java default formatter

ftplugin/java.lua

@@ -1,3 +1,28 @@
+vim.cmd "let proj = FindRootDirectory()"
+local root_dir = vim.api.nvim_get_var "proj"
+
+-- use the global prettier if you didn't find the local one
+local prettier_instance = root_dir .. "/node_modules/.bin/prettier"
+if vim.fn.executable(prettier_instance) ~= 1 then
+  prettier_instance = O.lang.tsserver.formatter.exe
+end
+
+O.formatters.filetype["java"] = {
+  function()
+    return {
+      exe = prettier_instance,
+      -- TODO: allow user to override this
+      args = { "--stdin-filepath", vim.api.nvim_buf_get_name(0) },
+      stdin = true,
+    }
+  end,
+}
+
+require("formatter.config").set_defaults {
+  logging = false,
+  filetype = O.formatters.filetype,
+}
+
 if require("lv-utils").check_lsp_client_active "jdtls" then
   return
 end