using checkstyle with flymake

flymake_checkstyle.el

;; flymake + checkstyle
(require 'flymake-cursor)
(add-hook 'java-mode-hook
          '(lambda ()
             (flymake-mode t)))
(when (load "flymake" t)
  (defun flymake-java-checkstyle-init ()
    (let* ((temp-file (flymake-init-create-temp-buffer-copy
                       'flymake-create-temp-inplace))
           (local-file (file-relative-name
                        temp-file
                        (file-name-directory buffer-file-name))))
      (list "/opt/bin/checkstyle.sh" (list local-file))))
  (add-to-list 'flymake-allowed-file-name-masks
               '("\\.java\\'" flymake-java-checkstyle-init)))