Calendar

public abstract class Calendar
extends Object implements Serializable, Cloneable, Comparable<Calendar>

java.lang.Object
   ↳ android.icu.util.Calendar

[icu enhancement] ICU's replacement for Calendar. Methods, fields, and other functionality specific to ICU are labeled '[icu]'.

Calendar is an abstract base class for converting between a Date object and a set of integer fields such as YEAR, MONTH, DAY, HOUR, and so on. (A Date object represents a specific instant in time with millisecond precision. See Date for information about the Date class.)

Subclasses of Calendar interpret a Date according to the rules of a specific calendar system. ICU4J contains several subclasses implementing different international calendar systems.

Like other locale-sensitive classes, Calendar provides a class method, getInstance, for getting a generally useful object of this type. Calendar's getInstance method returns a calendar of a type appropriate to the locale, whose time fields have been initialized with the current date and time: 

Calendar rightNow = Calendar.getInstance()

When a ULocale is used by getInstance, its 'calendar' tag and value are retrieved if present. If a recognized value is supplied, a calendar is provided and configured as appropriate. Currently recognized tags are "buddhist", "chinese", "coptic", "ethiopic", "gregorian", "hebrew", "islamic", "islamic-civil", "japanese", and "roc". For example: 

Calendar cal = Calendar.getInstance(new ULocale("en_US@calendar=japanese"));
will return an instance of JapaneseCalendar (using en_US conventions for minimum days in first week, start day of week, et cetera).

A Calendar object can produce all the time field values needed to implement the date-time formatting for a particular language and calendar style (for example, Japanese-Gregorian, Japanese-Traditional). Calendar defines the range of values returned by certain fields, as well as their meaning. For example, the first month of the year has value MONTH == JANUARY for all calendars. Other values are defined by the concrete subclass, such as ERA and YEAR. See individual field documentation and subclass documentation for details.

When a Calendar is lenient, it accepts a wider range of field values than it produces. For example, a lenient GregorianCalendar interprets MONTH == JANUARY, DAY_OF_MONTH == 32 as February 1. A non-lenient GregorianCalendar throws an exception when given out-of-range field settings. When calendars recompute field values for return by get(), they normalize them. For example, a GregorianCalendar always produces DAY_OF_MONTH values between 1 and the length of the month.

Calendar defines a locale-specific seven day week using two parameters: the first day of the week and the minimal days in first week (from 1 to 7). These numbers are taken from the locale resource data when a Calendar is constructed. They may also be specified explicitly through the API.

When setting or getting the WEEK_OF_MONTH or WEEK_OF_YEAR fields, Calendar must determine the first week of the month or year as a reference point. The first week of a month or year is defined as the earliest seven day period beginning on getFirstDayOfWeek() and containing at least getMinimalDaysInFirstWeek() days of that month or year. Weeks numbered ..., -1, 0 precede the first week; weeks numbered 2, 3,... follow it. Note that the normalized numbering returned by get() may be different. For example, a specific Calendar subclass may designate the week before week 1 of a year as week n of the previous year.

When computing a Date from time fields, some special circumstances may arise: there may be insufficient information to compute the Date (such as only year and month but no day in the month), there may be inconsistent information (such as "Tuesday, July 15, 1996" -- July 15, 1996 is actually a Monday), or the input time might be ambiguous because of time zone transition.

Insufficient information. The calendar will use default information to specify the missing fields. This may vary by calendar; for the Gregorian calendar, the default for a field is the same as that of the start of the epoch: i.e., YEAR = 1970, MONTH = JANUARY, DATE = 1, etc.

Inconsistent information. If fields conflict, the calendar will give preference to fields set more recently. For example, when determining the day, the calendar will look for one of the following combinations of fields. The most recent combination, as determined by the most recently set single field, will be used. 

 MONTH + DAY_OF_MONTH
 MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
 MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
 DAY_OF_YEAR
 DAY_OF_WEEK + WEEK_OF_YEAR
For the time of day: 
 HOUR_OF_DAY
 AM_PM + HOUR

Ambiguous Wall Clock Time. When time offset from UTC has changed, it produces an ambiguous time slot around the transition. For example, many US locations observe daylight saving time. On the date switching to daylight saving time in US, wall clock time jumps from 12:59 AM (standard) to 2:00 AM (daylight). Therefore, wall clock time from 1:00 AM to 1:59 AM do not exist on the date. When the input wall time fall into this missing time slot, the ICU Calendar resolves the time using the UTC offset before the transition by default. In this example, 1:30 AM is interpreted as 1:30 AM standard time (non-exist), so the final result will be 2:30 AM daylight time.

On the date switching back to standard time, wall clock time is moved back one hour at 2:00 AM. So wall clock time from 1:00 AM to 1:59 AM occur twice. In this case, the ICU Calendar resolves the time using the UTC offset after the transition by default. For example, 1:30 AM on the date is resolved as 1:30 AM standard time.

Ambiguous wall clock time resolution behaviors can be customized by Calendar APIs setRepeatedWallTimeOption(int) and setSkippedWallTimeOption(int). These methods are available in ICU 49 or later versions.

Note: for some non-Gregorian calendars, different fields may be necessary for complete disambiguation. For example, a full specification of the historial Arabic astronomical calendar requires year, month, day-of-month and day-of-week in some cases.

Note: There are certain possible ambiguities in interpretation of certain singular times, which are resolved in the following ways:

  1. 24:00:00 "belongs" to the following day. That is, 23:59 on Dec 31, 1969 < 24:00 on Jan 1, 1970 < 24:01:00 on Jan 1, 1970
  2. Although historically not precise, midnight also belongs to "am", and noon belongs to "pm", so on the same day, 12:00 am (midnight) < 12:01 am, and 12:00 pm (noon) < 12:01 pm

The date or time format strings are not part of the definition of a calendar, as those must be modifiable or overridable by the user at runtime. Use DateFormat to format dates.

Field manipulation methods

Calendar fields can be changed using three methods: set(), add(), and roll().

set(f, value) changes field f to value. In addition, it sets an internal member variable to indicate that field f has been changed. Although field f is changed immediately, the calendar's milliseconds is not recomputed until the next call to get(), getTime(), or getTimeInMillis() is made. Thus, multiple calls to set() do not trigger multiple, unnecessary computations. As a result of changing a field using set(), other fields may also change, depending on the field, the field value, and the calendar system. In addition, get(f) will not necessarily return value after the fields have been recomputed. The specifics are determined by the concrete calendar class.

Example: Consider a GregorianCalendar originally set to August 31, 1999. Calling set(Calendar.MONTH, Calendar.SEPTEMBER) sets the calendar to September 31, 1999. This is a temporary internal representation that resolves to October 1, 1999 if getTime()is then called. However, a call to set(Calendar.DAY_OF_MONTH, 30) before the call to getTime() sets the calendar to September 30, 1999, since no recomputation occurs after set() itself.

add(f, delta) adds delta to field f. This is equivalent to calling set(f, get(f) + delta) with two adjustments:

Add rule 1. The value of field f after the call minus the value of field f before the call is delta, modulo any overflow that has occurred in field f. Overflow occurs when a field value exceeds its range and, as a result, the next larger field is incremented or decremented and the field value is adjusted back into its range.

Add rule 2. If a smaller field is expected to be invariant, but   it is impossible for it to be equal to its prior value because of changes in its minimum or maximum after field f is changed, then its value is adjusted to be as close as possible to its expected value. A smaller field represents a smaller unit of time. HOUR is a smaller field than DAY_OF_MONTH. No adjustment is made to smaller fields that are not expected to be invariant. The calendar system determines what fields are expected to be invariant.

In addition, unlike set(), add() forces an immediate recomputation of the calendar's milliseconds and all fields.

Example: Consider a GregorianCalendar originally set to August 31, 1999. Calling add(Calendar.MONTH, 13) sets the calendar to September 30, 2000. Add rule 1 sets the MONTH field to September, since adding 13 months to August gives September of the next year. Since DAY_OF_MONTH cannot be 31 in September in a GregorianCalendar, add rule 2 sets the DAY_OF_MONTH to 30, the closest possible value. Although it is a smaller field, DAY_OF_WEEK is not adjusted by rule 2, since it is expected to change when the month changes in a GregorianCalendar.

roll(f, delta) adds delta to field f without changing larger fields. This is equivalent to calling add(f, delta) with the following adjustment:

Roll rule. Larger fields are unchanged after the call. A larger field represents a larger unit of time. DAY_OF_MONTH is a larger field than HOUR.

Example: Consider a GregorianCalendar originally set to August 31, 1999. Calling roll(Calendar.MONTH, 8) sets the calendar to April 30, 1999. Add rule 1 sets the MONTH field to April. Using a GregorianCalendar, the DAY_OF_MONTH cannot be 31 in the month April. Add rule 2 sets it to the closest possible value, 30. Finally, the roll rule maintains the YEAR field value of 1999.

Example: Consider a GregorianCalendar originally set to Sunday June 6, 1999. Calling roll(Calendar.WEEK_OF_MONTH, -1) sets the calendar to Tuesday June 1, 1999, whereas calling add(Calendar.WEEK_OF_MONTH, -1) sets the calendar to Sunday May 30, 1999. This is because the roll rule imposes an additional constraint: The MONTH must not change when the WEEK_OF_MONTH is rolled. Taken together with add rule 1, the resultant date must be between Tuesday June 1 and Saturday June 5. According to add rule 2, the DAY_OF_WEEK, an invariant when changing the WEEK_OF_MONTH, is set to Tuesday, the closest possible value to Sunday (where Sunday is the first day of the week).

Usage model. To motivate the behavior of add() and roll(), consider a user interface component with increment and decrement buttons for the month, day, and year, and an underlying GregorianCalendar. If the interface reads January 31, 1999 and the user presses the month increment button, what should it read? If the underlying implementation uses set(), it might read March 3, 1999. A better result would be February 28, 1999. Furthermore, if the user presses the month increment button again, it should read March 31, 1999, not March 28, 1999. By saving the original date and using either add() or roll(), depending on whether larger fields should be affected, the user interface can behave as most users will intuitively expect.

Note: You should always use roll and add rather than attempting to perform arithmetic operations directly on the fields of a Calendar. It is quite possible for Calendar subclasses to have fields with non-linear behavior, for example missing months or days during non-leap years. The subclasses' add and roll methods will take this into account, while simple arithmetic manipulations may give invalid results.

Calendar Architecture in ICU4J

Recently the implementation of Calendar has changed significantly in order to better support subclassing. The original Calendar class was designed to support subclassing, but it had only one implemented subclass, GregorianCalendar. With the implementation of several new calendar subclasses, including the BuddhistCalendar, ChineseCalendar, HebrewCalendar, IslamicCalendar, and JapaneseCalendar, the subclassing API has been reworked thoroughly. This section details the new subclassing API and other ways in which android.icu.util.Calendar differs from java.util.Calendar.

Changes

Overview of changes between the classic Calendar architecture and the new architecture.

  • The fields[] array is private now instead of protected. Subclasses must access it using the methods internalSet(int, int) and internalGet(int). Motivation: Subclasses should not directly access data members.
  • The time long word is private now instead of protected. Subclasses may access it using the method internalGetTimeInMillis(), which does not provoke an update. Motivation: Subclasses should not directly access data members.
  • The scope of responsibility of subclasses has been drastically reduced. As much functionality as possible is implemented in the Calendar base class. As a result, it is much easier to subclass Calendar. Motivation: Subclasses should not have to reimplement common code. Certain behaviors are common across calendar systems: The definition and behavior of week-related fields and time fields, the arithmetic (add and roll) behavior of many fields, and the field validation system.
  • The subclassing API has been completely redesigned.
  • The Calendar base class contains some Gregorian calendar algorithmic support that subclasses can use (specifically in handleComputeFields(int)). Subclasses can use the methods getGregorianXxx() to obtain precomputed values. Motivation: This is required by all Calendar subclasses in order to implement consistent time zone behavior, and Gregorian-derived systems can use the already computed data.
  • The FIELD_COUNT constant has been removed. Use getFieldCount(). In addition, framework API has been added to allow subclasses to define additional fields. Motivation: The number of fields is not constant across calendar systems.
  • The range of handled dates has been narrowed from +/- ~300,000,000 years to +/- ~5,000,000 years. In practical terms this should not affect clients. However, it does mean that client code cannot be guaranteed well-behaved results with dates such as Date(Long.MIN_VALUE) or Date(Long.MAX_VALUE). Instead, the Calendar protected constants should be used. Motivation: With the addition of the JULIAN_DAY field, Julian day numbers must be restricted to a 32-bit int. This restricts the overall supported range. Furthermore, restricting the supported range simplifies the computations by removing special case code that was used to accommodate arithmetic overflow at millis near Long.MIN_VALUE and Long.MAX_VALUE.
  • New fields are implemented: JULIAN_DAY defines single-field specification of the date. MILLISECONDS_IN_DAY defines a single-field specification of the wall time. DOW_LOCAL and YEAR_WOY implement localized day-of-week and week-of-year behavior.
  • Subclasses can access protected millisecond constants defined in Calendar.
  • New API has been added to support calendar-specific subclasses of DateFormat.
  • Several subclasses have been implemented, representing various international calendar systems.

Subclass API

The original Calendar API was based on the experience of implementing a only a single subclass, GregorianCalendar. As a result, all of the subclassing kinks had not been worked out. The new subclassing API has been refined based on several implemented subclasses. This includes methods that must be overridden and methods for subclasses to call. Subclasses no longer have direct access to fields and stamp. Instead, they have new API to access these. Subclasses are able to allocate the fields array through a protected framework method; this allows subclasses to specify additional fields.

More functionality has been moved into the base class. The base class now contains much of the computational machinery to support the Gregorian calendar. This is based on two things: (1) Many calendars are based on the Gregorian calendar (such as the Buddhist and Japanese imperial calendars). (2) All calendars require basic Gregorian support in order to handle timezone computations.

Common computations have been moved into Calendar. Subclasses no longer compute the week related fields and the time related fields. These are commonly handled for all calendars by the base class.

Subclass computation of time => fields

The ERA, YEAR, EXTENDED_YEAR, MONTH, DAY_OF_MONTH, and DAY_OF_YEAR fields are computed by the subclass, based on the Julian day. All other fields are computed by Calendar.

  • Subclasses should implement handleComputeFields(int) to compute the ERA, YEAR, EXTENDED_YEAR, MONTH, DAY_OF_MONTH, and DAY_OF_YEAR fields, based on the value of the JULIAN_DAY field. If there are calendar-specific fields not defined by Calendar, they must also be computed. These are the only fields that the subclass should compute. All other fields are computed by the base class, so time and week fields behave in a consistent way across all calendars. The default version of this method in Calendar implements a proleptic Gregorian calendar. Within this method, subclasses may call getGregorianXxx() to obtain the Gregorian calendar month, day of month, and extended year for the given date.

Subclass computation of fields => time

The interpretation of most field values is handled entirely by Calendar. Calendar determines which fields are set, which are not, which are set more recently, and so on. In addition, Calendar handles the computation of the time from the time fields and handles the week-related fields. The only thing the subclass must do is determine the extended year, based on the year fields, and then, given an extended year and a month, it must return a Julian day number.

  • Subclasses should implement handleGetExtendedYear() to return the extended year for this calendar system, based on the YEAR, EXTENDED_YEAR, and any fields that the calendar system uses that are larger than a year, such as ERA.
  • Subclasses should implement handleComputeMonthStart(int, int, boolean) to return the Julian day number associated with a month and extended year. This is the Julian day number of the day before the first day of the month. The month number is zero-based. This computation should not depend on any field values.

Other methods

  • Subclasses should implement handleGetMonthLength(int, int) to return the number of days in a given month of a given extended year. The month number, as always, is zero-based.
  • Subclasses should implement handleGetYearLength(int) to return the number of days in the given extended year. This method is used by computeWeekFields to compute the WEEK_OF_YEAR and YEAR_WOY fields.
  • Subclasses should implement handleGetLimit(int, int) to return the protected values of a field, depending on the value of limitType. This method only needs to handle the fields ERA, YEAR, MONTH, WEEK_OF_YEAR, WEEK_OF_MONTH, DAY_OF_MONTH, DAY_OF_YEAR, DAY_OF_WEEK_IN_MONTH, YEAR_WOY, and EXTENDED_YEAR. Other fields are invariant (with respect to calendar system) and are handled by the base class.
  • Optionally, subclasses may override validateField(int) to check any subclass-specific fields. If the field's value is out of range, the method should throw an IllegalArgumentException. The method may call super.validateField(field) to handle fields in a generic way, that is, to compare them to the range getMinimum(field)..getMaximum(field).
  • Optionally, subclasses may override handleCreateFields() to create an int[] array large enough to hold the calendar's fields. This is only necessary if the calendar defines additional fields beyond those defined by Calendar. The length of the result must be be between the base and maximum field counts.
  • Optionally, subclasses may override handleGetDateFormat(String, ULocale) to create a DateFormat appropriate to this calendar. This is only required if a calendar subclass redefines the use of a field (for example, changes the ERA field from a symbolic field to a numeric one) or defines an additional field.
  • Optionally, subclasses may override roll and add to handle fields that are discontinuous. For example, in the Hebrew calendar the month "Adar I" only occurs in leap years; in other years the calendar jumps from Shevat (month #4) to Adar (month #6). The HebrewCalendar.add and HebrewCalendar.roll methods take this into account, so that adding 1 month to Shevat gives the proper result (Adar) in a non-leap year. The protected utility method pinField is often useful when implementing these two methods.

Normalized behavior

The behavior of certain fields has been made consistent across all calendar systems and implemented in Calendar.

  • Time is normalized. Even though some calendar systems transition between days at sunset or at other times, all ICU4J calendars transition between days at local zone midnight. This allows ICU4J to centralize the time computations in Calendar and to maintain basic correspondences between calendar systems. Affected fields: AM_PM, HOUR, HOUR_OF_DAY, MINUTE, SECOND, MILLISECOND, ZONE_OFFSET, and DST_OFFSET.
  • DST behavior is normalized. Daylight savings time behavior is computed the same for all calendar systems, and depends on the value of several GregorianCalendar fields: the YEAR, MONTH, and DAY_OF_MONTH. As a result, Calendar always computes these fields, even for non-Gregorian calendar systems. These fields are available to subclasses.
  • Weeks are normalized. Although locales define the week differently, in terms of the day on which it starts, and the designation of week number one of a month or year, they all use a common mechanism. Furthermore, the day of the week has a simple and consistent definition throughout history. For example, although the Gregorian calendar introduced a discontinuity when first instituted, the day of week was not disrupted. For this reason, the fields DAY_OF_WEEK, WEEK_OF_YEAR, WEEK_OF_MONTH, DAY_OF_WEEK_IN_MONTH, DOW_LOCAL, YEAR_WOY are all computed in a consistent way in the base class, based on the EXTENDED_YEAR, DAY_OF_YEAR, MONTH, and DAY_OF_MONTH, which are computed by the subclass.

Supported range

The allowable range of Calendar has been narrowed. GregorianCalendar used to attempt to support the range of dates with millisecond values from Long.MIN_VALUE to Long.MAX_VALUE. This introduced awkward constructions (hacks) which slowed down performance. It also introduced non-uniform behavior at the boundaries. The new Calendar protocol specifies the maximum range of supportable dates as those having Julian day numbers of -0x7F000000 to +0x7F000000. This corresponds to years from ~5,800,000 BCE to ~5,800,000 CE. Programmers should use the protected constants in Calendar to specify an extremely early or extremely late date.

General notes

  • Calendars implementations are proleptic. For example, even though the Gregorian calendar was not instituted until the 16th century, the GregorianCalendar class supports dates before the historical onset of the calendar by extending the calendar system backward in time. Similarly, the HebrewCalendar extends backward before the start of its epoch into zero and negative years. Subclasses do not throw exceptions because a date precedes the historical start of a calendar system. Instead, they implement handleGetLimit(int, int) to return appropriate limits on YEAR, ERA, etc. fields. Then, if the calendar is set to not be lenient, out-of-range field values will trigger an exception.
  • Calendar system subclasses compute a extended year. This differs from the YEAR field in that it ranges over all integer values, including zero and negative values, and it encapsulates the information of the YEAR field and all larger fields. Thus, for the Gregorian calendar, the EXTENDED_YEAR is computed as ERA==AD ? YEAR : 1-YEAR. Another example is the Mayan long count, which has years (KUN) and nested cycles of years (KATUN and BAKTUN). The Mayan EXTENDED_YEAR is computed as TUN + 20 * (KATUN + 20 * BAKTUN). The Calendar base class uses the EXTENDED_YEAR field to compute the week-related fields.

Summary

Nested classes

class Calendar.WeekData

Simple, immutable struct-like class for access to the CLDR week data. 

Constants

int AM

Value of the AM_PM field indicating the period of the day from midnight to just before noon.

int AM_PM

Field number for get and set indicating whether the HOUR is before or after noon.

int APRIL

Value of the MONTH field indicating the fourth month of the year.

int AUGUST

Value of the MONTH field indicating the eighth month of the year.

int DATE

Field number for get and set indicating the day of the month.

int DAY_OF_MONTH

Field number for get and set indicating the day of the month.

int DAY_OF_WEEK

Field number for get and set indicating the day of the week.

int DAY_OF_WEEK_IN_MONTH

Field number for get and set indicating the ordinal number of the day of the week within the current month.

int DAY_OF_YEAR

Field number for get and set indicating the day number within the current year.

int DECEMBER

Value of the MONTH field indicating the twelfth month of the year.

int DOW_LOCAL

[icu] Field number for get() and set() indicating the localized day of week.

int DST_OFFSET

Field number for get and set indicating the daylight savings offset in milliseconds.

int EPOCH_JULIAN_DAY

The Julian day of the epoch, that is, January 1, 1970 on the Gregorian calendar.

int ERA

Field number for get and set indicating the era, e.g., AD or BC in the Julian calendar.

int EXTENDED_YEAR

[icu] Field number for get() and set() indicating the extended year.

int FEBRUARY

Value of the MONTH field indicating the second month of the year.

int FRIDAY

Value of the DAY_OF_WEEK field indicating Friday.

int GREATEST_MINIMUM

Limit type for getLimit() and handleGetLimit() indicating the greatest minimum value that a field can take.

int HOUR

Field number for get and set indicating the hour of the morning or afternoon.

int HOUR_OF_DAY

Field number for get and set indicating the hour of the day.

int INTERNALLY_SET

Value of the time stamp stamp[] indicating that a field has been set via computations from the time or from other fields.

int IS_LEAP_MONTH

[icu] Field indicating whether or not the current month is a leap month.

int JANUARY

Value of the MONTH field indicating the first month of the year.

int JAN_1_1_JULIAN_DAY

The Julian day of the Gregorian epoch, that is, January 1, 1 on the Gregorian calendar.

int JULIAN_DAY

[icu] Field number for get() and set() indicating the modified Julian day number.

int JULY

Value of the MONTH field indicating the seventh month of the year.

int JUNE

Value of the MONTH field indicating the sixth month of the year.

int LEAST_MAXIMUM

Limit type for getLimit() and handleGetLimit() indicating the least maximum value that a field can take.

int MARCH

Value of the MONTH field indicating the third month of the year.

int MAXIMUM

Limit type for getLimit() and handleGetLimit() indicating the maximum value that a field can take (greatest maximum).

int MAX_FIELD_COUNT

This constant was deprecated in API level 26. ICU 58 The numeric value may change over time, see ICU ticket #12420.

int MAX_JULIAN

The maximum supported Julian day.

long MAX_MILLIS

The maximum supported epoch milliseconds.

int MAY

Value of the MONTH field indicating the fifth month of the year.

int MILLISECOND

Field number for get and set indicating the millisecond within the second.

int MILLISECONDS_IN_DAY

[icu] Field number for get() and set() indicating the milliseconds in the day.

int MINIMUM

Limit type for getLimit() and handleGetLimit() indicating the minimum value that a field can take (least minimum).

int MINIMUM_USER_STAMP

If the time stamp stamp[] has a value greater than or equal to MINIMUM_USER_SET then it has been set by the user via a call to set().

int MINUTE

Field number for get and set indicating the minute within the hour.

int MIN_JULIAN

The minimum supported Julian day.

long MIN_MILLIS

The minimum supported epoch milliseconds.

int MONDAY

Value of the DAY_OF_WEEK field indicating Monday.

int MONTH

Field number for get and set indicating the month.

int NOVEMBER

Value of the MONTH field indicating the eleventh month of the year.

int OCTOBER

Value of the MONTH field indicating the tenth month of the year.

long ONE_DAY

The number of milliseconds in one day.

int ONE_HOUR

The number of milliseconds in one hour.

int ONE_MINUTE

The number of milliseconds in one minute.

int ONE_SECOND

The number of milliseconds in one second.

long ONE_WEEK

The number of milliseconds in one week.

int PM

Value of the AM_PM field indicating the period of the day from noon to just before midnight.

int RESOLVE_REMAP

Value to OR against resolve table field values for remapping.

int SATURDAY

Value of the DAY_OF_WEEK field indicating Saturday.

int SECOND

Field number for get and set indicating the second within the minute.

int SEPTEMBER

Value of the MONTH field indicating the ninth month of the year.

int SUNDAY

Value of the DAY_OF_WEEK field indicating Sunday.

int THURSDAY

Value of the DAY_OF_WEEK field indicating Thursday.

int TUESDAY

Value of the DAY_OF_WEEK field indicating Tuesday.

int UNDECIMBER

Value of the MONTH field indicating the thirteenth month of the year.

int UNSET

Value of the time stamp stamp[] indicating that a field has not been set since the last call to clear().

int WALLTIME_FIRST

[icu]Option used by setRepeatedWallTimeOption(int) and setSkippedWallTimeOption(int) specifying an ambiguous wall time to be interpreted as the earliest.

int WALLTIME_LAST

[icu]Option used by setRepeatedWallTimeOption(int) and setSkippedWallTimeOption(int) specifying an ambiguous wall time to be interpreted as the latest.

int WALLTIME_NEXT_VALID

[icu]Option used by setSkippedWallTimeOption(int) specifying an ambiguous wall time to be interpreted as the next valid wall time.

int WEDNESDAY

Value of the DAY_OF_WEEK field indicating Wednesday.

int WEEK_OF_MONTH

Field number for get and set indicating the week number within the current month.

int WEEK_OF_YEAR

Field number for get and set indicating the week number within the current year.

int YEAR

Field number for get and set indicating the year.

int YEAR_WOY

[icu] Field number for get() and set() indicating the extended year corresponding to the WEEK_OF_YEAR field.

int ZONE_OFFSET

Field number for get and set indicating the raw offset from GMT in milliseconds.

Fields

protected static final Date MAX_DATE

The maximum supported Date.

protected static final Date MIN_DATE

The minimum supported Date.

Protected constructors

Calendar()

Constructs a Calendar with the default time zone and the default FORMAT locale.

Calendar(TimeZone zone, Locale aLocale)

Constructs a calendar with the specified time zone and locale.

Calendar(TimeZone zone, ULocale locale)

Constructs a calendar with the specified time zone and locale.

Public methods

void add(int field, int amount)

Add a signed amount to a specified field, using this calendar's rules.

boolean after(Object when)

Compares the time field records.

boolean before(Object when)

Compares the time field records.

final void clear()

Clears the values of all the time fields.

final void clear(int field)

Clears the value in the given time field.

Object clone()

Overrides Cloneable

int compareTo(Calendar that)

Compares the times (in millis) represented by two Calendar objects.

boolean equals(Object obj)

Compares this calendar to the specified object.

int fieldDifference(Date when, int field)

[icu] Returns the difference between the given time and the time this calendar object is set to.

final int get(int field)

Returns the value for a given time field.

int getActualMaximum(int field)

Returns the maximum value that this field could have, given the current date.

int getActualMinimum(int field)

Returns the minimum value that this field could have, given the current date.

static Locale[] getAvailableLocales()

Returns the list of locales for which Calendars are installed.

DateFormat getDateTimeFormat(int dateStyle, int timeStyle, ULocale loc)

[icu] Returns a DateFormat appropriate to this calendar.

DateFormat getDateTimeFormat(int dateStyle, int timeStyle, Locale loc)

[icu] Returns a DateFormat appropriate to this calendar.

String getDisplayName(ULocale loc)

Returns the name of this calendar in the language of the given locale.

String getDisplayName(Locale loc)

Returns the name of this calendar in the language of the given locale.

final int getFieldCount()

[icu] Returns the number of fields defined by this calendar.

int getFirstDayOfWeek()

Returns what the first day of the week is, where 1 = SUNDAY and 7 = SATURDAY.

final int getGreatestMinimum(int field)

Returns the highest minimum value for the given field if varies.

static Calendar getInstance()

Returns a calendar using the default time zone and locale.

static Calendar getInstance(Locale aLocale)

Returns a calendar using the default time zone and specified locale.

static Calendar getInstance(TimeZone zone, Locale aLocale)

Returns a calendar with the specified time zone and locale.

static Calendar getInstance(TimeZone zone, ULocale locale)

Returns a calendar with the specified time zone and locale.

static Calendar getInstance(TimeZone zone)

Returns a calendar using the specified time zone and default locale.

static Calendar getInstance(ULocale locale)

Returns a calendar using the default time zone and specified locale.

static final String[] getKeywordValuesForLocale(String key, ULocale locale, boolean commonlyUsed)

[icu] Given a key and a locale, returns an array of string values in a preferred order that would make a difference.

final int getLeastMaximum(int field)

Returns the lowest maximum value for the given field if varies.

final int getMaximum(int field)

Returns the maximum value for the given time field.

int getMinimalDaysInFirstWeek()

Returns what the minimal days required in the first week of the year are.

final int getMinimum(int field)

Returns the minimum value for the given time field.

int getRepeatedWallTimeOption()

[icu]Gets the behavior for handling wall time repeating multiple times at negative time zone offset transitions.

int getSkippedWallTimeOption()

[icu]Gets the behavior for handling skipped wall time at positive time zone offset transitions.

final Date getTime()

Returns this Calendar's current time.

long getTimeInMillis()

Returns this Calendar's current time as a long.

TimeZone getTimeZone()

Returns the time zone.

String getType()

[icu] Returns the calendar type name string for this Calendar object.

Calendar.WeekData getWeekData()

[icu] Return simple, immutable struct-like class for access to the week data in this calendar.

static Calendar.WeekData getWeekDataForRegion(String region)

[icu] Return simple, immutable struct-like class for access to the CLDR week data.

int hashCode()

Returns a hash code for this calendar.

boolean isEquivalentTo(Calendar other)

[icu] Returns true if the given Calendar object is equivalent to this one.

boolean isLenient()

Tell whether date/time interpretation is to be lenient.

final boolean isSet(int field)

Determines if the given time field has a value set.

boolean isWeekend(Date date)

[icu] Returns true if the given date and time is in the weekend in this calendar system.

boolean isWeekend()

[icu] Returns true if this Calendar's current date and time is in the weekend in this calendar system.

final void roll(int field, boolean up)

Rolls (up/down) a single unit of time on the given field.

void roll(int field, int amount)

Rolls (up/down) a specified amount time on the given field.

final void set(int year, int month, int date, int hour, int minute, int second)

Sets the values for the fields year, month, date, hour, minute, and second.

final void set(int year, int month, int date, int hour, int minute)

Sets the values for the fields year, month, date, hour, and minute.

final void set(int field, int value)

Sets the time field with the given value.

final void set(int year, int month, int date)

Sets the values for the fields year, month, and date.

void setFirstDayOfWeek(int value)

Sets what the first day of the week is, where 1 = SUNDAY and 7 = SATURDAY.

void setLenient(boolean lenient)

Specify whether or not date/time interpretation is to be lenient.

void setMinimalDaysInFirstWeek(int value)

Sets what the minimal days required in the first week of the year are.

void setRepeatedWallTimeOption(int option)

[icu]Sets the behavior for handling wall time repeating multiple times at negative time zone offset transitions.

void setSkippedWallTimeOption(int option)

[icu]Sets the behavior for handling skipped wall time at positive time zone offset transitions.

final void setTime(Date date)

Sets this Calendar's current time with the given Date.

void setTimeInMillis(long millis)

Sets this Calendar's current time from the given long value.

void setTimeZone(TimeZone value)

Sets the time zone with the given time zone value.

Calendar setWeekData(Calendar.WeekData wdata)

[icu] Set data in this calendar based on the WeekData input.

String toString()

Returns a string representation of this calendar.

Protected methods

void complete()

Fills in any unset fields in the time field list.

void computeFields()

Converts the current millisecond time value time to field values in fields[].

final void computeGregorianFields(int julianDay)

Compute the Gregorian calendar year, month, and day of month from the Julian day.

int computeGregorianMonthStart(int year, int month)

Compute the Julian day of a month of the Gregorian calendar.

int computeJulianDay()

Compute the Julian day number as specified by this calendar's fields.

int computeMillisInDay()

This method was deprecated in API level 26. ICU 60

void computeTime()

Converts the current field values in fields[] to the millisecond time value time.

int computeZoneOffset(long millis, int millisInDay)

This method was deprecated in API level 26. ICU 60

String fieldName(int field)

Returns a string name for a field, for debugging and exceptions.

static final int floorDivide(int numerator, int denominator, int[] remainder)

Divide two integers, returning the floor of the quotient, and the modulus remainder.

static final int floorDivide(int numerator, int denominator)

Divide two integers, returning the floor of the quotient.

static final long floorDivide(long numerator, long denominator)

Divide two long integers, returning the floor of the quotient.

static final int floorDivide(long numerator, int denominator, int[] remainder)

Divide two integers, returning the floor of the quotient, and the modulus remainder.

int[][][] getFieldResolutionTable()

Returns the field resolution array for this calendar.

final int getGregorianDayOfMonth()

Returns the day of month (1-based) on the Gregorian calendar as computed by computeGregorianFields().

final int getGregorianDayOfYear()

Returns the day of year (1-based) on the Gregorian calendar as computed by computeGregorianFields().

final int getGregorianMonth()

Returns the month (0-based) on the Gregorian calendar as computed by computeGregorianFields().

final int getGregorianYear()

Returns the extended year on the Gregorian calendar as computed by computeGregorianFields().

int getLimit(int field, int limitType)

Returns a limit for a field.

final int getStamp(int field)

Returns the timestamp of a field.

static final int gregorianMonthLength(int y, int m)

Returns the length of a month of the Gregorian calendar.

static final int gregorianPreviousMonthLength(int y, int m)

Returns the length of a previous month of the Gregorian calendar.

void handleComputeFields(int julianDay)

Subclasses may override this method to compute several fields specific to each calendar system.

int handleComputeJulianDay(int bestField)

Subclasses may override this.

abstract int handleComputeMonthStart(int eyear, int month, boolean useMonth)

Returns the Julian day number of day before the first day of the given month in the given extended year.

int[] handleCreateFields()

Subclasses that use additional fields beyond those defined in Calendar should override this method to return an int[] array of the appropriate length.

DateFormat handleGetDateFormat(String pattern, String override, Locale locale)

Creates a DateFormat appropriate to this calendar.

DateFormat handleGetDateFormat(String pattern, ULocale locale)

Creates a DateFormat appropriate to this calendar.

DateFormat handleGetDateFormat(String pattern, Locale locale)

Creates a DateFormat appropriate to this calendar.

abstract int handleGetExtendedYear()

Returns the extended year defined by the current fields.

abstract int handleGetLimit(int field, int limitType)

Subclass API for defining limits of different types.

int handleGetMonthLength(int extendedYear, int month)

Returns the number of days in the given month of the given extended year of this calendar system.

int handleGetYearLength(int eyear)

Returns the number of days in the given extended year of this calendar system.

final int internalGet(int field)

Returns the value for a given time field.

final int internalGet(int field, int defaultValue)

Returns the value for a given time field, or return the given default value if the field is not set.

final long internalGetTimeInMillis()

Returns the current milliseconds without recomputing.

final void internalSet(int field, int value)

Set a field to a value.

static final boolean isGregorianLeapYear(int year)

Determines if the given year is a leap year.

static final int julianDayToDayOfWeek(int julian)

Returns the day of week, from SUNDAY to SATURDAY, given a Julian day.

static final long julianDayToMillis(int julian)

Converts Julian day to time as milliseconds.

static final int millisToJulianDay(long millis)

Converts time as milliseconds to Julian day.

int newerField(int defaultField, int alternateField)

Returns the field that is newer, either defaultField, or alternateField.

int newestStamp(int first, int last, int bestStampSoFar)

Returns the newest stamp of a given range of fields.

void pinField(int field)

Adjust the specified field so that it is within the allowable range for the date to which this calendar is set.

void prepareGetActual(int field, boolean isMinimum)

Prepare this calendar for computing the actual minimum or maximum.

int resolveFields(int[][][] precedenceTable)

Given a precedence table, return the newest field combination in the table, or -1 if none is found.

void validateField(int field)

Validate a single field of this calendar.

final void validateField(int field, int min, int max)

Validate a single field of this calendar given its minimum and maximum allowed value.

void validateFields()

Ensure that each field is within its valid range by calling validateField(int) on each field that has been set.

int weekNumber(int desiredDay, int dayOfPeriod, int dayOfWeek)

Returns the week number of a day, within a period.

final int weekNumber(int dayOfPeriod, int dayOfWeek)

Returns the week number of a day, within a period.

Inherited methods

Constants

AM

Added in API level 24 
public static final int AM

Value of the AM_PM field indicating the period of the day from midnight to just before noon.

Constant Value: 0 (0x00000000)

AM_PM

Added in API level 24 
public static final int AM_PM

Field number for get and set indicating whether the HOUR is before or after noon. E.g., at 10:04:15.250 PM the AM_PM is PM.

See also:

Constant Value: 9 (0x00000009)

APRIL

Added in API level 24 
public static final int APRIL

Value of the MONTH field indicating the fourth month of the year.

Constant Value: 3 (0x00000003)

AUGUST

Added in API level 24 
public static final int AUGUST

Value of the MONTH field indicating the eighth month of the year.

Constant Value: 7 (0x00000007)

DATE

Added in API level 24 
public static final int DATE

Field number for get and set indicating the day of the month. This is a synonym for DAY_OF_MONTH. The first day of the month has value 1.

See also:

Constant Value: 5 (0x00000005)

DAY_OF_MONTH

Added in API level 24 
public static final int DAY_OF_MONTH

Field number for get and set indicating the day of the month. This is a synonym for DATE. The first day of the month has value 1.

See also:

Constant Value: 5 (0x00000005)

DAY_OF_WEEK

Added in API level 24 
public static final int DAY_OF_WEEK

Field number for get and set indicating the day of the week. This field takes values SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.

Constant Value: 7 (0x00000007)

DAY_OF_WEEK_IN_MONTH

Added in API level 24 
public static final int DAY_OF_WEEK_IN_MONTH

Field number for get and set indicating the ordinal number of the day of the week within the current month. Together with the DAY_OF_WEEK field, this uniquely specifies a day within a month. Unlike WEEK_OF_MONTH and WEEK_OF_YEAR, this field's value does not depend on getFirstDayOfWeek() or getMinimalDaysInFirstWeek(). DAY_OF_MONTH 1 through 7 always correspond to DAY_OF_WEEK_IN_MONTH 1; 8 through 15 correspond to DAY_OF_WEEK_IN_MONTH 2, and so on. DAY_OF_WEEK_IN_MONTH 0 indicates the week before DAY_OF_WEEK_IN_MONTH 1. Negative values count back from the end of the month, so the last Sunday of a month is specified as DAY_OF_WEEK = SUNDAY, DAY_OF_WEEK_IN_MONTH = -1. Because negative values count backward they will usually be aligned differently within the month than positive values. For example, if a month has 31 days, DAY_OF_WEEK_IN_MONTH -1 will overlap DAY_OF_WEEK_IN_MONTH 5 and the end of 4.

Constant Value: 8 (0x00000008)

DAY_OF_YEAR

Added in API level 24 
public static final int DAY_OF_YEAR

Field number for get and set indicating the day number within the current year. The first day of the year has value 1.

Constant Value: 6 (0x00000006)

DECEMBER

Added in API level 24 
public static final int DECEMBER

Value of the MONTH field indicating the twelfth month of the year.

Constant Value: 11 (0x0000000b)

DOW_LOCAL

Added in API level 24 
public static final int DOW_LOCAL

[icu] Field number for get() and set() indicating the localized day of week. This will be a value from 1 to 7 inclusive, with 1 being the localized first day of the week.

Constant Value: 18 (0x00000012)

DST_OFFSET

Added in API level 24 
public static final int DST_OFFSET

Field number for get and set indicating the daylight savings offset in milliseconds.

Constant Value: 16 (0x00000010)

EPOCH_JULIAN_DAY

Added in API level 24 
protected static final int EPOCH_JULIAN_DAY

The Julian day of the epoch, that is, January 1, 1970 on the Gregorian calendar.

Constant Value: 2440588 (0x00253d8c)

ERA

Added in API level 24 
public static final int ERA

Field number for get and set indicating the era, e.g., AD or BC in the Julian calendar. This is a calendar-specific value; see subclass documentation.

Constant Value: 0 (0x00000000)

EXTENDED_YEAR

Added in API level 24 
public static final int EXTENDED_YEAR

[icu] Field number for get() and set() indicating the extended year. This is a single number designating the year of this calendar system, encompassing all supra-year fields. For example, for the Julian calendar system, year numbers are positive, with an era of BCE or CE. An extended year value for the Julian calendar system assigns positive values to CE years and negative values to BCE years, with 1 BCE being year 0.

Constant Value: 19 (0x00000013)

FEBRUARY

Added in API level 24 
public static final int FEBRUARY

Value of the MONTH field indicating the second month of the year.

Constant Value: 1 (0x00000001)

FRIDAY

Added in API level 24 
public static final int FRIDAY

Value of the DAY_OF_WEEK field indicating Friday.

Constant Value: 6 (0x00000006)

GREATEST_MINIMUM

Added in API level 24 
protected static final int GREATEST_MINIMUM

Limit type for getLimit() and handleGetLimit() indicating the greatest minimum value that a field can take.

Constant Value: 1 (0x00000001)

HOUR

Added in API level 24 
public static final int HOUR

Field number for get and set indicating the hour of the morning or afternoon. HOUR is used for the 12-hour clock. E.g., at 10:04:15.250 PM the HOUR is 10.

See also:

Constant Value: 10 (0x0000000a)

HOUR_OF_DAY

Added in API level 24 
public static final int HOUR_OF_DAY

Field number for get and set indicating the hour of the day. HOUR_OF_DAY is used for the 24-hour clock. E.g., at 10:04:15.250 PM the HOUR_OF_DAY is 22.

See also:

Constant Value: 11 (0x0000000b)

INTERNALLY_SET

Added in API level 24 
protected static final int INTERNALLY_SET

Value of the time stamp stamp[] indicating that a field has been set via computations from the time or from other fields.

Constant Value: 1 (0x00000001)

IS_LEAP_MONTH

Added in API level 24 
public static final int IS_LEAP_MONTH

[icu] Field indicating whether or not the current month is a leap month. Should have a value of 0 for non-leap months, and 1 for leap months.

Constant Value: 22 (0x00000016)

JANUARY

Added in API level 24 
public static final int JANUARY

Value of the MONTH field indicating the first month of the year.

Constant Value: 0 (0x00000000)

JAN_1_1_JULIAN_DAY

Added in API level 24 
protected static final int JAN_1_1_JULIAN_DAY

The Julian day of the Gregorian epoch, that is, January 1, 1 on the Gregorian calendar.

Constant Value: 1721426 (0x001a4452)

JULIAN_DAY

Added in API level 24 
public static final int JULIAN_DAY

[icu] Field number for get() and set() indicating the modified Julian day number. This is different from the conventional Julian day number in two regards. First, it demarcates days at local zone midnight, rather than noon GMT. Second, it is a local number; that is, it depends on the local time zone. It can be thought of as a single number that encompasses all the date-related fields.

Constant Value: 20 (0x00000014)

JULY

Added in API level 24 
public static final int JULY

Value of the MONTH field indicating the seventh month of the year.

Constant Value: 6 (0x00000006)

JUNE

Added in API level 24 
public static final int JUNE

Value of the MONTH field indicating the sixth month of the year.

Constant Value: 5 (0x00000005)

LEAST_MAXIMUM

Added in API level 24 
protected static final int LEAST_MAXIMUM

Limit type for getLimit() and handleGetLimit() indicating the least maximum value that a field can take.

Constant Value: 2 (0x00000002)

MARCH

Added in API level 24 
public static final int MARCH

Value of the MONTH field indicating the third month of the year.

Constant Value: 2 (0x00000002)

MAXIMUM

Added in API level 24 
protected static final int MAXIMUM

Limit type for getLimit() and handleGetLimit() indicating the maximum value that a field can take (greatest maximum).

Constant Value: 3 (0x00000003)

MAX_FIELD_COUNT

Added in API level 24
Deprecated in API level 26 
protected static final int MAX_FIELD_COUNT

This constant was deprecated in API level 26.
ICU 58 The numeric value may change over time, see ICU ticket #12420.

The maximum number of fields possible. Subclasses must not define more total fields than this number.

Constant Value: 32 (0x00000020)

MAX_JULIAN

Added in API level 24 
protected static final int MAX_JULIAN

The maximum supported Julian day. This value is equivalent to MAX_MILLIS and MAX_DATE.

See also:

Constant Value: 2130706432 (0x7f000000)

MAX_MILLIS

Added in API level 24 
protected static final long MAX_MILLIS

The maximum supported epoch milliseconds. This value is equivalent to MAX_JULIAN and MAX_DATE.

Constant Value: 183882168921600000 (0x028d47dbbf19b000)

MAY

Added in API level 24 
public static final int MAY

Value of the MONTH field indicating the fifth month of the year.

Constant Value: 4 (0x00000004)

MILLISECOND

Added in API level 24 
public static final int MILLISECOND

Field number for get and set indicating the millisecond within the second. E.g., at 10:04:15.250 PM the MILLISECOND is 250.

Constant Value: 14 (0x0000000e)

MILLISECONDS_IN_DAY

Added in API level 24 
public static final int MILLISECONDS_IN_DAY

[icu] Field number for get() and set() indicating the milliseconds in the day. This ranges from 0 to 23:59:59.999 (regardless of DST). This field behaves exactly like a composite of all time-related fields, not including the zone fields. As such, it also reflects discontinuities of those fields on DST transition days. On a day of DST onset, it will jump forward. On a day of DST cessation, it will jump backward. This reflects the fact that is must be combined with the DST_OFFSET field to obtain a unique local time value.

Constant Value: 21 (0x00000015)

MINIMUM

Added in API level 24 
protected static final int MINIMUM

Limit type for getLimit() and handleGetLimit() indicating the minimum value that a field can take (least minimum).

Constant Value: 0 (0x00000000)

MINIMUM_USER_STAMP

Added in API level 24 
protected static final int MINIMUM_USER_STAMP

If the time stamp stamp[] has a value greater than or equal to MINIMUM_USER_SET then it has been set by the user via a call to set().

Constant Value: 2 (0x00000002)

MINUTE

Added in API level 24 
public static final int MINUTE

Field number for get and set indicating the minute within the hour. E.g., at 10:04:15.250 PM the MINUTE is 4.

Constant Value: 12 (0x0000000c)

MIN_JULIAN

Added in API level 24 
protected static final int MIN_JULIAN

The minimum supported Julian day. This value is equivalent to MIN_MILLIS and MIN_DATE.

See also:

Constant Value: -2130706432 (0x81000000)

MIN_MILLIS

Added in API level 24 
protected static final long MIN_MILLIS

The minimum supported epoch milliseconds. This value is equivalent to MIN_JULIAN and MIN_DATE.

Constant Value: -184303902528000000 (0xfd713893bf19b000)

MONDAY

Added in API level 24 
public static final int MONDAY

Value of the DAY_OF_WEEK field indicating Monday.

Constant Value: 2 (0x00000002)

MONTH

Added in API level 24 
public static final int MONTH

Field number for get and set indicating the month. This is a calendar-specific value. The first month of the year is JANUARY; the last depends on the number of months in a year.

Constant Value: 2 (0x00000002)

NOVEMBER

Added in API level 24 
public static final int NOVEMBER

Value of the MONTH field indicating the eleventh month of the year.

Constant Value: 10 (0x0000000a)

OCTOBER

Added in API level 24 
public static final int OCTOBER

Value of the MONTH field indicating the tenth month of the year.

Constant Value: 9 (0x00000009)

ONE_DAY

Added in API level 24 
protected static final long ONE_DAY

The number of milliseconds in one day. Although ONE_DAY and ONE_WEEK can fit into ints, they must be longs in order to prevent arithmetic overflow when performing (bug 4173516).

Constant Value: 86400000 (0x0000000005265c00)

ONE_HOUR

Added in API level 24 
protected static final int ONE_HOUR

The number of milliseconds in one hour.

Constant Value: 3600000 (0x0036ee80)

ONE_MINUTE

Added in API level 24 
protected static final int ONE_MINUTE

The number of milliseconds in one minute.

Constant Value: 60000 (0x0000ea60)

ONE_SECOND

Added in API level 24 
protected static final int ONE_SECOND

The number of milliseconds in one second.

Constant Value: 1000 (0x000003e8)

ONE_WEEK

Added in API level 24 
protected static final long ONE_WEEK

The number of milliseconds in one week. Although ONE_DAY and ONE_WEEK can fit into ints, they must be longs in order to prevent arithmetic overflow when performing (bug 4173516).

Constant Value: 604800000 (0x00000000240c8400)

PM

Added in API level 24 
public static final int PM

Value of the AM_PM field indicating the period of the day from noon to just before midnight.

Constant Value: 1 (0x00000001)

RESOLVE_REMAP

Added in API level 24 
protected static final int RESOLVE_REMAP

Value to OR against resolve table field values for remapping.

See also:

Constant Value: 32 (0x00000020)

SATURDAY

Added in API level 24 
public static final int SATURDAY

Value of the DAY_OF_WEEK field indicating Saturday.

Constant Value: 7 (0x00000007)

SECOND

Added in API level 24 
public static final int SECOND

Field number for get and set indicating the second within the minute. E.g., at 10:04:15.250 PM the SECOND is 15.

Constant Value: 13 (0x0000000d)

SEPTEMBER

Added in API level 24 
public static final int SEPTEMBER

Value of the MONTH field indicating the ninth month of the year.

Constant Value: 8 (0x00000008)

SUNDAY

Added in API level 24 
public static final int SUNDAY

Value of the DAY_OF_WEEK field indicating Sunday.

Constant Value: 1 (0x00000001)

THURSDAY

Added in API level 24 
public static final int THURSDAY

Value of the DAY_OF_WEEK field indicating Thursday.

Constant Value: 5 (0x00000005)

TUESDAY

Added in API level 24 
public static final int TUESDAY

Value of the DAY_OF_WEEK field indicating Tuesday.

Constant Value: 3 (0x00000003)

UNDECIMBER

Added in API level 24 
public static final int UNDECIMBER

Value of the MONTH field indicating the thirteenth month of the year. Although GregorianCalendar does not use this value, lunar calendars do.

Constant Value: 12 (0x0000000c)

UNSET

Added in API level 24 
protected static final int UNSET

Value of the time stamp stamp[] indicating that a field has not been set since the last call to clear().

Constant Value: 0 (0x00000000)

WALLTIME_FIRST

Added in API level 24 
public static final int WALLTIME_FIRST

[icu]Option used by setRepeatedWallTimeOption(int) and setSkippedWallTimeOption(int) specifying an ambiguous wall time to be interpreted as the earliest.

Constant Value: 1 (0x00000001)

WALLTIME_LAST

Added in API level 24 
public static final int WALLTIME_LAST

[icu]Option used by setRepeatedWallTimeOption(int) and setSkippedWallTimeOption(int) specifying an ambiguous wall time to be interpreted as the latest.

Constant Value: 0 (0x00000000)

WALLTIME_NEXT_VALID

Added in API level 24 
public static final int WALLTIME_NEXT_VALID

[icu]Option used by setSkippedWallTimeOption(int) specifying an ambiguous wall time to be interpreted as the next valid wall time.

Constant Value: 2 (0x00000002)

WEDNESDAY

Added in API level 24 
public static final int WEDNESDAY

Value of the DAY_OF_WEEK field indicating Wednesday.

Constant Value: 4 (0x00000004)

WEEK_OF_MONTH

Added in API level 24 
public static final int WEEK_OF_MONTH

Field number for get and set indicating the week number within the current month. The first week of the month, as defined by getFirstDayOfWeek() and getMinimalDaysInFirstWeek(), has value 1. Subclasses define the value of WEEK_OF_MONTH for days before the first week of the month.

Constant Value: 4 (0x00000004)

WEEK_OF_YEAR

Added in API level 24 
public static final int WEEK_OF_YEAR

Field number for get and set indicating the week number within the current year. The first week of the year, as defined by getFirstDayOfWeek() and getMinimalDaysInFirstWeek(), has value 1. Subclasses define the value of WEEK_OF_YEAR for days before the first week of the year.

Constant Value: 3 (0x00000003)

YEAR

Added in API level 24 
public static final int YEAR

Field number for get and set indicating the year. This is a calendar-specific value; see subclass documentation.

Constant Value: 1 (0x00000001)

YEAR_WOY

Added in API level 24 
public static final int YEAR_WOY

[icu] Field number for get() and set() indicating the extended year corresponding to the WEEK_OF_YEAR field. This may be one greater or less than the value of EXTENDED_YEAR.

Constant Value: 17 (0x00000011)

ZONE_OFFSET

Added in API level 24 
public static final int ZONE_OFFSET

Field number for get and set indicating the raw offset from GMT in milliseconds.

Constant Value: 15 (0x0000000f)

Fields

MAX_DATE

Added in API level 24 
protected static final Date MAX_DATE

The maximum supported Date. This value is equivalent to MAX_JULIAN and MAX_MILLIS.

MIN_DATE

Added in API level 24 
protected static final Date MIN_DATE

The minimum supported Date. This value is equivalent to MIN_JULIAN and MIN_MILLIS.

Protected constructors

Calendar

Added in API level 24 
protected Calendar ()

Constructs a Calendar with the default time zone and the default FORMAT locale.

Calendar

Added in API level 24 
protected Calendar (TimeZone zone, 
                Locale aLocale)

Constructs a calendar with the specified time zone and locale.

Parameters
zone TimeZone: the time zone to use
aLocale Locale: the locale for the week data

Calendar

Added in API level 24 
protected Calendar (TimeZone zone, 
                ULocale locale)

Constructs a calendar with the specified time zone and locale.

Parameters
zone TimeZone: the time zone to use
locale ULocale: the ulocale for the week data

Public methods

add

Added in API level 24 
public void add (int field, 
                int amount)

Add a signed amount to a specified field, using this calendar's rules. For example, to add three days to the current date, you can call add(Calendar.DATE, 3).

When adding to certain fields, the values of other fields may conflict and need to be changed. For example, when adding one to the MONTH field for the Gregorian date 1/31/96, the DAY_OF_MONTH field must be adjusted so that the result is 2/29/96 rather than the invalid 2/31/96.

Adding a positive value always means moving forward in time, so for the Gregorian calendar, starting with 100 BC and adding +1 to year results in 99 BC (even though this actually reduces the numeric value of the field itself).

[icu] Note: The ICU implementation of this method is able to add to all fields except for ERA, DST_OFFSET, and ZONE_OFFSET. Subclasses may, of course, add support for additional fields in their overrides of add.

Note: You should always use roll and add rather than attempting to perform arithmetic operations directly on the fields of a Calendar. It is quite possible for Calendar subclasses to have fields with non-linear behavior, for example missing months or days during non-leap years. The subclasses' add and roll methods will take this into account, while simple arithmetic manipulations may give invalid results.

Subclassing:
This implementation of add assumes that the behavior of the field is continuous between its minimum and maximum, which are found by calling getActualMinimum and getActualMaximum. For such fields, simple arithmetic operations are sufficient to perform the add.

Subclasses that have fields for which this assumption of continuity breaks down must override add to handle those fields specially. For example, in the Hebrew calendar the month "Adar I" only occurs in leap years; in other years the calendar jumps from Shevat (month #4) to Adar (month #6). The HebrewCalendar.add method takes this into account, so that adding one month to a date in Shevat gives the proper result (Adar) in a non-leap year.

Parameters
field int: the time field.
amount int: the amount to add to the field.
Throws
IllegalArgumentException if the field is invalid or refers to a field that cannot be handled by this method.

See also:

after

Added in API level 24 
public boolean after (Object when)

Compares the time field records. Equivalent to comparing result of conversion to UTC.

Parameters
when Object: the Calendar to be compared with this Calendar.
Returns
boolean true if the current time of this Calendar is after the time of Calendar when; false otherwise.

before

Added in API level 24 
public boolean before (Object when)

Compares the time field records. Equivalent to comparing result of conversion to UTC.

Parameters
when Object: the Calendar to be compared with this Calendar.
Returns
boolean true if the current time of this Calendar is before the time of Calendar when; false otherwise.

clear

Added in API level 24 
public final void clear ()

Clears the values of all the time fields.

clear

Added in API level 24 
public final void clear (int field)

Clears the value in the given time field.

Parameters
field int: the time field to be cleared.

clone

Added in API level 24 
public Object clone ()

Overrides Cloneable

Returns
Object a clone of this instance.

compareTo

Added in API level 24 
public int compareTo (Calendar that)

Compares the times (in millis) represented by two Calendar objects.

Parameters
that Calendar: the Calendar to compare to this.
Returns
int 0 if the time represented by this Calendar is equal to the time represented by that Calendar, a value less than 0 if the time represented by this is before the time represented by that, and a value greater than 0 if the time represented by this is after the time represented by that.
Throws
NullPointerException if that Calendar is null.
IllegalArgumentException if the time of that Calendar can't be obtained because of invalid calendar values.

equals

Added in API level 24 
public boolean equals (Object obj)

Compares this calendar to the specified object. The result is true if and only if the argument is not null and is a Calendar object that represents the same calendar as this object.

Parameters
obj Object: the object to compare with.
Returns
boolean true if the objects are the same; false otherwise.

fieldDifference

Added in API level 24 
public int fieldDifference (Date when, 
                int field)

[icu] Returns the difference between the given time and the time this calendar object is set to. If this calendar is set before the given time, the returned value will be positive. If this calendar is set after the given time, the returned value will be negative. The field parameter specifies the units of the return value. For example, if fieldDifference(when, Calendar.MONTH) returns 3, then this calendar is set to 3 months before when, and possibly some additional time less than one month.

As a side effect of this call, this calendar is advanced toward when by the given amount. That is, calling this method has the side effect of calling add(field, n), where n is the return value.

Usage: To use this method, call it first with the largest field of interest, then with progressively smaller fields. For example: 

 int y = cal.fieldDifference(when, Calendar.YEAR);
 int m = cal.fieldDifference(when, Calendar.MONTH);
 int d = cal.fieldDifference(when, Calendar.DATE);
 computes the difference between cal and when in years, months, and days.

Note: fieldDifference() is asymmetrical. That is, in the following code: 

 cal.setTime(date1);
 int m1 = cal.fieldDifference(date2, Calendar.MONTH);
 int d1 = cal.fieldDifference(date2, Calendar.DATE);
 cal.setTime(date2);
 int m2 = cal.fieldDifference(date1, Calendar.MONTH);
 int d2 = cal.fieldDifference(date1, Calendar.DATE);
 one might expect that m1 == -m2 && d1 == -d2. However, this is not generally the case, because of irregularities in the underlying calendar system (e.g., the Gregorian calendar has a varying number of days per month).

Parameters
when Date: the date to compare this calendar's time to
field int: the field in which to compute the result
Returns
int the difference, either positive or negative, between this calendar's time and when, in terms of field.

get

Added in API level 24 
public final int get (int field)

Returns the value for a given time field.

Parameters
field int: the given time field.
Returns
int the value for the given time field.

getActualMaximum

Added in API level 24 
public int getActualMaximum (int field)

Returns the maximum value that this field could have, given the current date. For example, with the Gregorian date February 3, 1997 and the DAY_OF_MONTH field, the actual maximum is 28; for February 3, 1996 it is 29.

The actual maximum computation ignores smaller fields and the current value of like-sized fields. For example, the actual maximum of the DAY_OF_YEAR or MONTH depends only on the year and supra-year fields. The actual maximum of the DAY_OF_MONTH depends, in addition, on the MONTH field and any other fields at that granularity (such as IS_LEAP_MONTH). The DAY_OF_WEEK_IN_MONTH field does not depend on the current DAY_OF_WEEK; it returns the maximum for any day of week in the current month. Likewise for the WEEK_OF_MONTH and WEEK_OF_YEAR fields.

Parameters
field int: the field whose maximum is desired
Returns
int the maximum of the given field for the current date of this calendar

getActualMinimum

Added in API level 24 
public int getActualMinimum (int field)

Returns the minimum value that this field could have, given the current date. For most fields, this is the same as getMinimum and getGreatestMinimum. However, some fields, especially those related to week number, are more complicated.

For example, assume getMinimalDaysInFirstWeek returns 4 and getFirstDayOfWeek returns SUNDAY. If the first day of the month is Sunday, Monday, Tuesday, or Wednesday there will be four or more days in the first week, so it will be week number 1, and getActualMinimum(WEEK_OF_MONTH) will return 1. However, if the first of the month is a Thursday, Friday, or Saturday, there are not four days in that week, so it is week number 0, and getActualMinimum(WEEK_OF_MONTH) will return 0.

Parameters
field int: the field whose actual minimum value is desired.
Returns
int the minimum of the given field for the current date of this calendar

getAvailableLocales

Added in API level 24 
public static Locale[] getAvailableLocales ()

Returns the list of locales for which Calendars are installed.

Returns
Locale[] the list of locales for which Calendars are installed.

getDateTimeFormat

Added in API level 24 
public DateFormat getDateTimeFormat (int dateStyle, 
                int timeStyle, 
                ULocale loc)

[icu] Returns a DateFormat appropriate to this calendar. Subclasses wishing to specialize this behavior should override handleGetDateFormat(String, ULocale).

Parameters
dateStyle int

timeStyle int

loc ULocale

Returns
DateFormat

getDateTimeFormat

Added in API level 24 
public DateFormat getDateTimeFormat (int dateStyle, 
                int timeStyle, 
                Locale loc)

[icu] Returns a DateFormat appropriate to this calendar. Subclasses wishing to specialize this behavior should override handleGetDateFormat(String, ULocale).

Parameters
dateStyle int

timeStyle int

loc Locale

Returns
DateFormat

getDisplayName

Added in API level 24 
public String getDisplayName (ULocale loc)

Returns the name of this calendar in the language of the given locale.

Parameters
loc ULocale

Returns
String

getDisplayName

Added in API level 24 
public String getDisplayName (Locale loc)

Returns the name of this calendar in the language of the given locale.

Parameters
loc Locale

Returns
String

getFieldCount

Added in API level 24 
public final int getFieldCount ()

[icu] Returns the number of fields defined by this calendar. Valid field arguments to set() and get() are 0..getFieldCount()-1.

Returns
int

getFirstDayOfWeek

Added in API level 24 
public int getFirstDayOfWeek ()

Returns what the first day of the week is, where 1 = SUNDAY and 7 = SATURDAY. e.g., Sunday in US, Monday in France

Returns
int the first day of the week, where 1 = SUNDAY and 7 = SATURDAY.

getGreatestMinimum

Added in API level 24 
public final int getGreatestMinimum (int field)

Returns the highest minimum value for the given field if varies. Otherwise same as getMinimum(). For Gregorian, no difference.

Parameters
field int: the given time field.
Returns
int the highest minimum value for the given time field.

getInstance

Added in API level 24 
public static Calendar getInstance ()

Returns a calendar using the default time zone and locale.

Returns
Calendar a Calendar.

getInstance

Added in API level 24 
public static Calendar getInstance (Locale aLocale)

Returns a calendar using the default time zone and specified locale.

Parameters
aLocale Locale: the locale for the week data
Returns
Calendar a Calendar.

getInstance

Added in API level 24 
public static Calendar getInstance (TimeZone zone, 
                Locale aLocale)

Returns a calendar with the specified time zone and locale.

Parameters
zone TimeZone: the time zone to use
aLocale Locale: the locale for the week data
Returns
Calendar a Calendar.

getInstance

Added in API level 24 
public static Calendar getInstance (TimeZone zone, 
                ULocale locale)

Returns a calendar with the specified time zone and locale.

Parameters
zone TimeZone: the time zone to use
locale ULocale: the ulocale for the week data
Returns
Calendar a Calendar.

getInstance

Added in API level 24 
public static Calendar getInstance (TimeZone zone)

Returns a calendar using the specified time zone and default locale.

Parameters
zone TimeZone: the time zone to use
Returns
Calendar a Calendar.

getInstance

Added in API level 24 
public static Calendar getInstance (ULocale locale)

Returns a calendar using the default time zone and specified locale.

Parameters
locale ULocale: the ulocale for the week data
Returns
Calendar a Calendar.

getKeywordValuesForLocale

Added in API level 24 
public static final String[] getKeywordValuesForLocale (String key, 
                ULocale locale, 
                boolean commonlyUsed)

[icu] Given a key and a locale, returns an array of string values in a preferred order that would make a difference. These are all and only those values where the open (creation) of the service with the locale formed from the input locale plus input keyword and that value has different behavior than creation with the input locale alone.

Parameters
key String: one of the keys supported by this service. For now, only "calendar" is supported.
locale ULocale: the locale
commonlyUsed boolean: if set to true it will return only commonly used values with the given locale in preferred order. Otherwise, it will return all the available values for the locale.
Returns
String[] an array of string values for the given key and the locale.

getLeastMaximum

Added in API level 24 
public final int getLeastMaximum (int field)

Returns the lowest maximum value for the given field if varies. Otherwise same as getMaximum(). e.g., for Gregorian DAY_OF_MONTH, 28.

Parameters
field int: the given time field.
Returns
int the lowest maximum value for the given time field.

getMaximum

Added in API level 24 
public final int getMaximum (int field)

Returns the maximum value for the given time field. e.g. for Gregorian DAY_OF_MONTH, 31.

Parameters
field int: the given time field.
Returns
int the maximum value for the given time field.

getMinimalDaysInFirstWeek

Added in API level 24 
public int getMinimalDaysInFirstWeek ()

Returns what the minimal days required in the first week of the year are. That is, if the first week is defined as one that contains the first day of the first month of a year, getMinimalDaysInFirstWeek returns 1. If the minimal days required must be a full week, getMinimalDaysInFirstWeek returns 7.

Returns
int the minimal days required in the first week of the year.

getMinimum

Added in API level 24 
public final int getMinimum (int field)

Returns the minimum value for the given time field. e.g., for Gregorian DAY_OF_MONTH, 1.

Parameters
field int: the given time field.
Returns
int the minimum value for the given time field.

getRepeatedWallTimeOption

Added in API level 24 
public int getRepeatedWallTimeOption ()

[icu]Gets the behavior for handling wall time repeating multiple times at negative time zone offset transitions.

Returns
int the behavior for handling repeating wall time, either WALLTIME_FIRST or WALLTIME_LAST.

getSkippedWallTimeOption

Added in API level 24 
public int getSkippedWallTimeOption ()

[icu]Gets the behavior for handling skipped wall time at positive time zone offset transitions.

Returns
int the behavior for handling skipped wall time, one of WALLTIME_FIRST, WALLTIME_LAST and WALLTIME_NEXT_VALID.

getTime

Added in API level 24 
public final Date getTime ()

Returns this Calendar's current time.

Returns
Date the current time.

getTimeInMillis

Added in API level 24 
public long getTimeInMillis ()

Returns this Calendar's current time as a long.

Returns
long the current time as UTC milliseconds from the epoch.

getTimeZone

Added in API level 24 
public TimeZone getTimeZone ()

Returns the time zone.

Returns
TimeZone the time zone object associated with this calendar.

getType

Added in API level 24 
public String getType ()

[icu] Returns the calendar type name string for this Calendar object. The returned string is the legacy ICU calendar attribute value, for example, "gregorian" or "japanese".

See type="old type name" for the calendar attribute of locale IDs at http://www.unicode.org/reports/tr35/#Key_Type_Definitions

Returns
String legacy calendar type name string

getWeekData

Added in API level 24 
public Calendar.WeekData getWeekData ()

[icu] Return simple, immutable struct-like class for access to the week data in this calendar.

Returns
Calendar.WeekData the WeekData for this calendar.

getWeekDataForRegion

Added in API level 24 
public static Calendar.WeekData getWeekDataForRegion (String region)

[icu] Return simple, immutable struct-like class for access to the CLDR week data.

Parameters
region String: The input region. The results are undefined if the region code is not valid.
Returns
Calendar.WeekData the WeekData for the input region. It is never null.

hashCode

Added in API level 24 
public int hashCode ()

Returns a hash code for this calendar.

Returns
int a hash code value for this object.

isEquivalentTo

Added in API level 24 
public boolean isEquivalentTo (Calendar other)

[icu] Returns true if the given Calendar object is equivalent to this one. An equivalent Calendar will behave exactly as this one does, but it may be set to a different time. By contrast, for the equals() method to return true, the other Calendar must be set to the same time.

Parameters
other Calendar: the Calendar to be compared with this Calendar
Returns
boolean

isLenient

Added in API level 24 
public boolean isLenient ()

Tell whether date/time interpretation is to be lenient.

Returns
boolean

isSet

Added in API level 24 
public final boolean isSet (int field)

Determines if the given time field has a value set.

Parameters
field int

Returns
boolean true if the given time field has a value set; false otherwise.

isWeekend

Added in API level 24 
public boolean isWeekend (Date date)

[icu] Returns true if the given date and time is in the weekend in this calendar system. Equivalent to calling setTime() followed by isWeekend(). Note: This method changes the time this calendar is set to.

Parameters
date Date: the date and time
Returns
boolean true if the given date and time is part of the weekend

See also:

isWeekend

Added in API level 24 
public boolean isWeekend ()

[icu] Returns true if this Calendar's current date and time is in the weekend in this calendar system.

Returns
boolean true if the given date and time is part of the weekend

See also:

roll

Added in API level 24 
public final void roll (int field, 
                boolean up)

Rolls (up/down) a single unit of time on the given field. If the field is rolled past its maximum allowable value, it will "wrap" back to its minimum and continue rolling. For example, to roll the current date up by one day, you can call:

roll(DATE, true)

When rolling on the YEAR field, it will roll the year value in the range between 1 and the value returned by calling getMaximum(YEAR).

When rolling on certain fields, the values of other fields may conflict and need to be changed. For example, when rolling the MONTH field for the Gregorian date 1/31/96 upward, the DAY_OF_MONTH field must be adjusted so that the result is 2/29/96 rather than the invalid 2/31/96.

Rolling up always means rolling forward in time (unless the limit of the field is reached, in which case it may pin or wrap), so for the Gregorian calendar, starting with 100 BC and rolling the year up results in 99 BC. When eras have a definite beginning and end (as in the Chinese calendar, or as in most eras in the Japanese calendar) then rolling the year past either limit of the era will cause the year to wrap around. When eras only have a limit at one end, then attempting to roll the year past that limit will result in pinning the year at that limit. Note that for most calendars in which era 0 years move forward in time (such as Buddhist, Hebrew, or Islamic), it is possible for add or roll to result in negative years for era 0 (that is the only way to represent years before the calendar epoch in such calendars).

Note: Calling roll(field, true) N times is not necessarily equivalent to calling roll(field, N). For example, imagine that you start with the date Gregorian date January 31, 1995. If you call roll(Calendar.MONTH, 2), the result will be March 31, 1995. But if you call roll(Calendar.MONTH, true), the result will be February 28, 1995. Calling it one more time will give March 28, 1995, which is usually not the desired result.

Note: You should always use roll and add rather than attempting to perform arithmetic operations directly on the fields of a Calendar. It is quite possible for Calendar subclasses to have fields with non-linear behavior, for example missing months or days during non-leap years. The subclasses' add and roll methods will take this into account, while simple arithmetic manipulations may give invalid results.

Parameters
field int: the calendar field to roll.
up boolean: indicates if the value of the specified time field is to be rolled up or rolled down. Use true if rolling up, false otherwise.
Throws
IllegalArgumentException if the field is invalid or refers to a field that cannot be handled by this method.

roll

Added in API level 24 
public void roll (int field, 
                int amount)

Rolls (up/down) a specified amount time on the given field. For example, to roll the current date up by three days, you can call roll(Calendar.DATE, 3). If the field is rolled past its maximum allowable value, it will "wrap" back to its minimum and continue rolling. For example, calling roll(Calendar.DATE, 10) on a Gregorian calendar set to 4/25/96 will result in the date 4/5/96.

When rolling on certain fields, the values of other fields may conflict and need to be changed. For example, when rolling the MONTH field for the Gregorian date 1/31/96 by +1, the DAY_OF_MONTH field must be adjusted so that the result is 2/29/96 rather than the invalid 2/31/96.

Rolling by a positive value always means rolling forward in time (unless the limit of the field is reached, in which case it may pin or wrap), so for the Gregorian calendar, starting with 100 BC and rolling the year by + 1 results in 99 BC. When eras have a definite beginning and end (as in the Chinese calendar, or as in most eras in the Japanese calendar) then rolling the year past either limit of the era will cause the year to wrap around. When eras only have a limit at one end, then attempting to roll the year past that limit will result in pinning the year at that limit. Note that for most calendars in which era 0 years move forward in time (such as Buddhist, Hebrew, or Islamic), it is possible for add or roll to result in negative years for era 0 (that is the only way to represent years before the calendar epoch in such calendars).

[icu] Note: the ICU implementation of this method is able to roll all fields except for ERA, DST_OFFSET, and ZONE_OFFSET. Subclasses may, of course, add support for additional fields in their overrides of roll.

Note: You should always use roll and add rather than attempting to perform arithmetic operations directly on the fields of a Calendar. It is quite possible for Calendar subclasses to have fields with non-linear behavior, for example missing months or days during non-leap years. The subclasses' add and roll methods will take this into account, while simple arithmetic manipulations may give invalid results.

Subclassing:
This implementation of roll assumes that the behavior of the field is continuous between its minimum and maximum, which are found by calling getActualMinimum and getActualMaximum. For most such fields, simple addition, subtraction, and modulus operations are sufficient to perform the roll. For week-related fields, the results of getFirstDayOfWeek and getMinimalDaysInFirstWeek are also necessary. Subclasses can override these two methods if their values differ from the defaults.

Subclasses that have fields for which the assumption of continuity breaks down must override roll to handle those fields specially. For example, in the Hebrew calendar the month "Adar I" only occurs in leap years; in other years the calendar jumps from Shevat (month #4) to Adar (month #6). The HebrewCalendar.roll method takes this into account, so that rolling the month of Shevat by one gives the proper result (Adar) in a non-leap year.

Parameters
field int: the calendar field to roll.
amount int: the amount by which the field should be rolled.
Throws
IllegalArgumentException if the field is invalid or refers to a field that cannot be handled by this method.

set

Added in API level 24 
public final void set (int year, 
                int month, 
                int date, 
                int hour, 
                int minute, 
                int second)

Sets the values for the fields year, month, date, hour, minute, and second. Previous values of other fields are retained. If this is not desired, call clear() first.

Parameters
year int: the value used to set the YEAR time field.
month int: the value used to set the MONTH time field. Month value is 0-based. e.g., 0 for January.
date int: the value used to set the DATE time field.
hour int: the value used to set the HOUR_OF_DAY time field.
minute int: the value used to set the MINUTE time field.
second int: the value used to set the SECOND time field.

set

Added in API level 24 
public final void set (int year, 
                int month, 
                int date, 
                int hour, 
                int minute)

Sets the values for the fields year, month, date, hour, and minute. Previous values of other fields are retained. If this is not desired, call clear() first.

Parameters
year int: the value used to set the YEAR time field.
month int: the value used to set the MONTH time field. Month value is 0-based. e.g., 0 for January.
date int: the value used to set the DATE time field.
hour int: the value used to set the HOUR_OF_DAY time field.
minute int: the value used to set the MINUTE time field.

set

Added in API level 24 
public final void set (int field, 
                int value)

Sets the time field with the given value.

Parameters
field int: the given time field.
value int: the value to be set for the given time field.

set

Added in API level 24 
public final void set (int year, 
                int month, 
                int date)

Sets the values for the fields year, month, and date. Previous values of other fields are retained. If this is not desired, call clear() first.

Parameters
year int: the value used to set the YEAR time field.
month int: the value used to set the MONTH time field. Month value is 0-based. e.g., 0 for January.
date int: the value used to set the DATE time field.

setFirstDayOfWeek

Added in API level 24 
public void setFirstDayOfWeek (int value)

Sets what the first day of the week is, where 1 = SUNDAY and 7 = SATURDAY.

Parameters
value int: the given first day of the week, where 1 = SUNDAY and 7 = SATURDAY.

setLenient

Added in API level 24 
public void setLenient (boolean lenient)

Specify whether or not date/time interpretation is to be lenient. With lenient interpretation, a date such as "February 942, 1996" will be treated as being equivalent to the 941st day after February 1, 1996. With strict interpretation, such dates will cause an exception to be thrown.

Parameters
lenient boolean

setMinimalDaysInFirstWeek

Added in API level 24 
public void setMinimalDaysInFirstWeek (int value)

Sets what the minimal days required in the first week of the year are. For example, if the first week is defined as one that contains the first day of the first month of a year, call the method with value 1. If it must be a full week, use value 7.

Parameters
value int: the given minimal days required in the first week of the year.

setRepeatedWallTimeOption

Added in API level 24 
public void setRepeatedWallTimeOption (int option)

[icu]Sets the behavior for handling wall time repeating multiple times at negative time zone offset transitions. For example, 1:30 AM on November 6, 2011 in US Eastern time (America/New_York) occurs twice; 1:30 AM EDT, then 1:30 AM EST one hour later. When WALLTIME_FIRST is used, the wall time 1:30AM in this example will be interpreted as 1:30 AM EDT (first occurrence). When WALLTIME_LAST is used, it will be interpreted as 1:30 AM EST (last occurrence). The default value is WALLTIME_LAST.

Parameters
option int: the behavior for handling repeating wall time, either WALLTIME_FIRST or WALLTIME_LAST.
Throws
IllegalArgumentException when option is neither WALLTIME_FIRST nor WALLTIME_LAST.

setSkippedWallTimeOption

Added in API level 24 
public void setSkippedWallTimeOption (int option)

[icu]Sets the behavior for handling skipped wall time at positive time zone offset transitions. For example, 2:30 AM on March 13, 2011 in US Eastern time (America/New_York) does not exist because the wall time jump from 1:59 AM EST to 3:00 AM EDT. When WALLTIME_FIRST is used, 2:30 AM is interpreted as 30 minutes before 3:00 AM EDT, therefore, it will be resolved as 1:30 AM EST. When WALLTIME_LAST is used, 2:30 AM is interpreted as 31 minutes after 1:59 AM EST, therefore, it will be resolved as 3:30 AM EDT. When WALLTIME_NEXT_VALID is used, 2:30 AM will be resolved as next valid wall time, that is 3:00 AM EDT. The default value is WALLTIME_LAST.

Note:This option is effective only when this calendar is lenient. When the calendar is strict, such non-existing wall time will cause an exception.

Parameters
option int: the behavior for handling skipped wall time at positive time zone offset transitions, one of WALLTIME_FIRST, WALLTIME_LAST and WALLTIME_NEXT_VALID.
Throws
IllegalArgumentException when option is not any of WALLTIME_FIRST, WALLTIME_LAST and WALLTIME_NEXT_VALID.

setTime

Added in API level 24 
public final void setTime (Date date)

Sets this Calendar's current time with the given Date.

Note: Calling setTime with Date(Long.MAX_VALUE) or Date(Long.MIN_VALUE) may yield incorrect field values from get(int).

Parameters
date Date: the given Date.

setTimeInMillis

Added in API level 24 
public void setTimeInMillis (long millis)

Sets this Calendar's current time from the given long value. An IllegalIcuArgumentException is thrown when millis is outside the range permitted by a Calendar object when in strict mode. When in lenient mode the out of range values are pinned to their respective min/max.

Parameters
millis long: the new time in UTC milliseconds from the epoch.

setTimeZone

Added in API level 24 
public void setTimeZone (TimeZone value)

Sets the time zone with the given time zone value.

Parameters
value TimeZone: the given time zone.

setWeekData

Added in API level 24 
public Calendar setWeekData (Calendar.WeekData wdata)

[icu] Set data in this calendar based on the WeekData input.

Parameters
wdata Calendar.WeekData: The week data to use
Returns
Calendar this, for chaining

toString

Added in API level 24 
public String toString ()

Returns a string representation of this calendar. This method is intended to be used only for debugging purposes, and the format of the returned string may vary between implementations. The returned string may be empty but may not be null.

Returns
String a string representation of this calendar.

Protected methods

complete

Added in API level 24 
protected void complete ()

Fills in any unset fields in the time field list.

computeFields

Added in API level 24 
protected void computeFields ()

Converts the current millisecond time value time to field values in fields[]. This synchronizes the time field values with a new time that is set for the calendar. The time is not recomputed first; to recompute the time, then the fields, call the complete method.

See also:

computeGregorianFields

Added in API level 24 
protected final void computeGregorianFields (int julianDay)

Compute the Gregorian calendar year, month, and day of month from the Julian day. These values are not stored in fields, but in member variables gregorianXxx. They are used for time zone computations and by subclasses that are Gregorian derivatives. Subclasses may call this method to perform a Gregorian calendar millis->fields computation. To perform a Gregorian calendar fields->millis computation, call computeGregorianMonthStart().

Parameters
julianDay int

computeGregorianMonthStart

Added in API level 24 
protected int computeGregorianMonthStart (int year, 
                int month)

Compute the Julian day of a month of the Gregorian calendar. Subclasses may call this method to perform a Gregorian calendar fields->millis computation. To perform a Gregorian calendar millis->fields computation, call computeGregorianFields().

Parameters
year int: extended Gregorian year
month int: zero-based Gregorian month
Returns
int the Julian day number of the day before the first day of the given month in the given extended year

computeJulianDay

Added in API level 24 
protected int computeJulianDay ()

Compute the Julian day number as specified by this calendar's fields.

Returns
int

computeMillisInDay

Added in API level 24
Deprecated in API level 26 
protected int computeMillisInDay ()

This method was deprecated in API level 26.
ICU 60

Compute the milliseconds in the day from the fields. This is a value from 0 to 23:59:59.999 inclusive, unless fields are out of range, in which case it can be an arbitrary value. This value reflects local zone wall time.

Returns
int

computeTime

Added in API level 24 
protected void computeTime ()

Converts the current field values in fields[] to the millisecond time value time.

computeZoneOffset

Added in API level 24
Deprecated in API level 26 
protected int computeZoneOffset (long millis, 
                int millisInDay)

This method was deprecated in API level 26.
ICU 60

This method can assume EXTENDED_YEAR has been set.

Parameters
millis long: milliseconds of the date fields (local midnight millis)
millisInDay int: milliseconds of the time fields; may be out or range.
Returns
int total zone offset (raw + DST) for the given moment

fieldName

Added in API level 24 
protected String fieldName (int field)

Returns a string name for a field, for debugging and exceptions.

Parameters
field int

Returns
String

floorDivide

Added in API level 24 
protected static final int floorDivide (int numerator, 
                int denominator, 
                int[] remainder)

Divide two integers, returning the floor of the quotient, and the modulus remainder.

Unlike the built-in division, this is mathematically well-behaved. E.g., -1/4 => 0 and -1%4 => -1, but floorDivide(-1,4) => -1 with remainder[0] => 3.

Parameters
numerator int: the numerator
denominator int: a divisor which must be > 0
remainder int: an array of at least one element in which the value numerator mod denominator is returned. Unlike numerator % denominator, this will always be non-negative.
Returns
int the floor of the quotient.

floorDivide

Added in API level 24 
protected static final int floorDivide (int numerator, 
                int denominator)

Divide two integers, returning the floor of the quotient.

Unlike the built-in division, this is mathematically well-behaved. E.g., -1/4 => 0 but floorDivide(-1,4) => -1.

Parameters
numerator int: the numerator
denominator int: a divisor which must be > 0
Returns
int the floor of the quotient.

floorDivide

Added in API level 24 
protected static final long floorDivide (long numerator, 
                long denominator)

Divide two long integers, returning the floor of the quotient.

Unlike the built-in division, this is mathematically well-behaved. E.g., -1/4 => 0 but floorDivide(-1,4) => -1.

Parameters
numerator long: the numerator
denominator long: a divisor which must be > 0
Returns
long the floor of the quotient.

floorDivide

Added in API level 24 
protected static final int floorDivide (long numerator, 
                int denominator, 
                int[] remainder)

Divide two integers, returning the floor of the quotient, and the modulus remainder.

Unlike the built-in division, this is mathematically well-behaved. E.g., -1/4 => 0 and -1%4 => -1, but floorDivide(-1,4) => -1 with remainder[0] => 3.

Parameters
numerator long: the numerator
denominator int: a divisor which must be > 0
remainder int: an array of at least one element in which the value numerator mod denominator is returned. Unlike numerator % denominator, this will always be non-negative.
Returns
int the floor of the quotient.

getFieldResolutionTable

Added in API level 24 
protected int[][][] getFieldResolutionTable ()

Returns the field resolution array for this calendar. Calendars that define additional fields or change the semantics of existing fields should override this method to adjust the field resolution semantics accordingly. Other subclasses should not override this method.

Returns
int[][][]

See also:

getGregorianDayOfMonth

Added in API level 24 
protected final int getGregorianDayOfMonth ()

Returns the day of month (1-based) on the Gregorian calendar as computed by computeGregorianFields().

Returns
int

getGregorianDayOfYear

Added in API level 24 
protected final int getGregorianDayOfYear ()

Returns the day of year (1-based) on the Gregorian calendar as computed by computeGregorianFields().

Returns
int

getGregorianMonth

Added in API level 24 
protected final int getGregorianMonth ()

Returns the month (0-based) on the Gregorian calendar as computed by computeGregorianFields().

Returns
int

getGregorianYear

Added in API level 24 
protected final int getGregorianYear ()

Returns the extended year on the Gregorian calendar as computed by computeGregorianFields().

Returns
int

getLimit

Added in API level 24 
protected int getLimit (int field, 
                int limitType)

Returns a limit for a field.

Parameters
field int: the field, from 0..getFieldCount()-1
limitType int: the type specifier for the limit
Returns
int

getStamp

Added in API level 24 
protected final int getStamp (int field)

Returns the timestamp of a field.

Parameters
field int

Returns
int

gregorianMonthLength

Added in API level 24 
protected static final int gregorianMonthLength (int y, 
                int m)

Returns the length of a month of the Gregorian calendar.

Parameters
y int: the extended year
m int: the 0-based month number
Returns
int the number of days in the given month

gregorianPreviousMonthLength

Added in API level 24 
protected static final int gregorianPreviousMonthLength (int y, 
                int m)

Returns the length of a previous month of the Gregorian calendar.

Parameters
y int: the extended year
m int: the 0-based month number
Returns
int the number of days in the month previous to the given month

handleComputeFields

Added in API level 24 
protected void handleComputeFields (int julianDay)

Subclasses may override this method to compute several fields specific to each calendar system. These are:

  • ERA
  • YEAR
  • MONTH
  • DAY_OF_MONTH
  • DAY_OF_YEAR
  • EXTENDED_YEAR
Subclasses can refer to the DAY_OF_WEEK and DOW_LOCAL fields, which will be set when this method is called. Subclasses can also call the getGregorianXxx() methods to obtain Gregorian calendar equivalents for the given Julian day.

In addition, subclasses should compute any subclass-specific fields, that is, fields from BASE_FIELD_COUNT to getFieldCount() - 1.

The default implementation in Calendar implements a pure proleptic Gregorian calendar.

Parameters
julianDay int

handleComputeJulianDay

Added in API level 24 
protected int handleComputeJulianDay (int bestField)

Subclasses may override this. This method calls handleGetMonthLength() to obtain the calendar-specific month length.

Parameters
bestField int

Returns
int

handleComputeMonthStart

Added in API level 24 
protected abstract int handleComputeMonthStart (int eyear, 
                int month, 
                boolean useMonth)

Returns the Julian day number of day before the first day of the given month in the given extended year. Subclasses should override this method to implement their calendar system.

Parameters
eyear int: the extended year
month int: the zero-based month, or 0 if useMonth is false
useMonth boolean: if false, compute the day before the first day of the given year, otherwise, compute the day before the first day of the given month
Returns
int the Julian day number of the day before the first day of the given month and year

handleCreateFields

Added in API level 24 
protected int[] handleCreateFields ()

Subclasses that use additional fields beyond those defined in Calendar should override this method to return an int[] array of the appropriate length. The length must be at least BASE_FIELD_COUNT and no more than MAX_FIELD_COUNT.

Returns
int[]

handleGetDateFormat

Added in API level 24 
protected DateFormat handleGetDateFormat (String pattern, 
                String override, 
                Locale locale)

Creates a DateFormat appropriate to this calendar. This is a framework method for subclasses to override. This method is responsible for creating the calendar-specific DateFormat and DateFormatSymbols objects as needed.

Parameters
pattern String: the pattern, specific to the DateFormat subclass
override String: The override string. A numbering system override string can take one of the following forms: 1). If just a numbering system name is specified, it applies to all numeric fields in the date format pattern. 2). To specify an alternate numbering system on a field by field basis, use the field letters from the pattern followed by an = sign, followed by the numbering system name. For example, to specify that just the year be formatted using Hebrew digits, use the override "y=hebr". Multiple overrides can be specified in a single string by separating them with a semi-colon. For example, the override string "m=thai;y=deva" would format using Thai digits for the month and Devanagari digits for the year.
locale Locale: the locale for which the symbols should be drawn
Returns
DateFormat a DateFormat appropriate to this calendar

handleGetDateFormat

Added in API level 24 
protected DateFormat handleGetDateFormat (String pattern, 
                ULocale locale)

Creates a DateFormat appropriate to this calendar. This is a framework method for subclasses to override. This method is responsible for creating the calendar-specific DateFormat and DateFormatSymbols objects as needed.

Parameters
pattern String: the pattern, specific to the DateFormat subclass
locale ULocale: the locale for which the symbols should be drawn
Returns
DateFormat a DateFormat appropriate to this calendar

handleGetDateFormat

Added in API level 24 
protected DateFormat handleGetDateFormat (String pattern, 
                Locale locale)

Creates a DateFormat appropriate to this calendar. This is a framework method for subclasses to override. This method is responsible for creating the calendar-specific DateFormat and DateFormatSymbols objects as needed.

Parameters
pattern String: the pattern, specific to the DateFormat subclass
locale Locale: the locale for which the symbols should be drawn
Returns
DateFormat a DateFormat appropriate to this calendar

handleGetExtendedYear

Added in API level 24 
protected abstract int handleGetExtendedYear ()

Returns the extended year defined by the current fields. This will use the EXTENDED_YEAR field or the YEAR and supra-year fields (such as ERA) specific to the calendar system, depending on which set of fields is newer.

Returns
int the extended year

handleGetLimit

Added in API level 24 
protected abstract int handleGetLimit (int field, 
                int limitType)

Subclass API for defining limits of different types. Subclasses must implement this method to return limits for the following fields: 

ERA
 YEAR
 MONTH
 WEEK_OF_YEAR
 WEEK_OF_MONTH
 DAY_OF_MONTH
 DAY_OF_YEAR
 DAY_OF_WEEK_IN_MONTH
 YEAR_WOY
 EXTENDED_YEAR

Parameters
field int: one of the above field numbers
limitType int: one of MINIMUM, GREATEST_MINIMUM, LEAST_MAXIMUM, or MAXIMUM
Returns
int

handleGetMonthLength

Added in API level 24 
protected int handleGetMonthLength (int extendedYear, 
                int month)

Returns the number of days in the given month of the given extended year of this calendar system. Subclasses should override this method if they can provide a more correct or more efficient implementation than the default implementation in Calendar.

Parameters
extendedYear int

month int

Returns
int

handleGetYearLength

Added in API level 24 
protected int handleGetYearLength (int eyear)

Returns the number of days in the given extended year of this calendar system. Subclasses should override this method if they can provide a more correct or more efficient implementation than the default implementation in Calendar.

Parameters
eyear int

Returns
int

internalGet

Added in API level 24 
protected final int internalGet (int field)

Returns the value for a given time field. This is an internal method for subclasses that does not trigger any calculations.

Parameters
field int: the given time field.
Returns
int the value for the given time field.

internalGet

Added in API level 24 
protected final int internalGet (int field, 
                int defaultValue)

Returns the value for a given time field, or return the given default value if the field is not set. This is an internal method for subclasses that does not trigger any calculations.

Parameters
field int: the given time field.
defaultValue int: value to return if field is not set
Returns
int the value for the given time field of defaultValue if the field is unset

internalGetTimeInMillis

Added in API level 24 
protected final long internalGetTimeInMillis ()

Returns the current milliseconds without recomputing.

Returns
long

internalSet

Added in API level 24 
protected final void internalSet (int field, 
                int value)

Set a field to a value. Subclasses should use this method when computing fields. It sets the time stamp in the stamp[] array to INTERNALLY_SET. If a field that may not be set by subclasses is passed in, an IllegalArgumentException is thrown. This prevents subclasses from modifying fields that are intended to be calendar-system invariant.

Parameters
field int

value int

isGregorianLeapYear

Added in API level 24 
protected static final boolean isGregorianLeapYear (int year)

Determines if the given year is a leap year. Returns true if the given year is a leap year.

Parameters
year int: the given year.
Returns
boolean true if the given year is a leap year; false otherwise.

julianDayToDayOfWeek

Added in API level 24 
protected static final int julianDayToDayOfWeek (int julian)

Returns the day of week, from SUNDAY to SATURDAY, given a Julian day.

Parameters
julian int

Returns
int

julianDayToMillis

Added in API level 24 
protected static final long julianDayToMillis (int julian)

Converts Julian day to time as milliseconds.

Parameters
julian int: the given Julian day number.
Returns
long time as milliseconds.

millisToJulianDay

Added in API level 24 
protected static final int millisToJulianDay (long millis)

Converts time as milliseconds to Julian day.

Parameters
millis long: the given milliseconds.
Returns
int the Julian day number.

newerField

Added in API level 24 
protected int newerField (int defaultField, 
                int alternateField)

Returns the field that is newer, either defaultField, or alternateField. If neither is newer or neither is set, return defaultField.

Parameters
defaultField int

alternateField int

Returns
int

newestStamp

Added in API level 24 
protected int newestStamp (int first, 
                int last, 
                int bestStampSoFar)

Returns the newest stamp of a given range of fields.

Parameters
first int

last int

bestStampSoFar int

Returns
int

pinField

Added in API level 24 
protected void pinField (int field)

Adjust the specified field so that it is within the allowable range for the date to which this calendar is set. For example, in a Gregorian calendar pinning the DAY_OF_MONTH field for a calendar set to April 31 would cause it to be set to April 30.

Subclassing:
This utility method is intended for use by subclasses that need to implement their own overrides of roll and add.

Note: pinField is implemented in terms of getActualMinimum and getActualMaximum. If either of those methods uses a slow, iterative algorithm for a particular field, it would be unwise to attempt to call pinField for that field. If you really do need to do so, you should override this method to do something more efficient for that field.

Parameters
field int: The calendar field whose value should be pinned.

prepareGetActual

Added in API level 24 
protected void prepareGetActual (int field, 
                boolean isMinimum)

Prepare this calendar for computing the actual minimum or maximum. This method modifies this calendar's fields; it is called on a temporary calendar.

Rationale: The semantics of getActualXxx() is to return the maximum or minimum value that the given field can take, taking into account other relevant fields. In general these other fields are larger fields. For example, when computing the actual maximum DAY_OF_MONTH, the current value of DAY_OF_MONTH itself is ignored, as is the value of any field smaller.

The time fields all have fixed minima and maxima, so we don't need to worry about them. This also lets us set the MILLISECONDS_IN_DAY to zero to erase any effects the time fields might have when computing date fields.

DAY_OF_WEEK is adjusted specially for the WEEK_OF_MONTH and WEEK_OF_YEAR fields to ensure that they are computed correctly.

Parameters
field int

isMinimum boolean

resolveFields

Added in API level 24 
protected int resolveFields (int[][][] precedenceTable)

Given a precedence table, return the newest field combination in the table, or -1 if none is found.

The precedence table is a 3-dimensional array of integers. It may be thought of as an array of groups. Each group is an array of lines. Each line is an array of field numbers. Within a line, if all fields are set, then the time stamp of the line is taken to be the stamp of the most recently set field. If any field of a line is unset, then the line fails to match. Within a group, the line with the newest time stamp is selected. The first field of the line is returned to indicate which line matched.

In some cases, it may be desirable to map a line to field that whose stamp is NOT examined. For example, if the best field is DAY_OF_WEEK then the DAY_OF_WEEK_IN_MONTH algorithm may be used. In order to do this, insert the value REMAP_RESOLVE | F at the start of the line, where F is the desired return field value. This field will NOT be examined; it only determines the return value if the other fields in the line are the newest.

If all lines of a group contain at least one unset field, then no line will match, and the group as a whole will fail to match. In that case, the next group will be processed. If all groups fail to match, then -1 is returned.

Parameters
precedenceTable int

Returns
int

validateField

Added in API level 24 
protected void validateField (int field)

Validate a single field of this calendar. Subclasses should override this method to validate any calendar-specific fields. Generic fields can be handled by Calendar.validateField().

Parameters
field int

validateField

Added in API level 24 
protected final void validateField (int field, 
                int min, 
                int max)

Validate a single field of this calendar given its minimum and maximum allowed value. If the field is out of range, throw a descriptive IllegalArgumentException. Subclasses may use this method in their implementation of validateField(int).

Parameters
field int

min int

max int

validateFields

Added in API level 24 
protected void validateFields ()

Ensure that each field is within its valid range by calling validateField(int) on each field that has been set. This method should only be called if this calendar is not lenient.

weekNumber

Added in API level 24 
protected int weekNumber (int desiredDay, 
                int dayOfPeriod, 
                int dayOfWeek)

Returns the week number of a day, within a period. This may be the week number in a year or the week number in a month. Usually this will be a value >= 1, but if some initial days of the period are excluded from week 1, because getMinimalDaysInFirstWeek is > 1, then the week number will be zero for those initial days. This method requires the day number and day of week for some known date in the period in order to determine the day of week on the desired day.

Subclassing:
This method is intended for use by subclasses in implementing their computeTime and/or computeFields methods. It is often useful in getActualMinimum and getActualMaximum as well.

This variant is handy for computing the week number of some other day of a period (often the first or last day of the period) when its day of the week is not known but the day number and day of week for some other day in the period (e.g. the current date) is known.

Parameters
desiredDay int: The DAY_OF_YEAR or DAY_OF_MONTH whose week number is desired. Should be 1 for the first day of the period.
dayOfPeriod int: The DAY_OF_YEAR or DAY_OF_MONTH for a day in the period whose DAY_OF_WEEK is specified by the dayOfWeek parameter. Should be 1 for first day of period.
dayOfWeek int: The DAY_OF_WEEK for the day corresponding to the dayOfPeriod parameter. 1-based with 1=Sunday.
Returns
int The week number (one-based), or zero if the day falls before the first week because getMinimalDaysInFirstWeek is more than one.

weekNumber

Added in API level 24 
protected final int weekNumber (int dayOfPeriod, 
                int dayOfWeek)

Returns the week number of a day, within a period. This may be the week number in a year, or the week number in a month. Usually this will be a value >= 1, but if some initial days of the period are excluded from week 1, because getMinimalDaysInFirstWeek is > 1, then the week number will be zero for those initial days. This method requires the day of week for the given date in order to determine the result.

Subclassing:
This method is intended for use by subclasses in implementing their computeTime and/or computeFields methods. It is often useful in getActualMinimum and getActualMaximum as well.

Parameters
dayOfPeriod int: The DAY_OF_YEAR or DAY_OF_MONTH whose week number is desired. Should be 1 for the first day of the period.
dayOfWeek int: The DAY_OF_WEEK for the day corresponding to the dayOfPeriod parameter. 1-based with 1=Sunday.
Returns
int The week number (one-based), or zero if the day falls before the first week because getMinimalDaysInFirstWeek is more than one.