如何在Kotlin中获取本周的开始和结束日期以及上周的开始和结束日期。

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英文:

How to get Thisweek start and end date and Lastweek start and end date in Kotlin

问题

我需要获取本周的开始日期，如2023-02-20，以及上周的开始日期和结束日期。

开始日期将是星期一。

所以我创建了4个变量，如下所示：

  1. private var thisWeekStart: Long = 0
  2. private var thisWeekEnd: Long = 0
  3. private var lastWeekStart: Long = 0
  4. private var lastWeekEnd: Long = 0

我尝试像下面这样赋值：

  1. var cal = Calendar.getInstance()
  2. cal.time = Date()
  3. thisWeekEnd = cal.timeInMillis
  5. // 本周开始
  6. cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY)
  7. thisWeekStart = cal.timeInMillis
  9. cal.add(Calendar.DAY_OF_WEEK, -7)
  10. lastWeekStart = cal.timeInMillis
  12. cal.add(Calendar.DAY_OF_WEEK, 6)
  13. lastWeekEnd = cal.timeInMillis

但它返回的是毫秒，而不是yyyy-MM-dd格式。而且我不确定清除日历的方法是否正确。最重要的是，我无法通过上述方法获取上周的结束日期。

有没有更好的方法来获取本周和上周的开始和结束日期？

英文:

I need to get this week startdate like 2023-02-20 and last week startdate and end date.

startdate will be monday.

so I create 4 variables like below.

  1. private var thisWeekStart : Long = 0
  2.     private var thisWeekEnd : Long = 0
  3.     private var lastWeekStart : Long = 0
  4.     private var lastWeekEnd : Long = 0

And I tried to assign something like below..

  1. var cal = Calendar.getInstance()
  2.         cal.time = Date()
  3.         thisWeekEnd = cal.timeInMillis
  5.         // 이번주 시작
  6.         cal.get(Calendar.DAY_OF_WEEK)
  7.         thisWeekStart = cal.timeInMillis
  9.         cal.add(Calendar.DAY_OF_WEEK, -1)
  10.         lastWeekStart = cal.timeInMillis
  12.         cal.clear()
  13.         cal.set(Calendar.DAY_OF_WEEK, -1)
  14.         lastWeekStart = cal.timeInMillis

But it throws milliseconds not like yyyy-MM-dd format.

And I'm not sure is that correct way of keep clearing calendar like above.

Most of all, I can't get last week's end date with above way.

Is there any good way to get this weed and last week start, end date?

答案1

得分: 1

  1. // tl;dr
  3. 使用 *java.time*。
  5. (使用Java语法而不是Kotlin。)
英文:

tl;dr

Use java.time.

(In Java syntax rather than Kotlin.)

  1. LocalDate                                    // Represent a date-only value.
  2. .now( ZoneId.of( "Asia/Seoul" ) )            // Get the current date as seen in a particular time zone.
  3. .with( 
  4.     TemporalAdjusters.previousOrSame( DayOfWeek.MONDAY ) 
  5. )                                            // Returns another LocalDate. 
  6. .atStartOfDay( ZoneId.of( "Asia/Seoul" ) )   // Determine the first moment of the day on that date in that time zone.
  7. .toInstant()                                 // Convert to UTC. Same moment, same point on the timeline.
  8. .toEpochMilli()                              // Extract a count of milliseconds since 1970-01-01T00:00Z.

Avoid legacy classes

The legacy date-time classes are terrible, deeply flawed in their design. They were supplanted years ago by the modern java.time classes built into Java 8 and later.

An implementation is built into Android 26+. For earlier Android, the latest tooling makes most of the java.time functionality available via API desugaring.

java.time

LocalDate

> need to get this week startdate like 2023-02-20

Use the LocalDate class to represent a date only without a time-of-day and without an offset or time zone.

Using Java syntax (I've not yet learned Kotlin):

  1. LocalDate today = LocalDate.now() ;

Generally best to be explicit about the time zone used to determine the current date.

  1. ZoneId zoneId = ZoneId.of( "Asia/Seoul" ) ; // Or ZoneId.systemDefault(). 
  2. LocalDate today = LocalDate.now() ;

TemporalAdjuster

Use a TemporalAdjuster to move to another day of week. Note the DayOfWeek enum, defining an object for each day of week.

  1. LocalDate previousOrSameMonday = today.with( TemporalAdjusters.previousOrSame( DayOfWeek.MONDAY ) ) ;

To get the following Sunday, add 6 days.

  1. LocalDate sameOrNextSunday = previousOrSameMonday.plusDays( 6 ) ;

But… A span of time is usually better defined using the Half-Open approach. In Half-Open, the beginning is inclusive while the ending is exclusive. So a week starts on a Monday, running up to, but not including, the following Monday.

  1. LocalDate startNextWeek = previousOrSameMonday.plusWeeks( 1 ) ;

Count from epoch

Apparently you want a count of milliseconds from an epoch reference date. I will assume your epoch reference is the first moment of 1970 as seen in UTC, 1970-01-01T00:00Z.

ZonedDateTime

To do this, we need to get the first moment of the day on that date as seen in a particular time zone.

Do not assume the day starts at 00:00. Some days on some dates in some zones start at another time-of-day such as 01:00. Let java.time determine the first moment of the day.

  1. ZonedDateTime zdtStart = previousOrSameMonday.atStartOfDay( zoneId ) ;

Instant

Extract an Instant, the same moment but as seen with an offset from UTC of zero hours-minutes-seconds.

  1. Instant instant = zdtStart.toInstant() ;

From the Instant extract a count from epoch.

  1. long start = instant.toEpochMilli() ;
  2. long end = startNextWeek.atStartOfDay( zoneId ).toInstant().toEpochMilli() ;

Compare

See if a moment lies within that week.

  1. long now = Instant.now().toMilli() ;
  2. if ( 
  3.    ( ! now < start )
  4.     &&
  5.    ( now < end )
  6. ) { … }

答案2

得分: 0

  1. fun getStartAndEndDayByToday(today: Calendar): ArrayList<String> {
  2.     val startAndEndDayArray = ArrayList<String>()
  3.     // 获取今天是本周的星期几
  4.     val todayWeekDay = today.get(Calendar.DAY_OF_WEEK)
  5.     // 下面可以获取本周的开始日期；根据本地时区的不同，它会变化
  6.     today.add(Calendar.DAY_OF_MONTH, 1 - todayWeekDay)
  7.     val calStartDayOfWeek = today.time
  8.     // 下面可以获取本周的结束日期；根据本地时区的不同，它会变化
  9.     today.add(Calendar.DAY_OF_MONTH, 6)
  10.     val calEndDayOfWeek = today.time
  11.     // 在这里，您可以使用SimpleDateFormat设置日期格式
  12.     val sdfStartDayOfWeek = SimpleDateFormat("yyyy-MM-dd")
  13.     val sdfEndDayOfWeek = SimpleDateFormat("yyyy-MM-dd")
  14.     // 将开始日期和结束日期添加到数组中
  15.     startAndEndDayArray.add(sdfStartDayOfWeek.format(calStartDayOfWeek))
  16.     startAndEndDayArray.add(sdfEndDayOfWeek.format(calEndDayOfWeek))
  17.     return startAndEndDayArray
  18. }

希望这对您有帮助！

英文: 
  1. fun getStartAndEndDayByToday(today: Calendar): ArrayList&lt;String&gt; {
  2.     val startAndEndDayArray = ArrayList&lt;String&gt;()
  3.     // Get the day of this week today
  4.     val todayWeekDay = today.get(Calendar.DAY_OF_WEEK)
  5.     // Below you can get the start day of week; it would be changeable according to local time zone
  6.     today.add(Calendar.DAY_OF_MONTH, 1 - todayWeekDay)
  7.     val calStartDayOfWeek = today.time
  8.     // Below you can get the end day of week; it would be changeable according to local time zone
  9.     today.add(Calendar.DAY_OF_MONTH, 6)
  10.     val calEndDayOfWeek = today.time
  11.     // Here you can set the date format by using SimpleDateFormat
  12.     val sdfStartDayOfWeek = SimpleDateFormat(&quot;yyyy-MM-dd&quot;)
  13.     val sdfEndDayOfWeek = SimpleDateFormat(&quot;yyyy-MM-dd&quot;)
  14.     // Make the array with start date and end date
  15.     startAndEndDayArray.add(sdfStartDayOfWeek.format(calStartDayOfWeek))
  16.     startAndEndDayArray.add(sdfEndDayOfWeek.format(calEndDayOfWeek))
  17.     return startAndEndDayArray
  18. }

Hope this would help!

答案3

得分: 0

以下是翻译好的部分：

  1. 首先，我们定义我们期望的输出格式。在这种情况下，我们将使用`yyyy-MM-dd`格式。在下一步中，我们将当前日期保存在一个变量中。在第三行，我们定义了我们正在使用的时区（我在测试中使用了`Europe/Berlin`，因为我在德国）。
  3. 在接下来的步骤中，我们为每个期望的日期创建了`Calendar`实例，并根据我们的需求操作日期。
  5. 重要提示：只有在您的一周开始日期不是星期日时，您才需要添加`firstDayOfWeek = Calendar.MONDAY`这一行。
  7.     val dateFormat = SimpleDateFormat("yyyy-MM-dd")
  8.     val today = Calendar.getInstance()
  9.     val timeZone = TimeZone.getTimeZone("Europe/Berlin")
  11.     val startOfWeek = Calendar.getInstance(timeZone).apply {
  12.         firstDayOfWeek = Calendar.MONDAY
  13.         set(Calendar.DAY_OF_WEEK, Calendar.MONDAY)
  14.     }.time
  16.     val endOfWeek = Calendar.getInstance(timeZone).apply {
  17.         firstDayOfWeek = Calendar.MONDAY
  18.         set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY)
  19.     }.time
  21.     val startOfLastWeek = Calendar.getInstance(timeZone).apply {
  22.         firstDayOfWeek = Calendar.MONDAY
  23.         set(Calendar.WEEK_OF_YEAR, today.get(Calendar.WEEK_OF_YEAR) - 1)
  24.         set(Calendar.DAY_OF_WEEK, Calendar.MONDAY)
  25.     }.time
  27.     val endOfLastWeek = Calendar.getInstance(timeZone).apply {
  28.         firstDayOfWeek = Calendar.MONDAY
  29.         set(Calendar.WEEK_OF_YEAR, today.get(Calendar.WEEK_OF_YEAR) - 1)
  30.         set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY)
  31.     }.time
  33.     val startOfWeekAsString = dateFormat.format(startOfWeek)
  34.     val endOfWeekAsString = dateFormat.format(endOfWeek)
  35.     val startOfLastWeekAsString = dateFormat.format(startOfLastWeek)
  36.     val endOfLastWeekAsString = dateFormat.format(endOfLastWeek)
  38.     println("Start of week: $startOfWeekAsString")
  39.     println("End of week: $endOfWeekAsString")
  40.     println("Start of last week: $startOfLastWeekAsString")
  41.     println("End of last week: $endOfLastWeekAsString")

期望的输出：

  1. Start of week: 2023-02-13
  2. End of week: 2023-02-19
  3. Start of last week: 2023-02-06
  4. End of last week: 2023-02-12
英文:

At first, we define our desired output format. In this case we will use yyyy-MM-dd. In the next step we save the current date in a variable. In the third line we define timezone in which we are working (I used Europe/Berlin for testing purposes, bacause I'm in germany).

In the next steps we create Calendar instance for each desired date and manipulate the date to our needs.

Important: You have to add the line firstDayOfWeek = Calendar.MONDAY only if your week starts at another date than Sunday.

  1. val dateFormat = SimpleDateFormat(&quot;yyyy-MM-dd&quot;)
  2. val today = Calendar.getInstance()
  3. val timeZone = TimeZone.getTimeZone(&quot;Europe/Berlin&quot;)
  5. val startOfWeek = Calendar.getInstance(timeZone).apply {
  6.     firstDayOfWeek = Calendar.MONDAY
  7.     set(Calendar.DAY_OF_WEEK, Calendar.MONDAY)
  8. }.time
  10. val endOfWeek = Calendar.getInstance(timeZone).apply {
  11.     firstDayOfWeek = Calendar.MONDAY
  12.     set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY)
  13. }.time
  15. val startOfLastWeek = Calendar.getInstance(timeZone).apply {
  16.     firstDayOfWeek = Calendar.MONDAY
  17.     set(Calendar.WEEK_OF_YEAR, today.get(Calendar.WEEK_OF_YEAR) - 1)
  18.     set(Calendar.DAY_OF_WEEK, Calendar.MONDAY)
  19. }.time
  21. val endOfLastWeek = Calendar.getInstance(timeZone).apply {
  22.     firstDayOfWeek = Calendar.MONDAY
  23.     set(Calendar.WEEK_OF_YEAR, today.get(Calendar.WEEK_OF_YEAR) - 1)
  24.     set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY)
  25. }.time
  27. val startOfWeekAsString = dateFormat.format(startOfWeek)
  28. val endOfWeekAsString = dateFormat.format(endOfWeek)
  29. val startOfLastWeekAsString = dateFormat.format(startOfLastWeek)
  30. val endOfLastWeekAsString = dateFormat.format(endOfLastWeek)
  32. println(&quot;Start of week: $startOfWeekAsString&quot;)
  33. println(&quot;End of week: $endOfWeekAsString&quot;)
  34. println(&quot;Start of last week: $startOfLastWeekAsString&quot;)
  35. println(&quot;End of last week: $endOfLastWeekAsString&quot;)

Expected output:

  1. Start of week: 2023-02-13
  2. End of week: 2023-02-19
  3. Start of last week: 2023-02-06
  4. End of last week: 2023-02-12

huangapple
  • 本文由 发表于 2023年2月19日 23:50:26
  • 转载请务必保留本文链接：https://go.coder-hub.com/75501348.html
  • android
  • date
  • dayofweek
  • java.util.calendar
  • kotlin
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