java - 命名约定 : What is the difference between "from" vs "of" methods

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从命名约定和可用性:
类中的“from”与“of”方法有什么区别？什么时候创建每个？

Answer 1

看指南Method Naming Conventions作为 the java.time tutorial 的一部分发布由 Oracle 提供。
报价:

of

Creates an instance where the factory is primarily validating the input parameters, not converting them.

… 和 …

from

Converts the input parameters to an instance of the target class, which may involve losing information from the input.

有关实际示例，请参阅 java.time 类，例如 LocalDate , LocalTime , Instant , OffsetDateTime , ZonedDateTime , LocalDateTime ， 等等。

LocalDate x = LocalDate.of( 2021 , Month.MARCH , 27 ) ;  // Directly injecting the three parts of a date (year, month, day) without any need to parse or process the inputs other than basic data validation such as day within appropriate range of 1-28/31 for that year-month.

ZoneId zoneId = ZoneId.of( "Africa/Casablanca" ) ;       // This string is the official name of this time zone. Can be mapped directly from name to object, with no real processing, parsing, or conversions involved.
ZonedDateTime zdt = ZonedDateTime.now( zoneId ) ;
LocalDate y = LocalDate.from( zdt ) ;                    // Converting between types. Data loss involved, losing (a) time-of-day and (b) time zone.
LocalDate z = zdt.toLocalDate() ;

见 code run live at IdeOne.com .

x.toString(): 2021-03-27
y.toString(): 2021-05-25
z.toString(): 2021-05-25