Use Vim as a Java IDE

why canonical_url do not word?!
the origin URL is https://spacevim.org/use-vim-as-a-java-ide/

This is a general guide for using SpaceVim as a Java IDE, including layer configuration and usage.
Each of the following sections will be covered:

Installation
Language server
Code completion
Code outline
Rename symbol
Javadoc hovers
Syntax lint
Import packages
Jump to test file
running code
Code formatting
REPL

Installation

SpaceVim is a Vim and neovim configuration, so you need to install vim or neovim,
here are two guides for installing neovim and vim8 with +python3 feature.
following the quick start guide to install SpaceVim.

SpaceVim do not enable language layer by default, so you need to enable lang#java layer.
Press SPC f v d to open SpaceVim configuration file, and add following section:

[[layers]]
  name = "lang#java"

Language server

To enable language server protocol support, you may need to enable lsp layer.

[[layers]]
  name = "lsp"
  filetypes = [
    "java"
  ]
  [layers.override_cmd]
    java = [
    "java",
    "-Declipse.application=org.eclipse.jdt.ls.core.id1",
    "-Dosgi.bundles.defaultStartLevel=4",
    "-Declipse.product=org.eclipse.jdt.ls.core.product",
    "-Dlog.protocol=true",
    "-Dlog.level=NONE",
    "-noverify",
    "-Xmx1G",
    "-jar",
    "D:\\dev\\jdt-language-server-latest\\plugins\\org.eclipse.equinox.launcher_1.5.200.v20180922-1751.jar",
    "-configuration",
    "D:\\dev\\jdt-language-server-latest\\config_win",
    "-data",
    "C:\\Users\\Administrator\\.cache\\javalsp"
    ]

You need to replace D:\dev\jdt-language-server-latest\plugins\org.eclipse.equinox.launcher_1.5.200.v20180922-1751.jar with the actual name of the org.eclipse.equinox.launcher jar

The configuration flag can point to either:

config_win, for Windows
config_mac, for MacOS
config_linux, for Linux

The data flag value should be the absolute path to the working directory of the server.
This should be different from the path of the user's project files (which is sent during the initialize handshake).

Code completion

javacomplete2 which has been included in lang#java layer provides omnifunc for java file and deoplete source.
with this plugin and autocomplete layer, the completion popup menu will be opened automatically。

Code outline

The default outline plugin is tagbar, and the key binding is F2. This key binding will open an outline sidebar on the left.

To fuzzy find outline in current buffer, you need to enable a fuzzy find layer, for example denite layer,
then press Leader f o:

Rename symbol

After enable lsp layer for java, you can use SPC l e to rename symbol under the cursor:

Javadoc hovers

The default key binding to get doc of cursor symbol is SPC l d or K:

Syntax lint

checkers layer provides asynchronous linting feature, this layer use neomake by default.
neomake support maven, gradle and eclipse project. it will generate classpath automatically for these project.

within above picture, we can see the checkers layer provides following feature:

list errors and warnings in quickfix windows
sign error and warning position on the left side
show numbers of errors and warnings on statusline
show cursor error and warning information below current line

Import packages

There are two kind features for importing packages, import packages automatically and manually. SpaceVim will import the packages after selecting the class name on popmenu.
Also, you can use key binding <F4> to import the class at the cursor point. If there are more than one class, a menu will be shown below current windows.

Jump to test file

SpaceVim use vim-project to manager the files in a project, you can add a .projections.json to the root of your project with following content:

{
  "src/main/java/*.java": {"alternate": "src/test/java/{dirname}/Test{basename}.java"},
  "src/test/java/**/Test*.java": {"alternate": "src/main/java/{}.java"}
}