如何在年龄计算器中计算输入日期和当前日期之间的确切天数？

Question

val theDate=sdf.parse(selectedDate)

            theDate?.let {

                val selectedDateInMin=theDate.time / 60000
                val selectedDateInYear=(theDate.time/ 31536000000)
                val selectedDateInMonth=(theDate.time)/2629746000
                val selectedDateInDay=(theDate.time)/86400000

                val currentDate=sdf.parse(sdf.format(System.currentTimeMillis()))
                currentDate?.let {

                    val currentDateInMin=currentDate.time/60000
                    val currentDateInYear=(currentDate.time/ 31536000000)
                    val currentDateInMonth=(currentDate.time)/2629746000
                    val currentDateInDay=(currentDate.time)/86400000

                    val differenceInMin = currentDateInMin-selectedDateInMin
                    val differenceInYear=currentDateInYear-selectedDateInYear-1

                    val leap_days=(differenceInYear*(0.24)).toInt()

                    val differenceInMonth=currentDateInMonth-selectedDateInMonth-(differenceInYear*12)

                    val differenceInDay=currentDateInDay-selectedDateInDay-(differenceInYear*365)-(differenceInMonth*31)-leap_days

当我计算 Days 差异时，我必须减去包含在 month 差异中的天数。那么我将如何计算该月是否有 28 天或 31 天或 30 天，什么没有。我必须乘以 differenceInMonth 吗？我将如何概括获取特定月份中确切天数的公式，例如2个月或4个月有多少天？

Answer 1

import java.text.SimpleDateFormat
import java.time.Duration

val sdf = SimpleDateFormat("yyyy-MM-dd hh:mm:ss")

val theDate= sdf.parse("2022-03-14 17:09:18")
val now = sdf.parse(sdf.format(System.currentTimeMillis()))

val duration = Duration.between(now.toInstant(), theDate.toInstant()).toDays()

println("$duration days")