JDK dateformatter 在德语语言环境中解析 DayOfWeek,java8 与 java9 [英] JDK dateformatter parsing DayOfWeek in German locale, java8 vs java9
问题描述
我在 Java 8 (1.8.0_77) 和 Java 9 (Java HotSpot(TM) 64-Bit Server VM (build 9+181,混合模式))中尝试了一些代码
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("eee", Locale.GERMAN);DayOfWeek mo = dtf.parse("Mo", DayOfWeek::from);System.out.println("mo = " + mo);
我不太熟悉这些类的细节,但在 Java 8 中这是有效的,打印:
<块引用>mo = 星期一
在 Java 9 中,它失败了
<块引用>线程main"中的异常 java.time.format.DateTimeParseException: 无法在索引 0 处解析文本Mo"在 java.base/java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1988)在 java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1890)在 day.main(day.java:10)
任何想法,这是否可重现?
所以,在格式化时:使用此代码:
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("eee", Locale.GERMAN);字符串格式 = dtf.format(DayOfWeek.MONDAY);System.out.println("格式 = " + 格式);
jdk1.8.0-77:
<块引用>格式 = 莫
jdk-9(构建 9+181)
<块引用>格式 = 莫.
编辑/注意:如评论中所链接,迁移指南 对此类实现提出了类似的警告 -
<块引用>如果您的应用程序成功启动,请仔细查看您的测试并确保行为与 JDK 8 上的相同.例如,很少有早期采用者注意到他们的日期和货币是格式不同.请参阅 使用 CLDR 语言环境默认数据.
I have tried some code in Java 8 (1.8.0_77) and Java 9 (Java HotSpot(TM) 64-Bit Server VM (build 9+181, mixed mode))
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("eee", Locale.GERMAN);
DayOfWeek mo = dtf.parse("Mo", DayOfWeek::from);
System.out.println("mo = " + mo);
I am not too familiar with details of those classes, but in Java 8 this works, printing:
mo = MONDAY
In Java 9, however it fails
Exception in thread "main" java.time.format.DateTimeParseException: Text 'Mo' could not be parsed at index 0 at java.base/java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1988) at java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1890) at day.main(day.java:10)
Any ideas, is this reproducible?
so, when formating: using this code:
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("eee", Locale.GERMAN);
String format = dtf.format(DayOfWeek.MONDAY);
System.out.println("format = " + format);
jdk1.8.0-77:
format = Mo
jdk-9 (build 9+181)
format = Mo.
This seems to be there in java-9 due to the current implementation of CLDR date-time-patterns with the implementation of JEP - 252 which states that
Use locale data from the Unicode Consortium's Common Locale Data Repository (CLDR) by default.
Localized patterns for the formatting and translation of display strings, such as the locale name, may be different in some locales.
To enable behavior compatible with JDK 8, set the system property
java.locale.providers
to a value with COMPAT ahead of CLDR.
And to second the data part of it, the international components for Unicode in German locale which has the following relevant information can justify that the behavior is intentional -
Edit/Note: As linked in the comments, the migration guide states a similar warning for such implementations -
If your application starts successfully, look carefully at your tests and ensure that the behavior is the same as on JDK 8. For example, a few early adopters have noticed that their dates and currencies are formatted differently. See Use CLDR Locale Data by Default.
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