命名约定：“from”与“of”方法有什么区别

Question

从命名约定和可用性来看：类中“from”与“of”方法有什么区别？何时创建每一个？

Answer 1

请参阅作为Oracle 提供的java.time教程的一部分发布的指南方法命名约定。

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去引用：

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of

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创建一个实例，其中工厂主要验证输入参数，而不是转换它们。

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\xe2\x80\xa6 和 \xe2\x80\xa6

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from

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将输入参数转换为目标类的实例，这可能会丢失输入中的信息。

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

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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.\n\nZoneId 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.\nZonedDateTime zdt = ZonedDateTime.now( zoneId ) ;\nLocalDate y = LocalDate.from( zdt ) ;                    // Converting between types. Data loss involved, losing (a) time-of-day and (b) time zone.\nLocalDate z = zdt.toLocalDate() ;\n

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查看IdeOne.com 上实时运行的代码。

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x.toString(): 2021-03-27\ny.toString(): 2021-05-25\nz.toString(): 2021-05-25\n

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