Neovim: add function to run java code

home/.config/nvim/ftplugin/java.lua

@@ -42,3 +42,45 @@ require("jdtls").start_or_attach({
 })
 
 require("plugins.mason").map_keys()
+
+function RunJava()
+  local function show_output(output)
+    vim.cmd("split")
+    vim.cmd("enew")
+    vim.fn.append(0, output)
+    --vim.cmd("1d") -- Remove the empty first line
+    vim.bo[0].modifiable = false
+  end
+
+  local filename = vim.fn.expand("%") -- Get the current file name
+  local class_name = vim.fn.fnamemodify(filename, ":r") -- Extract the class name
+  local compile_cmd = "javac " .. filename
+  local run_cmd = "java " .. class_name
+
+  -- Create a temporary file to capture the compile output
+  local temp_file = vim.fn.tempname()
+
+  -- Run the compilation command and save the output to the temporary file
+  local compile_exit_code = vim.fn.system(compile_cmd .. " > " .. temp_file .. " 2>&1")
+
+  -- Check the exit code of the compile command
+  if compile_exit_code == 0 then
+    -- Compilation was successful, run the Java program
+    show_output(vim.fn.systemlist(run_cmd))
+  else
+    -- Compilation failed, display the error output from the temporary file
+    show_output(vim.fn.readfile(temp_file))
+  end
+
+  -- Clean up the temporary file and class file
+  vim.fn.delete(temp_file)
+  vim.fn.delete(vim.fn.expand("%:p:h") .. "/" .. class_name .. ".class")
+end
+
+-- Define a VimScript command to execute the Lua function
+vim.api.nvim_exec(
+  [[
+  command! RunJava lua RunJava()
+]],
+  false
+)