Configuring eglot with Eclipse jdtls

[hjudt]

With recent master, I was able to configure eglot to use jdtls, since this newest incarnation (version 1.6?) sports a nice startup script - which is still a bit weird to use btw. Until now, I've always used lsp-mode and lsp-java for it because that worked somehow with lots of features. But I want to get rid of this and find eglot less intrusive.

Now, while some parts work - rudimentary formatting via eglot-format-buffer, I couldn't figure out how to make it use my custom code-format.xml. Here is my config:

(use-package eglot
  :bind (:map eglot-mode-map
              ("C-c <tab>" . company-complete)
              ("C-c e f n" . flymake-goto-next-error)
              ("C-c e f p" . flymake-goto-prev-error)
              ("C-c e r" . eglot-rename)
              ("C-c e f r" . eglot-format)
              ("C-c e f b" . eglot-format-buffer)
              ("C-c e a" . eglot-code-actions))
  :hook
  ((python-mode . eglot-ensure)
   (c-mode . eglot-ensure)
   (c++-mode . eglot-ensure)
   (java-mode . eglot-ensure))
  :config
  (setcdr (assq 'java-mode eglot-server-programs)
          `("jdtls" "-data" "/home/user/.cache/emacs/workspace/"
            "-javaagent:/home/user/work/src/lombok.jar"
            "-Xbootclasspath/a:/home/user/work/src/lombok.jar"
            "--jvm-arg=-XX:+UseG1GC"
            "--jvm-arg=-XX:+UseStringDeduplication"
            "-Djava.format.settings.url=file:///home/user/code-format.xml"
            "-Djava.format.settings.profile=myown"))
  :custom
  ((eglot-autoshutdown t)))

However, it seems the server doesn't respect the code-format.xml and uses some default settings. I cannot see any error messages about the code-format.xml in any logs.

Now I wonder, can I tell the server my settings using some other way? E.g. by using eglot-workspace-configuration? How would I do this? Has anyone here done this or can see what I did wrong in my configuration? I've thought about something like the following, though probably this is not correct:

  (add-hook 'java-mode-hook
            (lambda ()
              (setq-local eglot-workspace-configuration
                          '((:java . ("org.eclipse.jdt.core.formatter.lineSplit"
                                      "40"))))))

The goal is to set the line split to 40 just to see if it works when executing eglot-format-buffer.

[zsxh]

check eglot-initialization-options.

for example:

(defvar +eglot/initialization-options-map (make-hash-table :size 5))

(cl-defmethod eglot-initialization-options ((server eglot-lsp-server))
    (if-let ((init-options (gethash (eglot--major-mode server) +eglot/initialization-options-map)))
        init-options
      eglot--{}))

(add-to-list 'eglot-server-programs
               `(java-mode "jdtls"
                           "-configuration" ,(expand-file-name "cache/language-server/java/jdtls/config_linux" user-emacs-directory)
                           "-data" ,(expand-file-name "cache/java-workspace" user-emacs-directory)
                           ,(concat "--jvm-arg=-javaagent:" (expand-file-name "~/.m2/repository/org/projectlombok/lombok/1.18.20/lombok-1.18.20.jar"))))

(puthash 'java-mode
           `(:settings
             (:java
              (:configuration
               (:runtime [(:name "JavaSE-1.8" :path "/usr/local/jdk-8")
                          (:name "JavaSE-11" :path "/usr/local/graalvm-ce-java11-22.0.0.2")
                          (:name "JavaSE-17" :path "/usr/local/graalvm-ce-java17-22.0.0.2" :default t)])
               :format (:settings (:url ,(expand-file-name (locate-user-emacs-file "cache/eclipse-java-google-style.xml"))
                                        :profile "GoogleStyle"))
               ;; NOTE: https://github.com/redhat-developer/vscode-java/issues/406#issuecomment-356303715
               ;; > We enabled it by default so that workspace-wide errors can be reported (eg. removing a public method in one class would cause compilation errors in other files consuming that method).
               ;; for large workspaces, it may make sense to be able to disable autobuild if it negatively impacts performance.
               :autobuild (:enabled t)
               ;; https://github.com/dgileadi/vscode-java-decompiler
               :contentProvider (:preferred "fernflower")))
             ;; WIP: support non standard LSP `java/classFileContents', `Location' items that have a `jdt://...' uri
             ;; https://github.com/eclipse/eclipse.jdt.ls/issues/1384
             ;; nvim impl demo: https://github.com/mfussenegger/dotfiles/commit/3cddf73cd43120da2655e2df6d79bdfd06697f0e
             ;; lsp-java impl demo: https://github.com/emacs-lsp/lsp-java/blob/master/lsp-java.el
             :extendedClientCapabilities (:classFileContentsSupport t)
             ;; bundles: decompilers, etc.
             ;; https://github.com/dgileadi/dg.jdt.ls.decompiler
             :bundles ,(let ((bundles-dir (expand-file-name (locate-user-emacs-file "cache/language-server/java/bundles" user-emacs-directory)))
                             jdtls-bundles)
                         (->> (when (file-directory-p bundles-dir)
                                (directory-files bundles-dir t "\\.jar$"))
                              (append jdtls-bundles)
                              (apply #'vector))))
           +eglot/initialization-options-map)

PS: I am also switching from lsp-mode to elgot and eglot gives me a feeling that it is much faster than lsp-mode (only tested in java).
WARN: jdtls has serveral non standard LSPs that eglot does not support, such as Location items jdt://..., extendedClientCapabilities java/classFileContents, etc.

[theothornhill]

Apologies for reviving an old thread, @zsxh. Can you goto definition to library methods etc using eglot with the fernflower decompiler? I cannot get that to work, no matter how hard i try. I only get an empty list when using M-.. Did you do anything in particular to support this?

[dalanicolai]

From point 3 here, shouldn't the data directory be different per project?

e.g. as follows

(add-to-list 'eglot-server-programs 
	     '(java-mode . (lambda (i p)
			     (list "/home/dalanicolai/opt/jdt-language-server-1.30.1-202312071447/bin/jdtls"
				   "-configuration" "/home/dalanicolai/.cache/jdtls"
				   "-data" (concat (project-root p) "jdtls-data")))))

[hjudt]

Thanks a lot! This helped me getting my setup working.

What still does not work, however, is organizing imports. I get

[client-request] (id:6) Fri Mar 18 10:59:51 2022:
(:jsonrpc "2.0" :id 6 :method "workspace/executeCommand" :params
          (:command "java.apply.workspaceEdit" :arguments
                    [(:changes
                      (:file:///home/user/tmp/hello-world/HelloWorld\.java
                       [(:range
                         (:start
                          (:line 0 :character 0)
                          :end
                          (:line 4 :character 0))
                         :newText "")]))]))
[server-reply] (id:6) ERROR Fri Mar 18 10:59:51 2022:
(:jsonrpc "2.0" :id 6 :error
          (:code -32601 :message "No delegateCommandHandler for java.apply.workspaceEdit"))

But I guess this is a language server bug/incompatibility (perhaps eclipse-jdtls/eclipse.jdt.ls#376)? Or does the "organize imports" code action work for you?

[joaotavora]

Yes, this is a language server bug/incompatibility. See this annoucemen: #868

You can still usethe simple jtdls script, but to recover this, you must re-create some of the previous configuration so that can work around it:

(cl-defmethod eglot-execute-command
    (_server (_cmd (eql java.apply.workspaceEdit)) arguments)
    "Eclipse JDT breaks spec and replies with edits as arguments."
    (mapc #'eglot--apply-workspace-edit arguments)))

Let me know if this works.

[hjudt]

It makes a difference, but instead of organizing the imports, it now seems to remove them.

[hjudt]

[client-request] (id:11) Fri Mar 18 12:11:26 2022:
(:jsonrpc "2.0" :id 11 :method "textDocument/codeAction" :params
          (:textDocument
           (:uri "file:///home/user/tmp/hello-world/HelloWorld.java")
           :range
           (:start
            (:line 0 :character 0)
            :end
            (:line 2 :character 0))
           :context
           (:diagnostics
            [])))
[server-request] (id:2) Fri Mar 18 12:11:26 2022:
(:jsonrpc "2.0" :id "2" :method "workspace/configuration" :params
          (:items
           [(:scopeUri "file:///home/user/tmp/hello-world/HelloWorld.java" :section "java.format.tabSize")
            (:scopeUri "file:///home/user/tmp/hello-world/HelloWorld.java" :section "java.format.insertSpaces")]))
[client-reply] (id:2) Fri Mar 18 12:11:26 2022:
(:jsonrpc "2.0" :id "2" :result
          [nil nil])
[server-reply] (id:11) Fri Mar 18 12:11:26 2022:
(:jsonrpc "2.0" :id 11 :result
          [(:title "Organize imports" :command "java.apply.workspaceEdit" :arguments
                   [(:changes
                     (:file:///home/user/tmp/hello-world/HelloWorld\.java
                      [(:range
                        (:start
                         (:line 0 :character 0)
                         :end
                         (:line 3 :character 0))
                        :newText "")]))])
           (:title "Organize imports" :kind "source.organizeImports" :diagnostics
                   []
                   :command
                   (:title "Organize imports" :command "java.apply.workspaceEdit" :arguments
                           [(:changes
                             (:file:///home/user/tmp/hello-world/HelloWorld\.java
                              [(:range
                                (:start
                                 (:line 0 :character 0)
                                 :end
                                 (:line 3 :character 0))
                                :newText "")]))]))
           (:title "Generate toString()" :kind "source.generate.toString" :diagnostics
                   []
                   :command
                   (:title "Generate toString()" :command "java.apply.workspaceEdit" :arguments
                           [(:changes
                             (:file:///home/user/tmp/hello-world/HelloWorld\.java
                              [(:range
                                (:start
                                 (:line 5 :character 4)
                                 :end
                                 (:line 5 :character 4))
                                :newText "@Override\n	public String toString() {\n		return \"HelloWorld []\";\n	}\n\n	")]))]))
           (:title "Change modifiers to final where possible" :kind "source.generate.finalModifiers" :diagnostics
                   []
                   :command
                   (:title "Change modifiers to final where possible" :command "java.apply.workspaceEdit" :arguments
                           [(:changes
                             (:file:///home/user/tmp/hello-world/HelloWorld\.java
                              [(:range
                                (:start
                                 (:line 5 :character 28)
                                 :end
                                 (:line 57 :character 29))
                                :newText "final String[] args) {\n        System.out.println(\"Hello, World, this is a very very very long line!\");\n        System.out.println(\"Test\");\n\n        final int month = 0;\n        String monthString = \"\";\n        final Byte b = 0;\n        final Character c = 'c';\n        switch (month) {\n            case 1:\n                monthString = \"Januaryyyyyyyyyyyyyyyyyyyyyyyyyyyy yyyy\";\n                break;\n            case 2:\n                monthString = \"February\";\n                break;\n            case 3:\n                monthString = \"March\";\n                break;\n            case 4:\n                monthString = \"April\";\n                break;\n            case 5:\n                monthString = \"May\";\n                break;\n            case 6:\n                monthString = \"June\";\n                break;\n            case 7:\n                monthString = \"July\";\n                break;\n            case 8:\n                monthString = \"August\";\n                break;\n            case 9:\n                monthString = \"September\";\n                break;\n            case 10:\n                monthString = \"October\";\n                break;\n            case 11:\n                monthString = \"November\";\n                break;\n            case 12:\n                monthString = \"December\";\n                break;\n            default:\n                monthString = \"Invalid month\";\n                break;\n        }\n        System.out.println(monthString);\n    }\n\n    public static void main2(final ")]))]))])
[internal] (id:12) Fri Mar 18 12:11:34 2022:
(:deferring :textDocument/signatureHelp :id 12 :params
            (:textDocument
             (:uri "file:///home/user/tmp/hello-world/HelloWorld.java")
             :position
             (:line 0 :character 0)))

[joaotavora]

Seems to be a server bug? This is what the server returned for "organizeImports" 🤷 . Notice the newText "" Maybe removing them is the correct way to organize them in your HelloWorld.java program?

       (:title "Organize imports" :kind "source.organizeImports" :diagnostics
                   []
                   :command
                   (:title "Organize imports" :command "java.apply.workspaceEdit" :arguments
                           [(:changes
                             (:file:///home/user/tmp/hello-world/HelloWorld\.java
                              [(:range
                                (:start
                                 (:line 0 :character 0)
                                 :end
                                 (:line 3 :character 0))
                                :newText "")]))]))

[hjudt]

Hm. Maybe. I've downloaded the latest version of the jdtls.
I've even tried to use the imported stuff correctly so no other diagnostics get triggered (all warnings fixed), and also executed eglot-code-action-organize-imports directly, but to no avail.

[hjudt]

On the other hand, these imports just don't seem to be necessary, so you might be correct. I'd thought one had to use action remove imports for removing unneeded imports, but apparently not.

[hjudt]

I'll try with a better example.

[hjudt]

Yes, it seems to remove (only) the unused imports. So it actually works correctly. Thanks.