DST更改导致java.text.ParseException：无法解析的日期 [英] DST changes caused an java.text.ParseException: Unparseable date

问题描述

以下是引发异常的代码段：

Following is the code snippet which is throwing an exception:

SimpleDateformat dateFormatter = new SimpleDateFormat("yyyyMMddHHmm");
Date date = dateFormatter.parse("201710010200");

上面的代码对凌晨2:00之后的所有日期均抛出异常。一直运行到凌晨01:30

The code above threw exception for all the dates after 2:00 A.M. It ran well till 01:30 A.M.

已配置了夏令时（我使用的是澳大利亚/悉尼时区）。

DayLight saving time was configured (I'm using Australia/Sydney timezone).

之后，我可以看到凌晨3:00的日志
凌晨2:00之间的时间和凌晨3:00

After that, I could see logs of 3:00 A.M. Time between 2:00 A.M. and 3:00 A.M. is not logged too.

日志：

01 Oct 03:02： 01错误：无法解析的日期： 201710010200

01 Oct 03:02:01 ERROR : Unparseable date: "201710010200"

原因：java.text.ParseException：无法解析的日期： 201710010200
在java.text.DateFormat.parse（DateFormat.java:357）

Caused by: java.text.ParseException: Unparseable date: "201710010200" at java.text.DateFormat.parse(DateFormat.java:357)

解决了日期字符串 201710010200 无法解析，并指定了正确的日期格式的问题？

What could be the fix of the problem of the date string "201710010200" not getting parsed, with the right date format specified?

推荐答案

您正在尝试解析未发生的日期/时间。

You're trying to parse a date/time that didn't occur.

我们现在知道这是在悉尼时区。 2017年10月1日在悉尼，凌晨2点钟。如果您每分钟查看一次时钟，则会看到：

We now know that this was in the Sydney time zone. At 2am on October 1st 2017 in Sydney, the clocks went forward to 3am. If you were looking at a clock every minute you'd see:

• 01:58


• 01:59


• 03:00


• 03:01

• 01:58
• 01:59
• 03:00
• 03:01

因此，在该时区根本没有发生凌晨2点（含）到凌晨3点（不含）之间的任何日期/时间。我们不知道是什么导致了您要解析的值，但是：

So any date/time between 2am (inclusive) and 3am (exclusive) simply didn't occur in that time zone. We don't know what produced the values you're trying to parse, but:

• 如果它们是时间戳，那几乎可以肯定最好同时格式化和解析UTC。如果产生它们的时区对于将来的分析很重要，则与UTC保持偏移，并可能与时区ID保持偏移。


• 如果它们是未链接的日期/时间值到任何特定时区，请不要将它们解析为在时区。理想情况下，使用Java 8的 java.time 包并将其解析为 LocalDateTime 值

• If they're timestamps, it would almost certainly be better to both format and parse in UTC. Keep an offset from UTC and potentially a time zone ID if the time zone in which they were produced is important for future analysis.
• If they're date/time values which aren't linked to any particular time zone, don't parse them as if they were in a time zone. Ideally, use Java 8's java.time package and parse them as LocalDateTime values

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