Re: java anyone?

[Pankaj Jangid]

Jean-Christophe Helary <lists@traduction-libre.org> writes:

> I need something where I can just lookup functions in a code base with
> a local javadoc tree, including online Oracle documentation, etc. Not
> a full-fledged IDE with completion.

I use a very lightweight language server facilitator, named Eglot. There
are a couple of settings that are required for this to work. This is the
minimal set that I came-up with after discussing in and following the
Eglot tracker.

1. Tell Emacs the value of JAVA_HOME. ‘(setenv "JAVA_HOME" ...)’

2. By default, Eglot uses, Eclipse JDT Language server so you need to
   install it somewhere. I simply pulled the git repository at
   ~/.emacs.d/eclipse.jdt.ls. After building the Eclipse JDT LS (‘mvn
   clean; mvn package’), you must add the language server JAR to the
   CLASSPATH. I use the following snippet:

--8<---------------cut here---------------start------------->8---
   (defun add-to-classpath (item)
     "Add ITEM to CLASSPATH."
     
     (let ((class-path (getenv "CLASSPATH")))
       
       (defvar class-path-list (if class-path
                                   (split-string class-path ":")))
       (cl-pushnew item class-path-list)
       (setenv "CLASSPATH"
               (mapconcat 'identity class-path-list ":"))))

   (add-to-classpath
    (substring
     (shell-command-to-string
      (format
       "find %s -name 'org.eclipse.equinox.launcher_*jar'"
       (expand-file-name
        "eclipse.jdt.ls/org.eclipse.jdt.ls.product/target/repository/plugins"
        user-emacs-directory)))
     0 -1))
--8<---------------cut here---------------end--------------->8---

Eglot works with project.el, xref.el, eldoc.el etc. So many usual things
will work out of the box. Like online help when the point is inside a
function name. 

It also works with company; but that is not required.