MyBatis同时返回emptyList（）和null

Question

以下是我的myBatis请求，它应该返回一个列表：

@Mapper
public interface ClientAccessMapper {
    List<ClientAccess> findByClientAndPartnerWithAutoRenewal(@Param("clientId") Long clientId,
                                                             @Param("partner") String partner,
                                                             @Param("autoRenewal") Boolean autoRenewal);
}

<select id="findByClientAndPartnerWithAutoRenewal" resultMap="ClientAccessResult">
        select * from client_access
        where client_id = #{clientId}
            and partner = #{partner}
        <if test="autoRenewal != null">
            and auto_renewal = #{autoRenewal}
        </if>
        order by id
    </select>

有时请求返回“null”而不是空列表。得到后，我有一个检查块：

final List<ClientAccess> clientAccesses = clientAccessMapper.findByClientAndPartnerWithAutoRenewal(client, partner, true);
        if (clientAccesses.isEmpty()) {/**/}

我的clientaccesses.isempty()有时会生成NPE，因为null而不是大小为0的列表。什么会是问题？

Answer 1

可能是空指针。推荐用途：

CollectionUtils.isEmpty(priceList)