jc.nvim

jc.nvim – successor of vim-javacomplete2 which use neovim's built-in LSP client and Eclipse JDT Language Server.

Read my blog post about it.

Main goal of this project is to migrate functionallty of jc2.

In addition to autocompletion it can:

• organize imports with smart selection regular classes;
• generate code (toString, hashCode, equals, constructors, accessors) with field selection;
• add abstract methods to implementing class;
• execute vimspector debug session;
• automatic installation of jdt.ls and java-debug extension;
• class creation methods from jc2.

Installation

Minimal setup using LazyVim:

return {
  {
    "mfussenegger/nvim-jdtls",
    config = function() end,
  },
  {
    "puremourning/vimspector",
    keys = {
      {
        "<leader>vr",
        "<Cmd>VimspectorReset<cr>",
      },
      {
        "<leader>vb",
        "<Cmd>VimspectorBreakpoints<cr>",
      },
    },
    init = function()
      vim.g.vimspector_enable_mappings = "HUMAN"
    end,
  },
  {
    dir = "artur-shaik/jc.nvim",
    name = "jc.nvim",
    dependencies = {
      "puremourning/vimspector",
      "mfussenegger/nvim-jdtls",
      "williamboman/mason.nvim",
    },
    ft = { "java" },
    opts = {
      java_exec = "/path/to/candidates/java/17.0.7-oracle/bin/java",
      keys_prefix = "'j",
      settings = {
        java = {
          configuration = {
            runtimes = {
              {
                name = "JavaSE-11",
                path = "/path/to/candidates/java/11.0.12-open/",
                default = true,
              },
            },
          },
        },
      },
    },
  },
}

lspconfig:

return {
  {
    "neovim/nvim-lspconfig",
    opts = {
      servers = {
        jdtls = {},
      },
      setup = {
        jdtls = function()
          return true
        end,
      },
    },

For triggering autocompletion automatically consider configure nvim-cmp.

Configurations

g:jc_default_mappings – apply default mappings (default: 1)

g:jc_autoformat_on_save – execute code autoformatting on file save (default: 1)

Commands

• JCdebugAttach – start debug session with vimspector attaching to debug port;
• JCdebugLaunch – start debug session with vimspector executing main class;
• JCdebugWithConfig – start debug session using predefined vimspector's configuration;
• JCimportsOrganizeSmart – automatically organize imports using regular classes list;
• JCimportsOrganize – automatically organize imports choosing from available classes list;
• JCgenerateToString – choose fields and method to generate toString;
• JCgenerateHashCodeAndEquals – choose fields to generate hashCode and equals;
• JCgenerateAccessors – choose fields for accessors generation;
• JCgenerateAccessorGetter – generate getter for a field;
• JCgenerateAccessorSetter – generate setter for a field;
• JCgenerateAccessorSetterGetter – generate getter and setter for a field;
• JCgenerateConstructorDefault – generate constructor with no arguments;
• JCgenerateConstructor – choose fields for constructor;
• JCgenerateAbstractMethods – generate abstract methods;
• JCgenerateClass – start class generation user input prompt;
• JCtoggleAutoformat – enable/disable autoformat file on save;

Using nvim-jdtls:

• JCrefactorExtractVar – extract variable;
• JCrefactorExtractMethod – extract method;
• JCutilJshell – execute java shell;
• JCutilBytecode – extract bytecode for class;
• JCutilJol – analyze object layout scheme using jol.jar;
• JCutilUpdateConfig – update current project's configuration.

Default mappings

  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>ji", "<cmd>lua require('jc.jdtls').organize_imports(true)<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jI", "<cmd>lua require('jc.jdtls').organize_imports(false)<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "i", "<C-j>i", "<cmd>lua require('jc.jdtls').organize_imports()<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jts", "<cmd>lua require('jc.jdtls').generate_toString()<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jeq", "<cmd>lua require('jc.jdtls').generate_hashCodeAndEquals()<CR>", opts)

  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jA", "<cmd>lua require('jc.jdtls').generate_accessors()<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>js", "<cmd>lua require('jc.jdtls').generate_accessor('s')<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jg", "<cmd>lua require('jc.jdtls').generate_accessor('g')<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>ja", "<cmd>lua require('jc.jdtls').generate_accessor('gs')<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "i", "<C-j>s", "<cmd>lua require('jc.jdtls').generate_accessor('s')<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "i", "<C-j>g", "<cmd>lua require('jc.jdtls').generate_accessor('g')<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "i", "<C-j>a", "<cmd>lua require('jc.jdtls').generate_accessor('sg')<CR>", opts)

  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jc", "<cmd>lua require('jc.jdtls').generate_constructor(nil, nil, {default = false})<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jcc", "<cmd>lua require('jc.jdtls').generate_constructor(nil, nil, {default = true})<CR>", opts)

  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jam", "<cmd>lua require('jc.jdtls').generate_abstractMethods()<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "i", "<C-j>am", "<cmd>lua require('jc.jdtls').generate_abstractMethods()<CR>", opts)
  
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jda", "<cmd>lua require('jc.vimspector').debug_attach()<CR>", opts)

-- using `jdtls`
  vim.api.nvim_buf_set_keymap(bufnr, "v", "<leader>jre", "<Esc><Cmd>lua require('jdtls').extract_variable(true)<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<leader>jre", "<Cmd>lua require('jdtls').extract_variable()<CR>", opts)
  vim.api.nvim_buf_set_keymap(bufnr, "v", "<leader>jrm", "<Esc><Cmd>lua require('jdtls').extract_method(true)<CR>", opts)

Class creation

Prompt scheme, for class creation:

template:[subdirectory]:/package.ClassName extends SuperClass implements Interface(String str, public Integer i):contructor:toString:equals

A: (optional) template - which will be used to create class boilerplate. Some existed templates: junit, interface, exception, servlet, etc;

B: (optional) subdirectory in which class will be put. For example: test, androidTest;

C: class name and package. With / will use backsearch for parent package to put in it. Without / put in relative package to current;

D: (optional) extends and implements classes will be automatically imported;

E: (optional) private str variable, and public i variable will be added to class;

F: (optional) contructor using all fields and toString will be created. Also hashCode and equals can be used.