mybatis異常: invalid comparison: java.util.ArrayList and java.lang.String] with root cause

mybatis中使用動態sql，報錯： invalid comparison: java.util.ArrayList and java.lang.String] with root cause

是由於  list != ' ' 導致的,引起了集合與string類型的比較

<if test="lsit != null and list != ''">
     B.COMMID IN (
     <foreach collection="list" item="commId" index="index" separator=",">
        #{commId,jdbcType=VARCHAR}
     </foreach>
     )
</if>

修改為

<if test="lsit != null and list.size > 0">
     B.COMMID IN (
     <foreach collection="list" item="commId" index="index" separator=",">
        #{commId,jdbcType=VARCHAR}
     </foreach>
     )
</if>