/akis/Library/Java/JavaVirtualMachines/temurin-1.8.0_382/Contents/Home

(no difference between eshell/terminal)

That's funny. This list has neither 22 nor 11 🙂

hah, true 😅 Seems like a start of a nice, deep, rabbit hole 😂 I can live with universal command though, that was really helpful! 🙇 I'm sure I messed up java installs long time ago on this machine, so probably that's what's causing the pain right now

Yeah, I'd start with picking one way of installing and managing JDKs, and then extend it to Emacs. Because right now it's hard to tell who's setting your JAVA_HOME and how it later translates to the exact JDK install path.

Some people have success with SDKMAN, I personally just download tarballs and extract them to /Library/Java/JavaVirtualMachines/. Then I have a shell function that allows me to quickly switch JAVA_HOME between them.

I'd start by a ps aux | grep cider and see the cider version(s) present in your classpath

(-> (System/getProperty "java.class.path") (clojure.string/split #":") (->> (filter #(clojure.string/includes? % "cider")))) from the repl should do it

Both very helpful ideas! Indeed, it appears cider-nrepl is not on the classpath. :thinking_face:

And it is on the classpath in the case of a new project (`lein new app foo`). So something with this project in particular.

Lein update-in can be a bit wonky Do you have other plugins in that project?

Ooooo, if I switch the new (foo) project to clojure 1.10.1 I start getting the warning.

Did the new cider start requiring clojure 1.11?

Nope https://docs.cider.mx/cider/about/compatibility.html#clojure Not immediately obvious to me why this would happen if you don't have Lein plugins around. @U06PNK4HG anything comes to mind?

Cool, I'm happy to make an issue on the cider repo as well if that would be helpful.

Yup - also confirmed: changing the clojure dep to 1.11.3 in the real project also gets rid of the warning (and print starts working again as well)

> Cool, I'm happy to make an issue on the cider repo as well if that would be helpful. That would be welcome. Before that, you can try /home/harold/bin/lein update-in :dependencies conj \[nrepl/nrepl\ \"1.2.0-beta2\"\] -- update-in :plugins conj \[cider/cider-nrepl\ \"0.49.0\"\] -- repl :headless :host localhost (i.e. the same command emitted by CIDER) from the CLI. Does cider-nrepl disappear from the classpath too in that case? Also, are you on Lein latest? It has had more changes than usual in the last year or so I think.

$ lein --version
Leiningen 2.10.0 on Java 11.0.22 OpenJDK 64-Bit Server VM

Ah!

$ /home/harold/bin/lein update-in :dependencies conj \[nrepl/nrepl\ \"1.2.0-beta2\"\] -- update-in :plugins conj \[cider/cider-nrepl\ \"0.49.0\"\] -- repl :headless :host localhost
Warning: cider-nrepl requires Clojure 1.10.3 or greater.
Warning: cider-nrepl will not be included in your project.

https://codeberg.org/leiningen/leiningen/releases/tag/2.11.2 is latest, probably it includes a more recent Clojure by default and solves the issue

Yes, this project I'm working on explicitly pulls in 1.10.1

Thanks so much for your help @U45T93RA6 and @U11BV7MTK, I learned a lot. 🙇

Cheers. Normally I start cider-nrepl from the CLI as it is more debuggable. And it persists in case Emacs crashed/froze

That's a neat idea, makes sense that there are some tradeoffs for the convenience of letting cider-jack-in do it.

@U11BV7MTK @U0F7WES86 BTW, you can also press , in the REPL and select classpath.

I forgot about the lovely menu behind comma. Good call out

I just randomly bumped into this same issue when debugging why some old project (using clojure 1.10.0) had trouble running tests with cider

This issue has been fixed in master, need a release of cider-nrepl now. https://github.com/clojure-emacs/cider-nrepl/pull/883