# -*- mode: doom-docs-org -*-
#+title:    :lang java
#+subtitle: The poster child for carpal tunnel syndrome
#+created:  January 16, 2017
#+since:    1.3

* Description :unfold:
This module adds [[https://www.java.com][Java]] support to Doom Emacs, including ~android-mode~ and
~groovy-mode~.

** Maintainers
/This module has no dedicated maintainers./ [[doom-contrib-maintainer:][Become a maintainer?]]

** Module flags
- +lsp ::
  Enable LSP support for ~java-mode~. Requires [[doom-module:][:tools lsp]] and a langserver
  (supports eclipse.jdt.ls). *Incompatible with [[doom-module:][+meghanada]].*
- +meghanada ::
  Enable [[doom-package:][meghanada-mode]]. *Incompatible with [[doom-module:][+lsp]].*
- +tree-sitter ::
  Leverages tree-sitter for better syntax highlighting and structural text
  editing. Requires [[doom-module:][:tools tree-sitter]].

** Packages
- [[doom-package:][android-mode]]
- [[doom-package:][groovy-mode]]
- [[doom-package:][meghanada]] if [[doom-module:][+meghanada]]
- if [[doom-module:][+eclim]]
  - [[doom-package:][eclim]]
  - [[doom-package:][company-emacs-eclim]] if [[doom-module:][:completion company]]
- if [[doom-module:][+lsp]] and not [[doom-module:][:tools lsp +eglot]]
  - [[doom-package:][lsp-java]]

** Hacks
/No hacks documented for this module./

** TODO Changelog
# This section will be machine generated. Don't edit it by hand.
/This module does not have a changelog yet./

* Installation
[[id:01cffea4-3329-45e2-a892-95a384ab2338][Enable this module in your ~doom!~ block.]]

This module requires:
- [[https://www.oracle.com/java/technologies/downloads/][Java SDK]]
- The LSP test runner requires [[doom-module:][:tools debugger +lsp]] (requires [[doom-package:][dap-mode]])

** OpenJDK 11
*** Ubuntu
#+begin-src sh
apt-get install openjdk-11-jdk-headless
#+end_src

*** Fedora
#+begin_src sh
dnf install java-11-openjdk
#+end_src

** Oracle JDK 11
*** Ubuntu
#+begin_src sh
add-apt-repository ppa:linuxuprising/java
apt update
apt install oracle-java11-installer
apt install oracle-java11-set-default
#+end_src

*** Fedora
#+begin_src sh
curl -O https://download.java.net/java/GA/jdk11/9/GPL/openjdk-11.0.2_linux-x64_bin.tar.gz
tar zxvf openjdk-11.0.2_linux-x64_bin.tar.gz
sudo mv jdk-11.0.2/ /usr/local/
#+end_src

Open =/etc/profile.d/jdk11.sh= as root and add:
#+begin_src sh
export JAVA_HOME=/usr/local/jdk-11.0.2
export PATH=$PATH:$JAVA_HOME/bin
#+end_src

Save the file and source it:
#+begin_src sh
source /etc/profile.d/jdk11.sh
java -version
#+end_src

** Multiple Java Versions
It is common to need support for multiple Java versions. You can use a generic
tool like [[https://github.com/shyiko/jabba][jabba]] to install and manage multiple Java versions on any OS.

To have a different version of Java per-project, it is recommended you use
[[https://github.com/direnv/direnv][direnv]] and [[doom-module:][:tools direnv]]; create a =.envrc= in the root of the project pointing
to the Java installation:
#+begin_src sh
PATH_add ~/.jabba/jdk/adopt@1.11.0-3
JAVA_HOME=~/.jabba/jdk/adopt@1.11.0-3
#+end_src

And then run ~$ direnv allow .~ in the project directory. The [[doom-module:][:tools direnv]]
module will automatically source this environment before activating LSP servers.

* TODO Usage
#+begin_quote
 🔨 /This module's usage documentation is incomplete./ [[doom-contrib-module:][Complete it?]]
#+end_quote

** [[doom-module:][+lsp]] features
According to [[https://github.com/emacs-lsp/lsp-java]], you get:
- As you type reporting of parsing and compilation errors (via [[doom-package:][flycheck]] or
  [[doom-package:][lsp-ui]])
- Code completion ([[doom-package:][company-lsp]] or complete-at-point)
- Javadoc hovers ([[doom-package:][lsp-ui]])
- Code actions ([[doom-package:][lsp-ui]])
- Code outline ([[doom-package:][imenu]])
- Code navigation ([[doom-package:][xref]])
- Code lens for references/implementations ([[doom-package:][xref]])
- Highlights
- Code formatting
- Maven pom.xml project support
- Limited Gradle support
- Visual debugger ([[doom-package:][dap-mode]])
- Test runner ([[doom-package:][dap-mode]])
- Project explorer integration ([[doom-package:][treemacs]])
- Integration with [[https://start.spring.io/][Spring Initializr]]

** =+meghanada= features
According to [[https://github.com/mopemope/meghanada-emacs/]], you get:
- Auto-update server module
- [[https://gradle.org/][Gradle]] and [[http://maven.apache.org/][Maven]] and Eclipse project support
- No need build tool's plugin
- Run build tool task
- Compile your project
- Syntax check and analyze java source ([[doom-package:][flycheck-meghanada]])
- Support =Generic Types=
- Code completion with [[doom-package:][company-mode]] ([[doom-package:][company-meghanada]])
- Optimize import and sort
- Jump declaration
- Run [[http://www.junit.org/][JUnit]] test (include test runner)
- Diagnostic reporting with [[doom-package:][flycheck]] ([[doom-package:][flycheck-meghanada]])
- Show symbol's type info with [[doom-package:][eldoc]]
- Search references
- Full-featured text search

* TODO Configuration
#+begin_quote
 🔨 /This module's configuration documentation is incomplete./ [[doom-contrib-module:][Complete it?]]
#+end_quote

** [[doom-module:][+lsp]]
Install the eclipse server by executing ~M-x lsp-install-server~ and selecting
=jdtls=. After that any newly opened =java= files should start the LSP server
automatically.

To update the server, perform ~SPC u M-x lsp-install-server~.

Note that if you change Java version you may need to remove the LSP server and
install it again. You can do this with ~M-x +lsp/uninstall-server~ followed by
~M-x lsp-install-server~.

Enable the [[doom-module:][:tools debugger +lsp]] module to get test runner support.

* Troubleshooting
/There are no known problems with this module./ [[doom-report:][Report one?]]

* Frequently asked questions
/This module has no FAQs yet./ [[doom-suggest-faq:][Ask one?]]

* TODO Appendix
#+begin_quote
 🔨 This module has no appendix yet. [[doom-contrib-module:][Write one?]]
#+end_quote