Java夏令时如何确定"lost"小时？

Question

我想知道 DateTime "2020-03-29 02:15" 是否因时间变化而存在。
我找到了ZoneOffsetTransitionclass，里面有一个isGap()的方法，但是我不明白怎么用

Answer 1

我会简单地转换为 ZonedDateTime 并返回。 ZonedDateTime坚持选择一个已有的时间，所以如果我们找回相同的时间，那是真的。

    ZoneId zone = ZoneId.of("Europe/Berlin");
    DateTimeFormatter formatter = new DateTimeFormatterBuilder()
            .append(DateTimeFormatter.ISO_LOCAL_DATE)
            .appendLiteral(' ')
            .append(DateTimeFormatter.ISO_LOCAL_TIME)
            .toFormatter();

    String dateTimeString = "2020-03-29 02:15";

    LocalDateTime dateTime = LocalDateTime.parse(dateTimeString, formatter);
    LocalDateTime check = dateTime.atZone(zone).toLocalDateTime();
    if (check.equals(dateTime)) {
        System.out.println("This time exists");
    } else {
        System.out.println("This time does not exist; it is in the spring gap.");
        System.out.println("We got " + check);
    }

输出为：

This time does not exist; it is in the spring gap.
We got 2020-03-29T03:15

来自 LocalDateTime.atZone() 的文档：

In the case of a gap, where clocks jump forward, there is no valid offset. Instead, the local date-time is adjusted to be later by the length of the gap. For a typical one hour daylight savings change, the local date-time will be moved one hour later into the offset typically corresponding to "summer".

Documentation link

Java夏令时如何确定"lost"小时？

Java How to determine the "lost" hour when changing to summertime?

java

datetime

timezone-offset