Java layer

img/java.png

Description

This layer adds support for the Java language.

Features:

Support for the following backends:
- Meghanada client/server (default),
- Eclim client/server,
- ENSIME client/server.
Each provides:
- Auto-completion using company
- Linting using flycheck integration
- Maven and Gradle integration

Layer Installation

Layer

To use this configuration layer, add it to your ~/.spacemacs. You will need to add java to the existing dotspacemacs-configuration-layers list in this file.

Choosing a backend

To choose a default backend set the layer variable java-backend:

(java :variables java-backend 'eclim)

Backend can be chosen on a per project basis using directory local variables (files named .dir-locals.el at the root of a project), an example to use the eclim backend:

;;; Directory Local Variables
;;; For more information see (info "(emacs) Directory Variables")

((java-mode (java-backend . eclim)))

Note: you can easily add a directory local variable with SPC f v d.

If you want to use the Ensime backend, you should modify your ~/.spacemacs to use the recommended Ensime version (Stable). Please add the following lines to dotspacemacs/user-init:

  (push '("melpa-stable" . "stable.melpa.org/packages/") configuration-layer-elpa-archives)
  (push '(ensime . "melpa-stable") package-pinned-packages)

Backends

Meghanada

Meghanada is composed of a lightweight server and an Emacs minor mode. It is unintrusive and integrates with company and flycheck.

Both Gradle and Maven projects are compatible with Meghanada.

Meghanada is the default backend used by this layer, see Choosing a backend in order to lean how to select a different backend.

Installation

The Meghanada server will be installed automatically whenever a Java file is opened.

If you get issues with the auto-installation you can either download the last version of the server manually there or build from source hosted on the GitHub repository and copy the jar file to .emacs.d/.cache/meghanada folder.

No additional configuration is necessary!

About Maven

Maven is not fully supported by Meghanada (but should still work fine for most projects). If you encounter disconnection from the server then run mvn install at the root of your project first.

Eclim

Eclim provides the ability to access Eclipse features such as code completion, searching, code validation, and many more.

Installation

Eclipse

First you need the last version of Eclispe from the official Eclipse site.

Note: if you are on MacOS there some issues between the new native Eclipse application installed by the Eclispe-install.app wizard and the Eclim installer wizard. The recommended way to install Eclipse on MacOS is by using homebrew or by get the tar.gz compressed file instead. With homebrew the command line to install Eclipse is brew cask install eclipse-jee.

Eclim

For installation of Eclim check the official page to download the installer then double click on it or launch it in the command line with the following command (the example is for MacOS, replace the eclispe.home definition by your correct location as well as the current version of eclim):

$ java -Dvim.skip=true -Declipse.home=/Applications/Eclipse.app/Contents/Eclipse -jar eclim_2.6.0.jar install

Configuration

You may need to set the Eclipse and Eclim paths in your dotfile as layer variables or in the dotspacemacs/user-config, for instance on MacOS as layer variables:

(java :variables java-backend 'eclim
                eclim-eclipse-dirs '("/Applications/Eclipse.app/Contents/Eclipse/")
                eclim-executable "/Applications/Eclipse.app/Contents/Eclipse/eclim")

You can also configure useful other options like the default location for the Eclim workspace (default value is ~/workspace), as shown below:

  (setq
   ;; Specify the workspace to use by default
   eclimd-default-workspace "/path/to/default/eclipse/workspace"
   ;; wether autostarting eclimd or not (default nil)
   eclimd-autostart t
   ;; Whether or not to block emacs until eclimd is ready (default nil)
   eclimd-wait-for-process t)

Usage

Start the eclim daemon with SPC m D s and stop it with SPC m D k. (See below.)

Syntax checking is performed only on demand with SPC e e to preserve perfomance.

Auto-save feature may freeze Emacs sometimes, use C-g to unfreeze Emacs or atlernatively you can set dotspacemacs-auto-save-file-location to nil.

ENSIME

Another backend option is the ENSIME server, which is a lot more responsive than Eclim. ENSIME is originally made to work with Scala but it now works with plain Java projects as well.

Installation when using SBT

Find it with your favourite package manager, eg:

  nix-env --install sbt

or refer to the sbt installation instructions.

Installation when using Gradle

Refer to the Ensime installation instructions to install the ensime-gradle plugin.

Configuration

Follow the ENSIME configuration instructions. Spacemacs uses the development version of Ensime so follow the appropriate steps.

To use the build functions under SPC m b you need to use version 0.13.5 or newer of sbt, and specify that in your project's project/build.properties. For example,

  sbt.version=0.13.11

Usage

SPC SPC spacemacs/ensime-gen-and-restart or SPC m D r generates a new config for a project and starts the server. Afterwards SPC SPC ensime or SPC m D s will suffice do the trick.

Issues

ENSIME is originally built for Scala, so support for java is not complete, in particular refactoring doesn't work.

Key bindings

Meghanada

Server

Key Binding	Description
`SPC m D c`	Connect to server
`SPC m D d`	Disconnect from server
`SPC m D i`	Install server (should be done automatically
`SPC m D k`	Kill server
`SPC m D l`	Clear server cache
`SPC m D p`	Ping server
`SPC m D r`	Restarrt server
`SPC m D s`	Start server
`SPC m D u`	Update server
`SPC m D v`	Print version of the server

Navigation

Key Binding	Description
`SPC m g b`	Jump back to previous location
`SPC m g g`	Jump to declaration

Compilation

Key Binding	Description
`SPC m c b`	Compile file (buffer)
`SPC m c c`	Compile project

Tests (junit)

Key Binding	Description
`SPC m t a`	Run all tests
`SPC m t c`	Run test class around point
`SPC m t l`	Run last tests
`SPC m t t`	Run test cause around point

Refactoring

Key Binding	Description
`SPC m =`	Beautify code
`SPC m r i`	Optimize imports
`SPC m r I`	Import all
`SPC m r n`	Create a new class, interface, or enum

Tasks

Key Binding	Description
`SPC m x :`	Run task

Eclim

Java-mode

Ant

Key Binding	Description
`SPC m a a`	Run Ant
`SPC m a c`	Clear Ant cache
`SPC m a r`	Run Ant
`SPC m a v`	Validate

Project management

Key Binding	Description
`SPC m p b`	Build project
`SPC m p c`	Create project
`SPC m p d`	Delete project
`SPC m p g`	Open file in current project
`SPC m p i`	Import project
`SPC m p j`	Information about project
`SPC m p k`	Close project
`SPC m p o`	Open project
`SPC m p p`	Open project management buffer
`SPC m p r`	Run project
`SPC m p u`	Update project

Eclim daemon

Key Binding	Description
`SPC m D k`	Kill daemon
`SPC m D s`	Start daemon

Goto

Key Binding	Description
`M-,`	jump back from go to declaration/definition
`SPC m g g`	go to declaration
`SPC m g t`	go to type definition

Refactoring

Key Binding	Description
`SPC m r c`	create a constructor
`SPC m r f`	format file
`SPC m r g`	generate getter and setter
`SPC m r i`	optimize imports
`SPC m r j`	implement or override a method
`SPC m r n`	create a new class, enum, or interface
`SPC m r r`	rename symbol

Documentation, Find

Key Binding	Description
`SPC m f f`	general find in project
`SPC m h c`	call hierarchy
`SPC m h h`	show documentation for symbol at point
`SPC m h i`	view hierarchy
`SPC m h u`	show usages for symbol at point

Errors (problems)

Key Binding	Description
`SPC e e`	Force an error check
`SPC e l`	List errors
`SPC e n`	Next error
`SPC e p`	Previous error
`SPC m e e`	Correct error around point

Tests

Key Binding	Description
`SPC m t t`	run JUnit tests for current method or current file or project

Errors (problems) buffer

Key Binding	Description
`RET`	go to problem place
`a`	show all problems
`e`	show only errors
`f`	show problems only for current file
`g`	refresh problems
`q`	quit
`w`	show only warnings

Projects buffer

Key Binding	Description
`RET`	go to current project
`c`	go to problem place
`D`	delete project
`g`	refresh buffer
`i`	info about current project
`I`	import existing project into the workspace
`m`	mark current project
`M`	mark all projects
`N`	create new project
`o`	open project
`p`	update project
`q`	quit
`R`	rename current project
`u`	unmark current project
`U`	unmark all projects

Ensime key bindings

Search

Key Binding	Description
`SPC m /`	incremental search using `ensime-scalex` major mode
`SPC m ?`	incremental search in all live buffers

Ensime Search Mode

Key Binding	Description
`C-j`	Move to next match
`C-k`	Move to previous match
`C-i`	Insert at point import of current result
`RET`	Jump to the target of the currently selected ensime-search-result
`C-q`	Quit ensime search

sbt

Key Binding	Description
`SPC m b .`	sbt transient state
`SPC m b b`	sbt command
`SPC m b c`	compile
`SPC m b C`	clean command
`SPC m b i`	switch to sbt shell
`SPC m b p`	package command
`SPC m b r`	run command

Typecheck

Key Binding	Description
`SPC m c t`	type check the current file
`SPC m c T`	type check all the open buffers

Debug

Key Binding	Description
`SPC m d A`	Attach to a remote debugger
`SPC m d b`	set breakpoint
`SPC m d B`	clear breakpoint
`SPC m d C`	clear all breakpoints
`SPC m d c`	continue
`SPC m d i`	inspect value at point
`SPC m d n`	next
`SPC m d o`	step out
`SPC m d q`	quit
`SPC m d r`	run
`SPC m d s`	step
`SPC m d t`	backtrace

Note: These key bindings need a transient-state, PR welcome :-)

Errors

Key Binding	Description
`SPC m e e`	print error at point
`SPC m e l`	show all errors and warnings
`SPC m e s`	switch to buffer containing the stack trace parser

Goto

Key Binding	Description
`SPC m g g`	go to definition
`SPC m g i`	go to implementation
`SPC m g t`	go to test

Print and yank types

`SPC m h T`	print full type name at point
`SPC m h t`	print short type name at point
`SPC m y T`	yank full type name at point
`SPC m y t`	yank short type name at point

Documentation, Inspect

Key Binding	Description
`SPC m h h`	show documentation for symbol at point
`SPC m h u`	show uses for symbol at point
`SPC m i i`	inspect type at point
`SPC m i I`	inspect type in other frame
`SPC m i p`	inspect project package

Server

Key Binding	Description
`SPC m D f`	reload open files
`SPC m D r`	regenerate the `.ensime` and restart the ensime server
`SPC m D s`	start ensime server

Refactoring

Key Binding	Description
`SPC m r a`	add type annotation
`SPC m r f`	format source
`SPC m r d`	get rid of an intermediate variable (`ensime-refactor-inline-local`)
`SPC m r D`	get rid of an intermediate variable (`ensime-undo-peek`)
`SPC m r i`	organize imports
`SPC m r m`	extract a range of code into a method
`SPC m r r`	rename a symbol project wide
`SPC m r t`	import type at point
`SPC m r v`	extract a range of code into a variable
`SPC m z`	expand/contract region

Tests

Key Binding	Description
`SPC m t a`	test command (sbt)
`SPC m t r`	test quick command (sbt)
`SPC m t t`	test only (sbt)

REPL

Key Binding	Description
`SPC m s a`	ask for a file to be loaded in the REPL
`SPC m s b`	send buffer to the REPL
`SPC m s B`	send buffer to the REPL and focus the REPL buffer in `insert state`
`SPC m s i`	start or switch to the REPL inferior process
`SPC m s r`	send region to the REPL
`SPC m s R`	send region to the REPL and focus the REPL buffer in `insert state`

Maven

Key Binding	Description
`SPC m m c c`	Compile
`SPC m m c C`	Clean
`SPC m m c r`	Clean and compile
`SPC m m g a`	Switch between class and test file
`SPC m m g A`	Switch between class and test file in another window
`SPC m m t a`	Run all tests
`SPC m m t C-a`	Clean and run all tests
`SPC m m t b`	Run current buffer tests
`SPC m m t i`	Test and install
`SPC m m t t`	Run a specific test

Gradle

Key Binding	Description
`SPC m l c c`	Compile
`SPC m l c C`	Clean
`SPC m l c r`	Clean and compile
`SPC m l t a`	Run all tests
`SPC m l t b`	Run current buffer tests
`SPC m l t t`	Run a specific test
`SPC m l x`	Execute a Gradle task

using-java-in-emacs.org

Java layer

Description

Features:

Layer Installation

Layer

Choosing a backend

Backends

Meghanada

Installation

About Maven

Eclim

Installation

Eclipse

Eclim

Configuration

Usage

ENSIME

Installation when using SBT

Installation when using Gradle

Configuration

Usage

Issues

Key bindings

Meghanada

Server

Navigation

Compilation

Tests (junit)

Refactoring

Tasks

Eclim

Java-mode

Ant

Project management

Eclim daemon

Goto

Refactoring

Documentation, Find

Errors (problems)

Tests

Errors (problems) buffer

Projects buffer

Ensime key bindings

Search

Ensime Search Mode

sbt

Typecheck

Debug

Errors

Goto

Print and yank types

Documentation, Inspect

Server

Refactoring

Tests

REPL

Maven

Gradle