Java8特性——Optional

當項目運行時拋出 NullPointerException 空指針異常的錯誤時，可以

考慮使用Optional來處理null的問題。

例子如下：

@Override
    public ReplyStatusResponse replyStatusList(Long replyId) {
        LOGGER.debug(CommonLogDomain.BUSINESS, "replyStatusList，replyId:{}", replyId);
        ReplyStatusResponse replyStatusResponse = new ReplyStatusResponse();
        PostReplyInfo r = postReplyInfoService.selectByPrimaryKey(replyId);
        Integer r1 = Optional.ofNullable(r).map(PostReplyInfo::getSelfPrivate).map(t -> t.intValue()).orElse(0);
        Integer r2 = Optional.ofNullable(r).map(PostReplyInfo::getPortalHidden).map(t -> t.intValue()).orElse(0);
        Integer replyIdStatus = (r1 + r2 == 0) ? 0 : 1;
        replyStatusResponse.setReplyIdStatus((replyIdStatus.byteValue()));
        return replyStatusResponse;
    }

基本語法：

Optional.ofNullable(r).map(PostReplyInfo::getSelfPrivate).map(t -> t.intValue()).orElse(0);