JDTLS not working right

[sabinpocris]

Hi,
If I am into a Maven project, I get "file is a non-project file, only syntax errors are reported" .

However, if I change the -data parameter I get "class cannot be resolved to a type", even though the class's implementation is in the same folder.

Googling I saw another issue like this, maybe using (java-mode . ("jdtls" "-data" ".jdtls-cache")) is not the right choice?

What can I do?

I'm using the last jdtls snapshot, last eglot version and openjdk 18.

[joaotavora]

What can I do?

Ask the jdtls folks, maybe

[rrudakov]

Is your project a part of Git repository? As far as I understand eglot uses project.el to identify a project, so if you don't have a repository your class will be opened as a single file (not as a project).

[manuel-uberti]

Can you try using this snippet?

(with-eval-after-load 'eglot
  (let ((cache
         (expand-file-name (md5 (project-root (eglot--current-project)))
                           (locate-user-emacs-file
                            "eglot-eclipse-jdt-cache"))))
    (add-to-list 'eglot-server-programs
                 `(java-mode "jdtls" "-data" ,cache))))

[manuel-uberti]

I see. I think Eglot should stop guessing the work to be done with -data, then, because it seems like with -data either within or outside the Java project directory we are ending up with problems. As you said, if it's a regression in jdtls, we might be chasing things that are outside the scope of Eglot.

[sabinpocris]

Using this snippet and then creating a git repository fixed this for me (works with jdtls 1.15.0 and 1.9).
Removing this snippet I'm getting ".java is a non-project file, only syntax errors are reported".

[joaotavora]

You tried two things at once: which one fixed it? What about just creating a git repository?

[manuel-uberti]

Yes, that's what Eglot was doing before using a .jdtls-cache directory within the Java project directory. However, I still think it should not be up to Eglot to guess what jdtls wants to do with this -data thing.

[sabinpocris]

You tried two things at once: which one fixed it? What about just creating a git repository?

My bad.
Well, without the snippet, I'm getting that non-project file message.
If I'm into a simple folder with a few java files, the snippet fixes the problem.
However, in the Maven/Gradle project besides the snippet I also need to create a git repo in order for it to work.