三星J7返回每周的第一天为2 [英] Samsung J7 returning first day of week as 2
问题描述
我编写了用于自定义日历的代码，其中使用了日历对象。我使用了getFirstDayOfWeek（）方法来检索每月的第一天。每月加载时，方法 _calendar.getTime（）返回第一个日期。在每个设备上都可以正确返回。但是在三星J7上，它返回的起始日期为2。这是我的三星J7调试器日志
I have written a code for custom calendar where I am using calendar object.I have used the method getFirstDayOfWeek() to retrieve first day of every month.On loading every month the method "_calendar.getTime()" returns the first date. On every device it is returning correctly.But on samsung J7 it returns starting date of week as 2 . Here is my debugger log for samsung J7
java.util.GregorianCalendar [time = ?, areFieldsSet = false，lenient = true，zone =亚洲/ Calcutta，firstDayOfWeek = 2，minimumDaysInFirstWeek = 4，ERA = 1，YEAR = 2016，MONTH = 10，WEEK_OF_YEAR = 41，WEEK_OF_MONTH = 3，DAY_OF_MONTH = 14，DAY_OF_YEAR = 288，DAY_OF_WEEK = 6，DAY_OF_WEEK_IN_MONTH 1，HOUR = 3，HOUR_OF_DAY = 15，MINUTE = 46，SECOND = 58，MILLISECOND = 199，ZONE_OFFSET = 19800000，DST_OFFSET = 0]
java.util.GregorianCalendar[time=?,areFieldsSet=false,lenient=true,zone=Asia/Calcutta,firstDayOfWeek=2,minimalDaysInFirstWeek=4,ERA=1,YEAR=2016,MONTH=10,WEEK_OF_YEAR=41,WEEK_OF_MONTH=3,DAY_OF_MONTH=14,DAY_OF_YEAR=288,DAY_OF_WEEK=6,DAY_OF_WEEK_IN_MONTH=2,AM_PM=1,HOUR=3,HOUR_OF_DAY=15,MINUTE=46,SECOND=58,MILLISECOND=199,ZONE_OFFSET=19800000,DST_OFFSET=0]
对于其他显示为1的设备，它说firstDayOfWeek = 2，那么该解决方案有什么想法？
谢谢。
It says firstDayOfWeek = 2 , for rest of the devices it shows as 1. So any ideas for the solution? Thanks.
推荐答案
tl; dr
- 您似乎将月初与一周的第一天混为一谈。
-
2是表示星期一的硬编码常量。 - 显然，您当前的默认语言环境将星期一视为一周的第一天。
- 改为使用java.time。
- You seem to conflate first-of-month with first-day-of-week.
- The
2is a hard-coded constant representing Monday. - Apparently your current default locale considers Monday to be the first day of the week.
- Use java.time instead.
tl;dr
一周的第一天：
LocalDate.now( ZoneId.of( "America/Montreal" ) )
.with( TemporalAdjusters.previousOrSame( DayOfWeek.MONDAY ) )
每月第一天：
LocalDate.now( ZoneId.of( "Pacific/Auckland" ) )
.with( ChronoField.DAY_OF_MONTH , 1L )
< h1>详细信息
Details
getFirstDayOfWeek（）检索每月的第一天
getFirstDayOfWeek() to retrieve first day of every month
您似乎将一周的第一天和一月的第一天混淆了。
You seem to be confusing first of the week with first of the month.
当然，本月的第一天总是 1 。
The first of the month is always 1 of course.
一周的第一天是星期几，例如星期日或星期一等。 日历 类有所不同，具体取决于语言环境。例如，在北美大部分地区，第一天通常是星期日。在欧洲大部分地区，一周的第一天是星期一。
The first of the week is a day-of-week such as Sunday or Monday etc. The definition of the first day of the week in the Calendar class varies, depending on the Locale. For example, in much of North America, the first day is Sunday commonly. In much of Europe, the first day of the week is Monday.
如果您未指定 Locale ，则 Calendar 类隐式应用JVM的当前默认语言环境。显然，在默认语言环境中，一周的第一天是星期一。我推断是因为您报告了数字 2 。如果您浏览 int 常量 Calendar.MONDAY ，您发现这确实是值<$ c的原始 int $ c> 2 。
If you fail to specify a Locale, the Calendar class implicitly applies the JVM’s current default locale. Apparently in your default locale the first day of the week is Monday. I deduce that because you report the number 2. If you explore the int constant Calendar.MONDAY, you find it is indeed a primitive int of value 2.
Calendar 类的设计决策很多。我认为对星期几的这种不同定义就是其中之一。避免这些麻烦的旧日期时间类的众多原因之一，例如 Calendar 和 Date 。这些类现在已被遗留，由java.time类取代。
The Calendar class has many poor design decisions. I consider this varying definition of day-of-week to be one of them. One of many reasons to avoid these troublesome old date-time classes such as Calendar and Date. These classes are now legacy, supplanted by the java.time classes.
a href = https://docs.oracle.com/javase/8/docs/api/java/time/LocalDate.html rel = nofollow noreferrer> LocalDate 类表示没有日期和时区的仅日期值。
The LocalDate class represents a date-only value without time-of-day and without time zone.
时区对于确定日期至关重要。在任何给定时刻，日期都会在全球范围内变化。例如，在法国巴黎午夜过后的几分钟，虽然仍然是昨天中魁北克省。
A time zone is crucial in determining a date. For any given moment, the date varies around the globe by zone. For example, a few minutes after midnight in Paris France is a new day while still "yesterday" in Montréal Québec.
以 continent格式指定适当的时区名称 / region ，例如 America / Montreal ， 非洲/ Casablanca 或 Pacific / Auckland 。请勿使用3-4个字母的缩写，例如 EST 或 IST ，因为它们不是 真实时区，不是标准化的，甚至不是唯一的（！）。
Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).
ZoneId z = ZoneId.of( "America/Montreal" );
LocalDate today = LocalDate.now( z );
要获取一周的第一天，（a）确定一周的第一天是什么为您（b）使用 <$在 TemporalAdjusters 以获取特定 DayOfWeek 枚举对象。
To get the first day of the week, (a) decide what is the first day of the week for you, (b) use a TemporalAdjuster implementation defined in TemporalAdjusters to get the date for a specific DayOfWeek enum object.
DayOfWeek firstDow = DayOfWeek.MONDAY ;
LocalDate ld = today.with( TemporalAdjusters.previousOrSame( firstDow ) ) ;
要在某天获得 LocalDate 每月，调用 with 方法并从 ChronoField.DAY_OF_MONTH 。
To get a LocalDate for a certain day of month, call the with method and pass an enum object from ChronoField.DAY_OF_MONTH.
LocalDate firstOfMonth = today.with( ChronoField.DAY_OF_MONTH , 1L ) ;
关于java.time
java.time 框架内置于Java 8及更高版本中。这些类取代了麻烦的旧旧版日期时间类，例如 java.util.Date ， Calendar ，& SimpleDateFormat 。
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
现在处于维护模式的Joda-Time 项目建议迁移到 java.time 类。
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
要了解更多信息，请参见 Oracle教程。并在Stack Overflow中搜索许多示例和说明。规范为 JSR 310 。
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
从哪里获取java.time类？
Where to obtain the java.time classes?
- Java SE 8 ， Java SE 9 ，然后是
- 内置。
- 具有捆绑实现的标准Java API的一部分。
- Java 9添加了一些次要功能和修复。
- Java SE 8, Java SE 9, and later
- Built-in.
- Part of the standard Java API with a bundled implementation.
- Java 9 adds some minor features and fixes.
- 许多java.time功能都反向移植到Java 6& 7在> ThreeTen-Backport 中。
- Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
- ThreeTenABP 项目专为Android改编了 ThreeTen-Backport （如上所述）。
- 请参阅 如何使用ThreeTenABP… 。
- The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
- See How to use ThreeTenABP….
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