Kotlin：获取两个日期之间的差异（现在和上一个日期）

Question

抱歉，如果类似问题被问了太多次，但我找到的每个答案似乎都有一个或多个问题。

我有一个字符串形式的日期：例如：“04112005”

这是约会。2005 年 11 月 4 日。

我想获得当前日期和此日期之间的年数和天数差异。

到目前为止，我的代码获取年份并减去它们：

fun getAlderFraFodselsdato(bDate: String): String {
    val bYr: Int = getBirthYearFromBirthDate(bDate)
    var cYr: Int = Integer.parseInt(SimpleDateFormat("yyyy").format(Date()))

    return (cYr-bYr).toString()
}

但是，自然而然，这是非常不准确的，因为不包括月份和日期。

我尝试了几种方法来创建 Date、LocalDate、SimpleDate 等对象，并使用它们来计算差异。但出于某种原因，我没有让他们中的任何一个工作。

我需要创建当前年、月和日的日期（或类似）对象。然后我需要从一个包含月份和年份（“04112005”）的字符串创建相同的对象。然后我需要得到这些之间的差异，以年、月和日为单位。

所有提示表示赞赏。

Answer 1

I would use java.time.LocalDate for parsing and today along with a java.time.Period that calculates the period between two LocalDates for you.
See this example:

fun main(args: Array<String>) {
    // parse the date with a suitable formatter
    val from = LocalDate.parse("04112005", DateTimeFormatter.ofPattern("ddMMyyyy"))
    // get today's date
    val today = LocalDate.now()
    // calculate the period between those two
    var period = Period.between(from, today)
    // and print it in a human-readable way
    println("The difference between " + from.format(DateTimeFormatter.ISO_LOCAL_DATE)
            + " and " + today.format(DateTimeFormatter.ISO_LOCAL_DATE) + " is "
            + period.getYears() + " years, " + period.getMonths() + " months and "
            + period.getDays() + " days")
}

The output for a today of 2020-02-21 is

fun main(args: Array<String>) {
    // parse the date with a suitable formatter
    val from = LocalDate.parse("04112005", DateTimeFormatter.ofPattern("ddMMyyyy"))
    // get today's date
    val today = LocalDate.now()
    // calculate the period between those two
    var period = Period.between(from, today)
    // and print it in a human-readable way
    println("The difference between " + from.format(DateTimeFormatter.ISO_LOCAL_DATE)
            + " and " + today.format(DateTimeFormatter.ISO_LOCAL_DATE) + " is "
            + period.getYears() + " years, " + period.getMonths() + " months and "
            + period.getDays() + " days")
}