Articolo
11/18/2011

JapaneseCalendar Class

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Represents the Japanese calendar.

Inheritance Hierarchy

System.Object
System.Globalization.Calendar
System.Globalization.JapaneseCalendar

Namespace: System.Globalization
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
<ComVisibleAttribute(True)> _
Public Class JapaneseCalendar _
    Inherits Calendar

[ComVisibleAttribute(true)]
public class JapaneseCalendar : Calendar

The JapaneseCalendar type exposes the following members.

Constructors

	Name	Description
	JapaneseCalendar	Initializes a new instance of the JapaneseCalendar class.

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Properties

	Name	Description
	Eras	Gets the list of eras in the JapaneseCalendar. (Overrides Calendar.Eras.)
	IsReadOnly	Gets a value indicating whether this Calendar object is read-only. (Inherited from Calendar.)
	MaxSupportedDateTime	Gets the latest date and time supported by the JapaneseCalendar class. (Overrides Calendar.MaxSupportedDateTime.)
	MinSupportedDateTime	Gets the earliest date and time supported by the JapaneseCalendar class. (Overrides Calendar.MinSupportedDateTime.)
	TwoDigitYearMax	Gets or sets the last year of a 100-year range that can be represented by a 2-digit year. (Overrides Calendar.TwoDigitYearMax.)

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Methods

	Name	Description
	AddDays	Returns a DateTime that is the specified number of days away from the specified DateTime. (Inherited from Calendar.)
	AddHours	Returns a DateTime that is the specified number of hours away from the specified DateTime. (Inherited from Calendar.)
	AddMilliseconds	Returns a DateTime that is the specified number of milliseconds away from the specified DateTime. (Inherited from Calendar.)
	AddMinutes	Returns a DateTime that is the specified number of minutes away from the specified DateTime. (Inherited from Calendar.)
	AddMonths	Returns a DateTime that is the specified number of months away from the specified DateTime. (Overrides Calendar.AddMonths(DateTime, Int32).)
	AddSeconds	Returns a DateTime that is the specified number of seconds away from the specified DateTime. (Inherited from Calendar.)
	AddWeeks	Returns a DateTime that is the specified number of weeks away from the specified DateTime. (Inherited from Calendar.)
	AddYears	Returns a DateTime that is the specified number of years away from the specified DateTime. (Overrides Calendar.AddYears(DateTime, Int32).)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetDayOfMonth	Returns the day of the month in the specified DateTime. (Overrides Calendar.GetDayOfMonth(DateTime).)
	GetDayOfWeek	Returns the day of the week in the specified DateTime. (Overrides Calendar.GetDayOfWeek(DateTime).)
	GetDayOfYear	Returns the day of the year in the specified DateTime. (Overrides Calendar.GetDayOfYear(DateTime).)
	GetDaysInMonth(Int32, Int32)	Returns the number of days in the specified month and year of the current era. (Inherited from Calendar.)
	GetDaysInMonth(Int32, Int32, Int32)	Returns the number of days in the specified month in the specified year in the specified era. (Overrides Calendar.GetDaysInMonth(Int32, Int32, Int32).)
	GetDaysInYear(Int32)	Returns the number of days in the specified year of the current era. (Inherited from Calendar.)
	GetDaysInYear(Int32, Int32)	Returns the number of days in the specified year in the specified era. (Overrides Calendar.GetDaysInYear(Int32, Int32).)
	GetEra	Returns the era of a specified DateTime value. (Overrides Calendar.GetEra(DateTime).)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetHour	Returns the hours value in the specified DateTime. (Inherited from Calendar.)
	GetLeapMonth	Calculates the leap month for a specified year and era. (Overrides Calendar.GetLeapMonth(Int32, Int32).)
	GetMilliseconds	Returns the milliseconds value in the specified DateTime. (Inherited from Calendar.)
	GetMinute	Returns the minutes value in the specified DateTime. (Inherited from Calendar.)
	GetMonth	Returns the month in the specified DateTime. (Overrides Calendar.GetMonth(DateTime).)
	GetMonthsInYear(Int32)	Returns the number of months in the specified year in the current era. (Inherited from Calendar.)
	GetMonthsInYear(Int32, Int32)	Returns the number of months in the specified year in the specified era. (Overrides Calendar.GetMonthsInYear(Int32, Int32).)
	GetSecond	Returns the seconds value in the specified DateTime. (Inherited from Calendar.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetWeekOfYear	Returns the week of the year that includes the date in the specified DateTime. (Overrides Calendar.GetWeekOfYear(DateTime, CalendarWeekRule, DayOfWeek).)
	GetYear	Returns the year in the specified DateTime. (Overrides Calendar.GetYear(DateTime).)
	IsLeapDay(Int32, Int32, Int32)	Determines whether the specified date in the current era is a leap day. (Inherited from Calendar.)
	IsLeapDay(Int32, Int32, Int32, Int32)	Determines whether the specified date in the specified era is a leap day. (Overrides Calendar.IsLeapDay(Int32, Int32, Int32, Int32).)
	IsLeapMonth(Int32, Int32)	Determines whether the specified month in the specified year in the current era is a leap month. (Inherited from Calendar.)
	IsLeapMonth(Int32, Int32, Int32)	Determines whether the specified month in the specified year in the specified era is a leap month. (Overrides Calendar.IsLeapMonth(Int32, Int32, Int32).)
	IsLeapYear(Int32)	Determines whether the specified year in the current era is a leap year. (Inherited from Calendar.)
	IsLeapYear(Int32, Int32)	Determines whether the specified year in the specified era is a leap year. (Overrides Calendar.IsLeapYear(Int32, Int32).)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ToDateTime(Int32, Int32, Int32, Int32, Int32, Int32, Int32)	Returns a DateTime that is set to the specified date and time in the current era. (Inherited from Calendar.)
	ToDateTime(Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32)	Returns a DateTime that is set to the specified date and time in the specified era. (Overrides Calendar.ToDateTime(Int32, Int32, Int32, Int32, Int32, Int32, Int32, Int32).)
	ToFourDigitYear	Converts the specified year to a four-digit year by using the TwoDigitYearMax property to determine the appropriate century. (Overrides Calendar.ToFourDigitYear(Int32).)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Remarks

The Japanese calendar, which is also known as the Wareki calendar, works exactly like the Gregorian calendar, except that the year and era are different.

The Japanese calendar recognizes one era for every emperor's reign. The current era is the Heisei era, which began in the Gregorian calendar year 1989. The era name is typically displayed before the year. For example, the Gregorian calendar year 2001 is the Japanese calendar year Heisei 13. Note that the first year of an era is called "Gannen." Therefore, the Gregorian calendar year 1989 was the Japanese calendar year Heisei Gannen.

This class assigns numbers to the eras as follows:

GetEra value	Era Name	Era Abbreviation	Gregorian Dates
4	平成 (Heisei)	平 (H, h)	January 8, 1989 to present
3	昭和 (Showa)	昭 (S, s)	December 25, 1926 to January 7, 1989
2	大正 (Taisho)	大 (T, t)	July 30, 1912 to December 24, 1926
1	明治 (Meiji)	明 (M, m)	January 1, 1868 to July 29, 1912

This class handles only dates from the first day of the first month in the year Meiji 1 (January 1, 1868 of the Gregorian calendar). Although the Japanese calendar was switched from a lunar calendar to a solar calendar in the year Meiji 6 (1873 of the Gregorian calendar), this implementation is based on the solar calendar only.

Leap years in the Japanese calendar correspond to the same leap years in the Gregorian calendar. A leap year in the Gregorian calendar is defined as a Gregorian year that is evenly divisible by four, except if it is divisible by 100. However, Gregorian years that are divisible by 400 are leap years. A common year has 365 days and a leap year has 366 days.

The Japanese calendar has 12 months with 28 to 31 days each:

GetMonth value	Month	English	Days in common years	Days in leap years
1	1月 (Ichigatsu)	January	31	31
2	2月 (Nigatsu)	February	28	29
3	3月 (Sangatsu)	March	31	31
4	4月 (Shigatsu)	April	30	30
5	5月 (Gogatsu)	May	31	31
6	6月 (Rokugatsu)	June	30	30
7	7月 (Shichigatsu)	July	31	31
8	8月 (Hachigatsu)	August	31	31
9	9月 (Kugatsu)	September	30	30
10	10月 (Juugatsu)	October	31	31
11	11月 (Juuichigatsu)	November	30	30
12	12月 (Juunigatsu)	December	31	31

Nigatsu, which is equivalent to the Gregorian calendar month of February, has 29 days during leap years and 28 during common years.

The date January 1, 2001 A.D. in the Gregorian calendar is equivalent to the first day of Ichigatsu in the year Heisei 13 in the Japanese calendar.

If the application is using the JapaneseCalendar class, DateTime.Parse recognizes the era abbreviations in front of the year. The abbreviation is either the single-character case-insensitive Latin alphabet abbreviation or the single-character Kanji abbreviation.

Each CultureInfo object supports a set of calendars. The CultureInfo.Calendar property returns the default calendar for the culture, and the CultureInfo.OptionalCalendars property returns an array containing all the calendars supported by the culture. To change the calendar used by a CultureInfo object, the application should set the Calendar property of CultureInfo.DateTimeFormat to a new Calendar object if the new calendar is one of the culture's optional calendars. The following example shows how to change the calendar for the ja-JP culture to the Japanese calendar.

' Change the calendar used by a Japanese CultureInfo object from Gregorian to Japanese. 
Dim japanCulture As New CultureInfo("ja-JP")
Dim originalCalendar As Calendar = japanCulture.Calendar
Dim message As String = Nothing

' Confirm that the default calendar is not the Japanese calendar.
If originalCalendar.ToString <> "System.Globalization.JapaneseCalendar" Then
   ' Check whether the culture supports the Japanese calendar.
   Dim supported As Boolean = False
   For Each supportedCal As Calendar In japanCulture.OptionalCalendars
      If supportedCal.ToString = "System.Globalization.JapaneseCalendar" Then
         supported = True            
         japanCulture.DateTimeFormat.Calendar = supportedCal
         message = String.Format("Changed the current calendar for the {0} culture from {1} to {2}.", _
                                 japanCulture.ToString(), _
                                 originalCalendar.ToString.Replace("System.Globalization.", ""), _
                                 supportedCal.ToString.Replace("System.Globalization.", ""))                                 
         Exit For
      End If
      If Not supported Then message = "The Japanese calendar is not supported."
   Next        
Else
   message = String.Format("Japanese is the default calendar for the {0} culture.", _
                           japanCulture.ToString())
End If
outputBlock.Text += message + vbCrLf
' The example displays the following output:
'   Changed the current calendar for the ja-JP culture from GregorianCalendar to JapaneseCalendar.

// Change the calendar used by a Japanese CultureInfo object from Gregorian to Japanese. 
CultureInfo japanCulture = new CultureInfo("ja-JP");
Calendar originalCalendar = japanCulture.Calendar;
string message = null;

// Confirm that the default calendar is not the Japanese calendar.
if (originalCalendar.ToString() != "System.Globalization.JapaneseCalendar")
{
   // Check whether the culture supports the Japanese calendar.
   bool supported = false;
   foreach (Calendar supportedCal in japanCulture.OptionalCalendars)
   {
      if (supportedCal.ToString() == "System.Globalization.JapaneseCalendar")
      {
         supported = true;            
         japanCulture.DateTimeFormat.Calendar = supportedCal;
         message = String.Format("Changed the current calendar for the {0} culture from {1} to {2}.",
                                 japanCulture.ToString(),
                                 originalCalendar.ToString().Replace("System.Globalization.", ""),
                                 supportedCal.ToString().Replace("System.Globalization.", ""));                                 
         break;
      }
   }
   if (! supported) message = "The Japanese calendar is not supported.";
}        
else
{
   message = String.Format("Japanese is the default calendar for the {0} culture.",
                           japanCulture.ToString());
}
outputBlock.Text += message + "\n";
// The example displays the following output:
//   Changed the current calendar for the ja-JP culture from GregorianCalendar to JapaneseCalendar.

Platform Notes

Silverlight for Windows Phone

This type is present but is not currently supported on Windows Phone.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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