(bug记录)Cause: java.lang.IllegalArgumentException: invalid comparison: java.util.Arrays$ArrayList and java.lang.String

报错样式

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 

Error querying database.  Cause: java.lang.IllegalArgumentException: invalid comparison: java.util.Arrays$ArrayList and java.lang.String

Cause: java.lang.IllegalArgumentException: invalid comparison: java.util.Arrays$ArrayList and java.lang.String

DAO(Mapper)层代码

List<String>queryRenewalAnnualCycles(@Param("renewalStrategyConfigVO")RenewalStrategyConfigVO renewalStrategyConfigVO,
                                     @Param("policyStatusList")List<String> policyStatusList,
                                     @Param("templateList")List<String> templateList);

mapper.xml代码

<select id="queryRenewalAnnualCycles" resultType="java.lang.String">    
    select distinct renewal_annual_cycles    
    from online_policy_insure_info a    
    where a.is_deleted != 'N'    
    and a.renewal_annual_cycles IS NOT NULL    
    and a.renewal_annual_cycles != ''    
    <if test="renewalStrategyConfigVO.goodsCode!=null and renewalStrategyConfigVO.goodsCode!=''">
        and a.plan_code in 
        (select product_code        
        from cms_goods_product        
        where goods_code = #{renewalStrategyConfigVO.goodsCode})    
    </if>    
    <if test="renewalStrategyConfigVO.insurerCode!=null and renewalStrategyConfigVO.insurerCode!=''">
        and a.insurer_code = #{renewalStrategyConfigVO.insurerCode}    
    </if>    
    <if test="policyStatusList!=null and policyStatusList!= ''">        
        and a.policy_status in        
        <foreach collection="policyStatusList" item="policyStatus" open="(" close=")" separator=",">            
            #{policyStatus}        
        </foreach>    
    </if>    
    <if test="templateList!=null and templateList!= ''">        
        and a.id in (select e.policy_id        
        from online_policy_pay_sign e        
        inner join cashier_template_config f on e.sign_template_code = f.template_code        
        inner join cashier_merchant_config g on f.merchant_code = g.merchant_code        
        where g.owner in        
        <foreach collection="templateList" item="template" open="(" close=")" separator=",">            
            #{template}        
        </foreach>)    
    </if>
</select>

报错解释

这个错误意味着在MyBatis执行数据库查询时出现了问题，导致无法正确比较某些值。错误提示指出了比较无效的对象类型，即"java.util.Arrays$ArrayList"和"java.lang.String"。

这通常意味着在MyBatis的SQL语句中，出现了对不同类型的数据进行比较的情况。比如，可能在WHERE子句或JOIN条件中，试图比较一个ArrayList类型的值和一个String类型的值，这是不允许的。

通过比对mapper代码和xml代码可以看到，我们在标签中判断两个List属性的参数policyStatusList、templateList时分别添加了

and policyStatusList!= ''

and templateList!= ''

而这两个条件这就是造成报错的根源所在......（原本想添加的限制是集合不为null且不为空，习惯性按照字符串判空值的写法来写list类型，造成了bug）

解决方案

1. 条件去除 != ''

2. 改成 and templateList.size() > 0、and templateList.size() > 0即可