kotlin 通过 下标比对

  //通过凭证日期排序
        recordList.sortBy({it.loanDate})

        var certificateNumber = 1
        recordList.forEachIndexed{index,item ->
            (index > 0).y {
                (item.loanDate == recordList.get(index - 1).loanDate).y {
                    item.certificateNumber = certificateNumber
                } other {
                    certificateNumber++
                    item.certificateNumber = certificateNumber
                }
            } other {
                item.certificateNumber = certificateNumber
            }

        }