@FXML private void createDirButtonClicked(final ActionEvent event) { final File parent = assertNotNull("getSelectedDirectory()", getSelectedDirectory()); final String dirName = showCreateOrRenameDialog( "Create folder", "What should be the new folder's name?", parent, null, (name) -> !createFile(parent, name).exists()); if (dirName != null) { final File directory = createFile(parent, dirName); directory.mkdirs(); if (!directory.isDirectory()) showErrorDialog( "Failed to create directory!", "The directory could not be created! Maybe you're missing the required permissions?!"); else { refresh(); getSelectedFiles().clear(); getSelectedFiles().add(directory); } } }