class EmotionQueryService {

    /**
     * Logger.
     */
    private static final Logger LOGGER = LogManager.getLogger(EmotionQueryService.class);

    /**
     * Common used emoji string.
     */
    private static final String COMMON_USED = "smile,flushed,joy,sob,yum,trollface,tada,heart,+1,ok_hand,pray";

    /**
     * Emotion repository.
     */
    @Inject
    private EmotionRepository emotionRepository;

    /**
     * Gets a user's emotion (emoji with type=0).
     *
     * @param userId the specified user id
     * @return emoji string join with {@code ","}, returns a common used emoji string if not found
     */
    public String getEmojis(final String userId) {<FILL_FUNCTION_BODY>}
}

        try {
            final String ret = emotionRepository.getUserEmojis(userId);
            if (StringUtils.isBlank(ret)) {
                return COMMON_USED;
            }

            return ret;
        } catch (final RepositoryException e) {
            LOGGER.log(Level.ERROR, e.getMessage());

            return COMMON_USED;
        }
    
<no_super_class>