Java (jdtls) Configuration for cross-platform

The Current setup is configured to work with arch and Debian distros.To configure support for Windows, macOS, and Linux, with dynamic path detection, Use the following Guidance to configure the jdtls (Java Development Tools Language Server). This setup supports features like code completion, navigation, CodeLens, inlay hints, and formatting.

Modify the following file /lua/core/lsp.lua

Prerequisites and Setup Instructions

• Neovim: Version 0.9.x or higher
• Plugins:
  • neovim/nvim-lspconfig
  • williamboman/mason.nvim
  • hrsh7th/cmp-nvim-lsp
• Java:
  • JDK 21 (recommended)
  • Optionally JDK 17
• Environment Variables (optional):
  • JAVA_HOME: Path to JDK 21
  • JAVA_17_HOME: Path to JDK 17
  • JAVA_21_HOME: Path to JDK 21
  • LOMBOK_JAR: Path to Lombok JAR (if not using Mason’s default)

⚙️ Setup Instructions

• Ensure mason.nvim is configured to install jdtls:

require("mason-lspconfig").setup({
  ensure_installed = { "jdtls" }
})

```lua
-- Java (jdtls) Configuration
local function get_jdtls_paths()
  local java_home = os.getenv("JAVA_HOME") or (
    vim.fn.has("win32") == 1 and "C:\\Program Files\\Java\\jdk-21" or
    vim.fn.has("mac") == 1 and "/Library/Java/JavaVirtualMachines/jdk-21.jdk/Contents/Home" or
    "/usr/lib/jvm/java-21-openjdk"
  )
  local mason_path = vim.fn.stdpath("data") .. (vim.fn.has("win32") == 1 and "\\mason\\packages\\jdtls" or "/mason/packages/jdtls")
  local lombok_path = os.getenv("LOMBOK_JAR") or (mason_path .. (vim.fn.has("win32") == 1 and "\\lombok.jar" or "/lombok.jar"))
  local config_dir = mason_path .. (
    vim.fn.has("win32") == 1 and "\\config_win" or
    vim.fn.has("mac") == 1 and "/config_mac" or
    "/config_linux"
  )
  local data_dir = (vim.fn.stdpath("cache") .. (vim.fn.has("win32") == 1 and "\\jdtls-workspace\\" or "/jdtls-workspace/")) .. vim.fn.fnamemodify(vim.fn.getcwd(), ':p:h:t')
  return java_home, lombok_path, config_dir, data_dir
end

local java_home, lombok_path, config_dir, data_dir = get_jdtls_paths()
local java_17_path = os.getenv("JAVA_17_HOME") or (
  vim.fn.has("win32") == 1 and "C:\\Program Files\\Java\\jdk-17" or
  vim.fn.has("mac") == 1 and "/Library/Java/JavaVirtualMachines/jdk-17.jdk/Contents/Home" or
  "/usr/lib/jvm/java-17-openjdk"
)
local java_21_path = os.getenv("JAVA_21_HOME") or (
  vim.fn.has("win32") == 1 and "C:\\Program Files\\Java\\jdk-21" or
  vim.fn.has("mac") == 1 and "/Library/Java/JavaVirtualMachines/jdk-21.jdk/Contents/Home" or
  "/usr/lib/jvm/java-21-openjdk"
)

lspconfig.jdtls.setup({
  cmd = {
    java_home .. (vim.fn.has("win32") == 1 and "\\bin\\java.exe" or "/bin/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=ALL',
    '-Xmx1g',
    '--add-modules=ALL-SYSTEM',
    '--add-opens', 'java.base/java.util=ALL-UNNAMED',
    '--add-opens', 'java.base/java.lang=ALL-UNNAMED',
    '-javaagent:' .. lombok_path,
    '-jar', vim.fn.glob(mason_path .. (vim.fn.has("win32") == 1 and "\\plugins\\org.eclipse.equinox.launcher_*.jar" or "/plugins/org.eclipse.equinox.launcher_*.jar")),
    '-configuration', config_dir,
    '-data', data_dir,
  },
  root_dir = lspconfig.util.root_pattern('pom.xml', 'build.gradle', 'gradlew', 'mvnw', '.git'),
  settings = {
    java = {
      referencesCodeLens = { enabled = true },
      implementationsCodeLens = { enabled = true },
      inlayHints = { parameterNames = { enabled = "all" } },
      maven = { downloadSources = true },
      references = { includeDecompiledSources = true },
      format = { enabled = true },
      completion = {
        favoriteStaticMembers = {
          "org.junit.Assert.*",
          "org.junit.Assume.*",
          "org.junit.jupiter.api.Assertions.*",
          "java.util.Objects.requireNonNull",
          "java.util.Objects.requireNonNullElse",
        },
        importOrder = { "java", "javax", "com", "org" },
      },
      configuration = {
        runtimes = {
          { name = "JavaSE-17", path = java_17_path, default = true },
          { name = "JavaSE-21", path = java_21_path },
        },
      },
    },
  },
  init_options = { bundles = {} },
  on_attach = on_attach,
  capabilities = capabilities,
})