private static void showError(java.awt.Component parent, String message) {
        JOptionPane.showMessageDialog(parent, message, "Error", JOptionPane.ERROR_MESSAGE);
    }
Utility method for converting a String denoting a file into a URL.

@return a URL pointing to the file or null
jme3-awt-dialogs/src/main/java/com/jme3/awt/AWTSettingsDialog.java