DateTimeFormatter自动更正无效（语法上可能）的日历日期 [英] DateTimeFormatter auto-corrects invalid (syntactically possible) calendar date

问题描述

Java DateTimeFormatter 当您尝试超出可能范围的日期时抛出异常，例如：

Java DateTimeFormatter throws an exception for when you try a date that goes outside of a possible range, for example:

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("M/d/yyyy");
String dateString = "12/32/2015";
LocalDate ld = LocalDate.parse(dateString, dtf);

将抛出：

Exception in thread "main" java.time.format.DateTimeParseException: Text '12/32/2015' could not be parsed: Invalid value for DayOfMonth (valid values 1 - 28/31): 32

但是，当我输入一个无效的日历日期时，他们的标准仍然是语法上可行的，它会自动更正为有效日期，例如：

But when I enter an invalid calendar date that is still syntactically possible by their standards, it autocorrects it to be a valid date, for example:

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("M/d/yyyy");
String dateString = "2/31/2015";
LocalDate ld = LocalDate.parse(dateString, dtf);

它成功解析但自动更正为 2015-02-28 。我不想这个行为，我希望它在日期不是有效的日历日期时仍然抛出异常。有没有一个可以设置的内置选项，或者我真的需要尝试手动筛选出这些实例？

it successfully parses but autocorrects to 2015-02-28. I don't want this behavior, I want it to still throw an exception when the date is not a valid calendar date. Is there a built-in option I can set for that to happen, or do I really have to try to manually sift out these instances?

推荐答案

您可以使用 STRICT 解析器样式：

You can use a STRICT resolver style:

import static java.time.format.ResolverStyle.STRICT;

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("M/d/uuuu").withResolverStyle(STRICT);

默认情况下， ofPattern 使用 a SMART 解析器样式将使用合理的默认值。

By default, ofPattern uses a SMART resolver style which will use reasonable defaults.

请注意，我已经使用 uuuu 的 yyyy ，即 YEAR ，而不是 YEAR_OF_ERA 。假设你是一个公历的系统，这两个在当前时代（1年级以上）相当多年。差异在上面的链接中有更多的细节。

Note that I have used uuuu instead of yyyy, i.e. YEAR instead of YEAR_OF_ERA. Assuming you are in a Gregorian calendar system, the two are equivalent for years in the current era (year 1 or greater). The difference is explained in more details in the links above.

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