Module java.base
Package java.util

Class Calendar

java.lang.Object
java.util.Calendar
All Implemented Interfaces:
Serializable, Cloneable, Comparable<Calendar>
Direct Known Subclasses:
GregorianCalendar
public abstract class Calendar extends Object implements Serializable, Cloneable, Comparable<Calendar>
The Calendar class is an abstract class that provides methods for converting between a specific instant in time and a set of calendar fields such as YEAR, MONTH, DAY_OF_MONTH, HOUR, and so on, and for manipulating the calendar fields, such as getting the date of the next week. An instant in time can be represented by a millisecond value that is an offset from the Epoch, January 1, 1970 00:00:00.000 GMT (Gregorian).

The class also provides additional fields and methods for implementing a concrete calendar system outside the package. Those fields and methods are defined as protected.

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 object whose calendar fields have been initialized with the current date and time: 

     Calendar rightNow = Calendar.getInstance();

A Calendar object can produce all the calendar 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 calendar fields, as well as their meaning. For example, the first month of the calendar system has value MONTH == JANUARY for all calendars. Other values are defined by the concrete subclass, such as ERA. See individual field documentation and subclass documentation for details.

Getting and Setting Calendar Field Values

The calendar field values can be set by calling the set methods. Any field values set in a Calendar will not be interpreted until it needs to calculate its time value (milliseconds from the Epoch) or values of the calendar fields. Calling the get, getTimeInMillis, getTime, add and roll involves such calculation.

Leniency

Calendar has two modes for interpreting the calendar fields, lenient and non-lenient. When a Calendar is in lenient mode, it accepts a wider range of calendar field values than it produces. When a Calendar recomputes calendar field values for return by get(), all of the calendar fields are normalized. For example, a lenient GregorianCalendar interprets MONTH == JANUARY, DAY_OF_MONTH == 32 as February 1.

When a Calendar is in non-lenient mode, it throws an exception if there is any inconsistency in its calendar fields. For example, a GregorianCalendar always produces DAY_OF_MONTH values between 1 and the length of the month. A non-lenient GregorianCalendar throws an exception upon calculating its time or calendar field values if any out-of-range field value has been set.

First Week

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 or the locale itself when a Calendar is constructed. If the designated locale contains "fw" and/or "rg" Unicode extensions, the first day of the week will be obtained according to those extensions. If both "fw" and "rg" are specified, the value from the "fw" extension supersedes the implicit one from the "rg" extension. They may also be specified explicitly through the methods for setting their values.

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.

Calendar Fields Resolution

When computing a date and time from the calendar fields, there may be insufficient information for the computation (such as only year and month with no day of month), or there may be inconsistent information (such as Tuesday, July 15, 1996 (Gregorian) -- July 15, 1996 is actually a Monday). Calendar will resolve calendar field values to determine the date and time in the following way.

If there is any conflict in calendar field values, Calendar gives priorities to calendar fields that have been set more recently. The following are the default combinations of the calendar fields. The most recent combination, as determined by the most recently set single field, will be used.

For the date fields: 

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

If there are any calendar fields whose values haven't been set in the selected field combination, Calendar uses their default values. The default value of each field may vary by concrete calendar systems. For example, in GregorianCalendar, the default of a field is the same as that of the start of the Epoch: i.e., YEAR = 1970, MONTH = JANUARY, DAY_OF_MONTH = 1, etc.

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

  1. 23:59 is the last minute of the day and 00:00 is the first minute of the next day. Thus, 23:59 on Dec 31, 1999 < 00:00 on Jan 1, 2000 < 00:01 on Jan 1, 2000.
  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

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

set(f, value) changes calendar field f to value. In addition, it sets an internal member variable to indicate that calendar field f has been changed. Although calendar field f is changed immediately, the calendar's time value in milliseconds is not recomputed until the next call to get(), getTime(), getTimeInMillis(), add(), or roll() is made. Thus, multiple calls to set() do not trigger multiple, unnecessary computations. As a result of changing a calendar field using set(), other calendar fields may also change, depending on the calendar field, the calendar field value, and the calendar system. In addition, get(f) will not necessarily return value set by the call to the set method after the calendar 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 date 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 date 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 or other constraints, such as time zone offset changes, 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: See GregorianCalendar.roll(int, int).

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.

Since:
1.1
See Also:
System.currentTimeMillis(), Date, GregorianCalendar, TimeZone, DateFormat, Serialized Form

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static class 
    Calendar.Builder
    Calendar.Builder is used for creating a Calendar from various date-time parameters.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static int
    ALL_STYLES
    A style specifier for getDisplayNames indicating names in all styles, such as "January" and "Jan".
    static int
    AM
    Value of the AM_PM field indicating the period of the day from midnight to just before noon.
    static int
    AM_PM
    Field number for get and set indicating whether the HOUR is before or after noon.
    static int
    APRIL
    Value of the MONTH field indicating the fourth month of the year in the Gregorian and Julian calendars.
    protected boolean
    areFieldsSet
    True if fields[] are in sync with the currently set time.
    static int
    AUGUST
    Value of the MONTH field indicating the eighth month of the year in the Gregorian and Julian calendars.
    static int
    DATE
    Field number for get and set indicating the day of the month.
    static int
    DAY_OF_MONTH
    Field number for get and set indicating the day of the month.
    static int
    DAY_OF_WEEK
    Field number for get and set indicating the day of the week.
    static 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.
    static int
    DAY_OF_YEAR
    Field number for get and set indicating the day number within the current year.
    static int
    DECEMBER
    Value of the MONTH field indicating the twelfth month of the year in the Gregorian and Julian calendars.
    static int
    DST_OFFSET
    Field number for get and set indicating the daylight saving offset in milliseconds.
    static int
    ERA
    Field number for get and set indicating the era, e.g., AD or BC in the Julian calendar.
    static int
    FEBRUARY
    Value of the MONTH field indicating the second month of the year in the Gregorian and Julian calendars.
    static int
    FIELD_COUNT
    The number of distinct fields recognized by get and set.
    protected int[]
    fields
    The calendar field values for the currently set time for this calendar.
    static int
    FRIDAY
    Value of the DAY_OF_WEEK field indicating Friday.
    static int
    HOUR
    Field number for get and set indicating the hour of the morning or afternoon.
    static int
    HOUR_OF_DAY
    Field number for get and set indicating the hour of the day.
    protected boolean[]
    isSet
    The flags which tell if a specified calendar field for the calendar is set.
    protected boolean
    isTimeSet
    True if then the value of time is valid.
    static int
    JANUARY
    Value of the MONTH field indicating the first month of the year in the Gregorian and Julian calendars.
    static int
    JULY
    Value of the MONTH field indicating the seventh month of the year in the Gregorian and Julian calendars.
    static int
    JUNE
    Value of the MONTH field indicating the sixth month of the year in the Gregorian and Julian calendars.
    static int
    LONG
    A style specifier for getDisplayName and getDisplayNames equivalent to LONG_FORMAT.
    static int
    LONG_FORMAT
    A style specifier for getDisplayName and getDisplayNames indicating a long name used for format.
    static int
    LONG_STANDALONE
    A style specifier for getDisplayName and getDisplayNames indicating a long name used independently, such as a month name as calendar headers.
    static int
    MARCH
    Value of the MONTH field indicating the third month of the year in the Gregorian and Julian calendars.
    static int
    MAY
    Value of the MONTH field indicating the fifth month of the year in the Gregorian and Julian calendars.
    static int
    MILLISECOND
    Field number for get and set indicating the millisecond within the second.
    static int
    MINUTE
    Field number for get and set indicating the minute within the hour.
    static int
    MONDAY
    Value of the DAY_OF_WEEK field indicating Monday.
    static int
    MONTH
    Field number for get and set indicating the month.
    static int
    NARROW_FORMAT
    A style specifier for getDisplayName and getDisplayNames indicating a narrow name used for format.
    static int
    NARROW_STANDALONE
    A style specifier for getDisplayName and getDisplayNames indicating a narrow name independently.
    static int
    NOVEMBER
    Value of the MONTH field indicating the eleventh month of the year in the Gregorian and Julian calendars.
    static int
    OCTOBER
    Value of the MONTH field indicating the tenth month of the year in the Gregorian and Julian calendars.
    static int
    PM
    Value of the AM_PM field indicating the period of the day from noon to just before midnight.
    static int
    SATURDAY
    Value of the DAY_OF_WEEK field indicating Saturday.
    static int
    SECOND
    Field number for get and set indicating the second within the minute.
    static int
    SEPTEMBER
    Value of the MONTH field indicating the ninth month of the year in the Gregorian and Julian calendars.
    static int
    SHORT
    A style specifier for getDisplayName and getDisplayNames equivalent to SHORT_FORMAT.
    static int
    SHORT_FORMAT
    A style specifier for getDisplayName and getDisplayNames indicating a short name used for format.
    static int
    SHORT_STANDALONE
    A style specifier for getDisplayName and getDisplayNames indicating a short name used independently, such as a month abbreviation as calendar headers.
    static int
    SUNDAY
    Value of the DAY_OF_WEEK field indicating Sunday.
    static int
    THURSDAY
    Value of the DAY_OF_WEEK field indicating Thursday.
    protected long
    time
    The currently set time for this calendar, expressed in milliseconds after January 1, 1970, 0:00:00 GMT.
    static int
    TUESDAY
    Value of the DAY_OF_WEEK field indicating Tuesday.
    static int
    UNDECIMBER
    Value of the MONTH field indicating the thirteenth month of the year.
    static int
    WEDNESDAY
    Value of the DAY_OF_WEEK field indicating Wednesday.
    static int
    WEEK_OF_MONTH
    Field number for get and set indicating the week number within the current month.
    static int
    WEEK_OF_YEAR
    Field number for get and set indicating the week number within the current year.
    static int
    YEAR
    Field number for get and set indicating the year.
    static int
    ZONE_OFFSET
    Field number for get and set indicating the raw offset from GMT in milliseconds.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    Calendar()
    Constructs a Calendar with the default time zone and the default FORMAT locale.
    protected
    Calendar​(TimeZone zone, Locale aLocale)
    Constructs a calendar with the specified time zone and locale.

  • Method Summary

    Modifier and Type
    Method
    Description
    abstract void
    add​(int field, int amount)
    Adds or subtracts the specified amount of time to the given calendar field, based on the calendar's rules.
    boolean
    after​(Object when)
    Returns whether this Calendar represents a time after the time represented by the specified Object.
    boolean
    before​(Object when)
    Returns whether this Calendar represents a time before the time represented by the specified Object.
    void
    clear()
    Sets all the calendar field values and the time value (millisecond offset from the Epoch) of this Calendar undefined.
    void
    clear​(int field)
    Sets the given calendar field value and the time value (millisecond offset from the Epoch) of this Calendar undefined.
    Object
    clone()
    Creates and returns a copy of this object.
    int
    compareTo​(Calendar anotherCalendar)
    Compares the time values (millisecond offsets from the Epoch) represented by two Calendar objects.
    protected void
    complete()
    Fills in any unset fields in the calendar fields.
    protected abstract void
    computeFields()
    Converts the current millisecond time value time to calendar field values in fields[].
    protected abstract void
    computeTime()
    Converts the current calendar field values in fields[] to the millisecond time value time.
    boolean
    equals​(Object obj)
    Compares this Calendar to the specified Object.
    int
    get​(int field)
    Returns the value of the given calendar field.
    int
    getActualMaximum​(int field)
    Returns the maximum value that the specified calendar field could have, given the time value of this Calendar.
    int
    getActualMinimum​(int field)
    Returns the minimum value that the specified calendar field could have, given the time value of this Calendar.
    static Set<String>
    getAvailableCalendarTypes()
    Returns an unmodifiable Set containing all calendar types supported by Calendar in the runtime environment.
    static Locale[]
    getAvailableLocales()
    Returns an array of all locales for which the getInstance methods of this class can return localized instances.
    String
    getCalendarType()
    Returns the calendar type of this Calendar.
    String
    getDisplayName​(int field, int style, Locale locale)
    Returns the string representation of the calendar field value in the given style and locale.
    Map<String,​Integer>
    getDisplayNames​(int field, int style, Locale locale)
    Returns a Map containing all names of the calendar field in the given style and locale and their corresponding field values.
    int
    getFirstDayOfWeek()
    Gets what the first day of the week is; e.g., SUNDAY in the U.S., MONDAY in France.
    abstract int
    getGreatestMinimum​(int field)
    Returns the highest minimum value for the given calendar field of this Calendar instance.
    static Calendar
    getInstance()
    Gets a calendar using the default time zone and locale.
    static Calendar
    getInstance​(Locale aLocale)
    Gets a calendar using the default time zone and specified locale.
    static Calendar
    getInstance​(TimeZone zone)
    Gets a calendar using the specified time zone and default locale.
    static Calendar
    getInstance​(TimeZone zone, Locale aLocale)
    Gets a calendar with the specified time zone and locale.
    abstract int
    getLeastMaximum​(int field)
    Returns the lowest maximum value for the given calendar field of this Calendar instance.
    abstract int
    getMaximum​(int field)
    Returns the maximum value for the given calendar field of this Calendar instance.
    int
    getMinimalDaysInFirstWeek()
    Gets what the minimal days required in the first week of the year are; e.g., if the first week is defined as one that contains the first day of the first month of a year, this method returns 1.
    abstract int
    getMinimum​(int field)
    Returns the minimum value for the given calendar field of this Calendar instance.
    Date
    getTime()
    Returns a Date object representing this Calendar's time value (millisecond offset from the Epoch").
    long
    getTimeInMillis()
    Returns this Calendar's time value in milliseconds.
    TimeZone
    getTimeZone()
    Gets the time zone.
    int
    getWeeksInWeekYear()
    Returns the number of weeks in the week year represented by this Calendar.
    int
    getWeekYear()
    Returns the week year represented by this Calendar.
    int
    hashCode()
    Returns a hash code for this calendar.
    protected int
    internalGet​(int field)
    Returns the value of the given calendar field.
    boolean
    isLenient()
    Tells whether date/time interpretation is to be lenient.
    boolean
    isSet​(int field)
    Determines if the given calendar field has a value set, including cases that the value has been set by internal fields calculations triggered by a get method call.
    boolean
    isWeekDateSupported()
    Returns whether this Calendar supports week dates.
    abstract void
    roll​(int field, boolean up)
    Adds or subtracts (up/down) a single unit of time on the given time field without changing larger fields.
    void
    roll​(int field, int amount)
    Adds the specified (signed) amount to the specified calendar field without changing larger fields.
    void
    set​(int field, int value)
    Sets the given calendar field to the given value.
    void
    set​(int year, int month, int date)
    Sets the values for the calendar fields YEAR, MONTH, and DAY_OF_MONTH.
    void
    set​(int year, int month, int date, int hourOfDay, int minute)
    Sets the values for the calendar fields YEAR, MONTH, DAY_OF_MONTH, HOUR_OF_DAY, and MINUTE.
    void
    set​(int year, int month, int date, int hourOfDay, int minute, int second)
    Sets the values for the fields YEAR, MONTH, DAY_OF_MONTH, HOUR_OF_DAY, MINUTE, and SECOND.
    void
    setFirstDayOfWeek​(int value)
    Sets what the first day of the week is; e.g., SUNDAY in the U.S., MONDAY in France.
    void
    setLenient​(boolean lenient)
    Specifies 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; For example, if the first week is defined as one that contains the first day of the first month of a year, call this method with value 1.
    void
    setTime​(Date date)
    Sets this Calendar's 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.
    void
    setWeekDate​(int weekYear, int weekOfYear, int dayOfWeek)
    Sets the date of this Calendar with the given date specifiers - week year, week of year, and day of week.
    Instant
    toInstant()
    Converts this object to an Instant.
    String
    toString()
    Return a string representation of this calendar.

    Methods declared in class java.lang.Object

    finalize, getClass, notify, notifyAll, wait, wait, wait

  • Field Details

    • ERA

      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.
      See Also:
      GregorianCalendar.AD, GregorianCalendar.BC, Constant Field Values

    • YEAR

      public static final int YEAR
      Field number for get and set indicating the year. This is a calendar-specific value; see subclass documentation.
      See Also:
      Constant Field Values

    • MONTH

      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 in the Gregorian and Julian calendars is JANUARY which is 0; the last depends on the number of months in a year.
      See Also:
      JANUARY, FEBRUARY, MARCH, APRIL, MAY, JUNE, JULY, AUGUST, SEPTEMBER, OCTOBER, NOVEMBER, DECEMBER, UNDECIMBER, Constant Field Values

    • WEEK_OF_YEAR

      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.
      See Also:
      getFirstDayOfWeek(), getMinimalDaysInFirstWeek(), Constant Field Values

    • WEEK_OF_MONTH

      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.
      See Also:
      getFirstDayOfWeek(), getMinimalDaysInFirstWeek(), Constant Field Values

    • DATE

      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:
      DAY_OF_MONTH, Constant Field Values

    • DAY_OF_MONTH

      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:
      DATE, Constant Field Values

    • DAY_OF_YEAR

      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.
      See Also:
      Constant Field Values

    • DAY_OF_WEEK

      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.
      See Also:
      SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, Constant Field Values

    • DAY_OF_WEEK_IN_MONTH

      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 14 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.
      See Also:
      DAY_OF_WEEK, WEEK_OF_MONTH, Constant Field Values

    • AM_PM

      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:
      AM, PM, HOUR, Constant Field Values

    • HOUR

      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 (0 - 11). Noon and midnight are represented by 0, not by 12. E.g., at 10:04:15.250 PM the HOUR is 10.
      See Also:
      AM_PM, HOUR_OF_DAY, Constant Field Values

    • HOUR_OF_DAY

      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:
      HOUR, Constant Field Values

    • MINUTE

      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.
      See Also:
      Constant Field Values

    • SECOND

      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.
      See Also:
      Constant Field Values

    • MILLISECOND

      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.
      See Also:
      Constant Field Values

    • ZONE_OFFSET

      public static final int ZONE_OFFSET
      Field number for get and set indicating the raw offset from GMT in milliseconds.

      This field reflects the correct GMT offset value of the time zone of this Calendar if the TimeZone implementation subclass supports historical GMT offset changes.

      See Also:
      Constant Field Values

    • DST_OFFSET

      public static final int DST_OFFSET
      Field number for get and set indicating the daylight saving offset in milliseconds.

      This field reflects the correct daylight saving offset value of the time zone of this Calendar if the TimeZone implementation subclass supports historical Daylight Saving Time schedule changes.

      See Also:
      Constant Field Values

    • FIELD_COUNT

      public static final int FIELD_COUNT
      The number of distinct fields recognized by get and set. Field numbers range from 0..FIELD_COUNT-1.
      See Also:
      Constant Field Values

    • SUNDAY

      public static final int SUNDAY
      Value of the DAY_OF_WEEK field indicating Sunday.
      See Also:
      Constant Field Values

    • MONDAY

      public static final int MONDAY
      Value of the DAY_OF_WEEK field indicating Monday.
      See Also:
      Constant Field Values

    • TUESDAY

      public static final int TUESDAY
      Value of the DAY_OF_WEEK field indicating Tuesday.
      See Also:
      Constant Field Values

    • WEDNESDAY

      public static final int WEDNESDAY
      Value of the DAY_OF_WEEK field indicating Wednesday.
      See Also:
      Constant Field Values

    • THURSDAY

      public static final int THURSDAY
      Value of the DAY_OF_WEEK field indicating Thursday.
      See Also:
      Constant Field Values

    • FRIDAY

      public static final int FRIDAY
      Value of the DAY_OF_WEEK field indicating Friday.
      See Also:
      Constant Field Values

    • SATURDAY

      public static final int SATURDAY
      Value of the DAY_OF_WEEK field indicating Saturday.
      See Also:
      Constant Field Values

    • JANUARY

      public static final int JANUARY
      Value of the MONTH field indicating the first month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • FEBRUARY

      public static final int FEBRUARY
      Value of the MONTH field indicating the second month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • MARCH

      public static final int MARCH
      Value of the MONTH field indicating the third month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • APRIL

      public static final int APRIL
      Value of the MONTH field indicating the fourth month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • MAY

      public static final int MAY
      Value of the MONTH field indicating the fifth month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • JUNE

      public static final int JUNE
      Value of the MONTH field indicating the sixth month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • JULY

      public static final int JULY
      Value of the MONTH field indicating the seventh month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • AUGUST

      public static final int AUGUST
      Value of the MONTH field indicating the eighth month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • SEPTEMBER

      public static final int SEPTEMBER
      Value of the MONTH field indicating the ninth month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • OCTOBER

      public static final int OCTOBER
      Value of the MONTH field indicating the tenth month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • NOVEMBER

      public static final int NOVEMBER
      Value of the MONTH field indicating the eleventh month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • DECEMBER

      public static final int DECEMBER
      Value of the MONTH field indicating the twelfth month of the year in the Gregorian and Julian calendars.
      See Also:
      Constant Field Values

    • UNDECIMBER

      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.
      See Also:
      Constant Field Values

    • AM

      public static final int AM
      Value of the AM_PM field indicating the period of the day from midnight to just before noon.
      See Also:
      Constant Field Values

    • PM

      public static final int PM
      Value of the AM_PM field indicating the period of the day from noon to just before midnight.
      See Also:
      Constant Field Values

    • ALL_STYLES

      public static final int ALL_STYLES
      A style specifier for getDisplayNames indicating names in all styles, such as "January" and "Jan".
      Since:
      1.6
      See Also:
      SHORT_FORMAT, LONG_FORMAT, SHORT_STANDALONE, LONG_STANDALONE, SHORT, LONG, Constant Field Values

    • SHORT

      public static final int SHORT
      A style specifier for getDisplayName and getDisplayNames equivalent to SHORT_FORMAT.
      Since:
      1.6
      See Also:
      SHORT_STANDALONE, LONG, Constant Field Values

    • LONG

      public static final int LONG
      A style specifier for getDisplayName and getDisplayNames equivalent to LONG_FORMAT.
      Since:
      1.6
      See Also:
      LONG_STANDALONE, SHORT, Constant Field Values

    • NARROW_FORMAT

      public static final int NARROW_FORMAT
      A style specifier for getDisplayName and getDisplayNames indicating a narrow name used for format. Narrow names are typically single character strings, such as "M" for Monday.
      Since:
      1.8
      See Also:
      NARROW_STANDALONE, SHORT_FORMAT, LONG_FORMAT, Constant Field Values

    • NARROW_STANDALONE

      public static final int NARROW_STANDALONE
      A style specifier for getDisplayName and getDisplayNames indicating a narrow name independently. Narrow names are typically single character strings, such as "M" for Monday.
      Since:
      1.8
      See Also:
      NARROW_FORMAT, SHORT_STANDALONE, LONG_STANDALONE, Constant Field Values

    • SHORT_FORMAT

      public static final int SHORT_FORMAT
      A style specifier for getDisplayName and getDisplayNames indicating a short name used for format.
      Since:
      1.8
      See Also:
      SHORT_STANDALONE, LONG_FORMAT, LONG_STANDALONE, Constant Field Values

    • LONG_FORMAT

      public static final int LONG_FORMAT
      A style specifier for getDisplayName and getDisplayNames indicating a long name used for format.
      Since:
      1.8
      See Also:
      LONG_STANDALONE, SHORT_FORMAT, SHORT_STANDALONE, Constant Field Values

    • SHORT_STANDALONE

      public static final int SHORT_STANDALONE
      A style specifier for getDisplayName and getDisplayNames indicating a short name used independently, such as a month abbreviation as calendar headers.
      Since:
      1.8
      See Also:
      SHORT_FORMAT, LONG_FORMAT, LONG_STANDALONE, Constant Field Values

    • LONG_STANDALONE

      public static final int LONG_STANDALONE
      A style specifier for getDisplayName and getDisplayNames indicating a long name used independently, such as a month name as calendar headers.
      Since:
      1.8
      See Also:
      LONG_FORMAT, SHORT_FORMAT, SHORT_STANDALONE, Constant Field Values

    • fields

      protected int[] fields
      The calendar field values for the currently set time for this calendar. This is an array of FIELD_COUNT integers, with index values ERA through DST_OFFSET.

    • isSet

      protected boolean[] isSet
      The flags which tell if a specified calendar field for the calendar is set. A new object has no fields set. After the first call to a method which generates the fields, they all remain set after that. This is an array of FIELD_COUNT booleans, with index values ERA through DST_OFFSET.

    • time

      protected long time
      The currently set time for this calendar, expressed in milliseconds after January 1, 1970, 0:00:00 GMT.
      See Also:
      isTimeSet

    • isTimeSet

      protected boolean isTimeSet
      True if then the value of time is valid. The time is made invalid by a change to an item of field[].
      See Also:
      time

    • areFieldsSet

      protected boolean areFieldsSet
      True if fields[] are in sync with the currently set time. If false, then the next attempt to get the value of a field will force a recomputation of all fields from the current value of time.

  • Constructor Details

    • Calendar

      protected Calendar()
      Constructs a Calendar with the default time zone and the default FORMAT locale.
      See Also:
      TimeZone.getDefault()

    • Calendar

      protected Calendar​(TimeZone zone, Locale aLocale)
      Constructs a calendar with the specified time zone and locale.
      Parameters:
      zone - the time zone to use
      aLocale - the locale for the week data

  • Method Details

    • getInstance

      public static Calendar getInstance()
      Gets a calendar using the default time zone and locale. The Calendar returned is based on the current time in the default time zone with the default FORMAT locale.

      If the locale contains the time zone with "tz" Unicode extension, that time zone is used instead.

      Returns:
      a Calendar.

    • getInstance

      public static Calendar getInstance​(TimeZone zone)
      Gets a calendar using the specified time zone and default locale. The Calendar returned is based on the current time in the given time zone with the default FORMAT locale.
      Parameters:
      zone - the time zone to use
      Returns:
      a Calendar.

    • getInstance

      public static Calendar getInstance​(Locale aLocale)
      Gets a calendar using the default time zone and specified locale. The Calendar returned is based on the current time in the default time zone with the given locale.

      If the locale contains the time zone with "tz" Unicode extension, that time zone is used instead.

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

    • getInstance

      public static Calendar getInstance​(TimeZone zone, Locale aLocale)
      Gets a calendar with the specified time zone and locale. The Calendar returned is based on the current time in the given time zone with the given locale.
      Parameters:
      zone - the time zone to use
      aLocale - the locale for the week data
      Returns:
      a Calendar.

    • getAvailableLocales

      public static Locale[] getAvailableLocales()
      Returns an array of all locales for which the getInstance methods of this class can return localized instances. The array returned must contain at least a Locale instance equal to Locale.US.
      Returns:
      An array of locales for which localized Calendar instances are available.

    • computeTime

      protected abstract void computeTime()
      Converts the current calendar field values in fields[] to the millisecond time value time.
      See Also:
      complete(), computeFields()

    • computeFields

      protected abstract void computeFields()
      Converts the current millisecond time value time to calendar field values in fields[]. This allows you to sync up the calendar 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:
      computeTime()

    • getTime

      public final Date getTime()
      Returns a Date object representing this Calendar's time value (millisecond offset from the Epoch").
      Returns:
      a Date representing the time value.
      See Also:
      setTime(Date), getTimeInMillis()

    • setTime

      public final void setTime​(Date date)
      Sets this Calendar's 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().

      Parameters:
      date - the given Date.
      Throws:
      NullPointerException - if date is null
      See Also:
      getTime(), setTimeInMillis(long)

    • getTimeInMillis

      public long getTimeInMillis()
      Returns this Calendar's time value in milliseconds.
      Returns:
      the current time as UTC milliseconds from the epoch.
      See Also:
      getTime(), setTimeInMillis(long)

    • setTimeInMillis

      public void setTimeInMillis​(long millis)
      Sets this Calendar's current time from the given long value.
      Parameters:
      millis - the new time in UTC milliseconds from the epoch.
      See Also:
      setTime(Date), getTimeInMillis()

    • get

      public int get​(int field)
      Returns the value of the given calendar field. In lenient mode, all calendar fields are normalized. In non-lenient mode, all calendar fields are validated and this method throws an exception if any calendar fields have out-of-range values. The normalization and validation are handled by the complete() method, which process is calendar system dependent.
      Parameters:
      field - the given calendar field.
      Returns:
      the value for the given calendar field.
      Throws:
      ArrayIndexOutOfBoundsException - if the specified field is out of range (field < 0 || field >= FIELD_COUNT).
      See Also:
      set(int,int), complete()

    • internalGet

      protected final int internalGet​(int field)
      Returns the value of the given calendar field. This method does not involve normalization or validation of the field value.
      Parameters:
      field - the given calendar field.
      Returns:
      the value for the given calendar field.
      See Also:
      get(int)

    • set

      public void set​(int field, int value)
      Sets the given calendar field to the given value. The value is not interpreted by this method regardless of the leniency mode.
      Parameters:
      field - the given calendar field.
      value - the value to be set for the given calendar field.
      Throws:
      ArrayIndexOutOfBoundsException - if the specified field is out of range (field < 0 || field >= FIELD_COUNT). in non-lenient mode.
      See Also:
      set(int,int,int), set(int,int,int,int,int), set(int,int,int,int,int,int), get(int)

    • set

      public final void set​(int year, int month, int date)
      Sets the values for the calendar fields YEAR, MONTH, and DAY_OF_MONTH. Previous values of other calendar fields are retained. If this is not desired, call clear() first.
      Parameters:
      year - the value used to set the YEAR calendar field.
      month - the value used to set the MONTH calendar field. Month value is 0-based. e.g., 0 for January.
      date - the value used to set the DAY_OF_MONTH calendar field.
      See Also:
      set(int,int), set(int,int,int,int,int), set(int,int,int,int,int,int)

    • set

      public final void set​(int year, int month, int date, int hourOfDay, int minute)
      Sets the values for the calendar fields YEAR, MONTH, DAY_OF_MONTH, HOUR_OF_DAY, and MINUTE. Previous values of other fields are retained. If this is not desired, call clear() first.
      Parameters:
      year - the value used to set the YEAR calendar field.
      month - the value used to set the MONTH calendar field. Month value is 0-based. e.g., 0 for January.
      date - the value used to set the DAY_OF_MONTH calendar field.
      hourOfDay - the value used to set the HOUR_OF_DAY calendar field.
      minute - the value used to set the MINUTE calendar field.
      See Also:
      set(int,int), set(int,int,int), set(int,int,int,int,int,int)

    • set

      public final void set​(int year, int month, int date, int hourOfDay, int minute, int second)
      Sets the values for the fields YEAR, MONTH, DAY_OF_MONTH, HOUR_OF_DAY, MINUTE, and SECOND. Previous values of other fields are retained. If this is not desired, call clear() first.
      Parameters:
      year - the value used to set the YEAR calendar field.
      month - the value used to set the MONTH calendar field. Month value is 0-based. e.g., 0 for January.
      date - the value used to set the DAY_OF_MONTH calendar field.
      hourOfDay - the value used to set the HOUR_OF_DAY calendar field.
      minute - the value used to set the MINUTE calendar field.
      second - the value used to set the SECOND calendar field.
      See Also:
      set(int,int), set(int,int,int), set(int,int,int,int,int)

    • clear

      public final void clear()
      Sets all the calendar field values and the time value (millisecond offset from the Epoch) of this Calendar undefined. This means that isSet() will return false for all the calendar fields, and the date and time calculations will treat the fields as if they had never been set. A Calendar implementation class may use its specific default field values for date/time calculations. For example, GregorianCalendar uses 1970 if the YEAR field value is undefined.
      See Also:
      clear(int)

    • clear

      public final void clear​(int field)
      Sets the given calendar field value and the time value (millisecond offset from the Epoch) of this Calendar undefined. This means that isSet(field) will return false, and the date and time calculations will treat the field as if it had never been set. A Calendar implementation class may use the field's specific default value for date and time calculations.

      The HOUR_OF_DAY, HOUR and AM_PM fields are handled independently and the the resolution rule for the time of day is applied. Clearing one of the fields doesn't reset the hour of day value of this Calendar. Use set(Calendar.HOUR_OF_DAY, 0) to reset the hour value.

      Parameters:
      field - the calendar field to be cleared.
      See Also:
      clear()

    • isSet

      public final boolean isSet​(int field)
      Determines if the given calendar field has a value set, including cases that the value has been set by internal fields calculations triggered by a get method call.
      Parameters:
      field - the calendar field to test
      Returns:
      true if the given calendar field has a value set; false otherwise.

    • getDisplayName

      public String getDisplayName​(int field, int style, Locale locale)
      Returns the string representation of the calendar field value in the given style and locale. If no string representation is applicable, null is returned. This method calls get(field) to get the calendar field value if the string representation is applicable to the given calendar field.

      For example, if this Calendar is a GregorianCalendar and its date is 2005-01-01, then the string representation of the MONTH field would be "January" in the long style in an English locale or "Jan" in the short style. However, no string representation would be available for the DAY_OF_MONTH field, and this method would return null.

      The default implementation supports the calendar fields for which a DateFormatSymbols has names in the given locale.

      Parameters:
      field - the calendar field for which the string representation is returned
      style - the style applied to the string representation; one of SHORT_FORMAT (SHORT), SHORT_STANDALONE, LONG_FORMAT (LONG), LONG_STANDALONE, NARROW_FORMAT, or NARROW_STANDALONE.
      locale - the locale for the string representation (any calendar types specified by locale are ignored)
      Returns:
      the string representation of the given field in the given style, or null if no string representation is applicable.
      Throws:
      IllegalArgumentException - if field or style is invalid, or if this Calendar is non-lenient and any of the calendar fields have invalid values
      NullPointerException - if locale is null
      Since:
      1.6

    • getDisplayNames

      public Map<String,​Integer> getDisplayNames​(int field, int style, Locale locale)
      Returns a Map containing all names of the calendar field in the given style and locale and their corresponding field values. For example, if this Calendar is a GregorianCalendar, the returned map would contain "Jan" to JANUARY, "Feb" to FEBRUARY, and so on, in the short style in an English locale.

      Narrow names may not be unique due to use of single characters, such as "S" for Sunday and Saturday. In that case narrow names are not included in the returned Map.

      The values of other calendar fields may be taken into account to determine a set of display names. For example, if this Calendar is a lunisolar calendar system and the year value given by the YEAR field has a leap month, this method would return month names containing the leap month name, and month names are mapped to their values specific for the year.

      The default implementation supports display names contained in a DateFormatSymbols. For example, if field is MONTH and style is ALL_STYLES, this method returns a Map containing all strings returned by DateFormatSymbols.getShortMonths() and DateFormatSymbols.getMonths().

      Parameters:
      field - the calendar field for which the display names are returned
      style - the style applied to the string representation; one of SHORT_FORMAT (SHORT), SHORT_STANDALONE, LONG_FORMAT (LONG), LONG_STANDALONE, NARROW_FORMAT, or NARROW_STANDALONE
      locale - the locale for the display names
      Returns:
      a Map containing all display names in style and locale and their field values, or null if no display names are defined for field
      Throws:
      IllegalArgumentException - if field or style is invalid, or if this Calendar is non-lenient and any of the calendar fields have invalid values
      NullPointerException - if locale is null
      Since:
      1.6

    • complete

      protected void complete()
      Fills in any unset fields in the calendar fields. First, the computeTime() method is called if the time value (millisecond offset from the Epoch) has not been calculated from calendar field values. Then, the computeFields() method is called to calculate all calendar field values.

    • getAvailableCalendarTypes

      public static Set<String> getAvailableCalendarTypes()
      Returns an unmodifiable Set containing all calendar types supported by Calendar in the runtime environment. The available calendar types can be used for the Unicode locale extensions. The Set returned contains at least "gregory". The calendar types don't include aliases, such as "gregorian" for "gregory".
      Returns:
      an unmodifiable Set containing all available calendar types
      Since:
      1.8
      See Also:
      getCalendarType(), Calendar.Builder.setCalendarType(String), Locale.getUnicodeLocaleType(String)

    • getCalendarType

      public String getCalendarType()
      Returns the calendar type of this Calendar. Calendar types are defined by the Unicode Locale Data Markup Language (LDML) specification.

      The default implementation of this method returns the class name of this Calendar instance. Any subclasses that implement LDML-defined calendar systems should override this method to return appropriate calendar types.

      Returns:
      the LDML-defined calendar type or the class name of this Calendar instance
      Since:
      1.8
      See Also:
      Locale extensions, Locale.Builder.setLocale(Locale), Locale.Builder.setUnicodeLocaleKeyword(String, String)

    • equals

      public boolean equals​(Object obj)
      Compares this Calendar to the specified Object. The result is true if and only if the argument is a Calendar object of the same calendar system that represents the same time value (millisecond offset from the Epoch) under the same Calendar parameters as this object.

      The Calendar parameters are the values represented by the isLenient, getFirstDayOfWeek, getMinimalDaysInFirstWeek and getTimeZone methods. If there is any difference in those parameters between the two Calendars, this method returns false.

      Use the compareTo method to compare only the time values.

      Overrides:
      equals in class Object
      Parameters:
      obj - the object to compare with.
      Returns:
      true if this object is equal to obj; false otherwise.
      See Also:
      Object.hashCode(), HashMap

    • hashCode

      public int hashCode()
      Returns a hash code for this calendar.
      Overrides:
      hashCode in class Object
      Returns:
      a hash code value for this object.
      Since:
      1.2
      See Also:
      Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

    • before

      public boolean before​(Object when)
      Returns whether this Calendar represents a time before the time represented by the specified Object. This method is equivalent to: 
      
         compareTo(when) < 0
      if and only if when is a Calendar instance. Otherwise, the method returns false.
      Parameters:
      when - the Object to be compared
      Returns:
      true if the time of this Calendar is before the time represented by when; false otherwise.
      See Also:
      compareTo(Calendar)

    • after

      public boolean after​(Object when)
      Returns whether this Calendar represents a time after the time represented by the specified Object. This method is equivalent to: 
      
         compareTo(when) > 0
      if and only if when is a Calendar instance. Otherwise, the method returns false.
      Parameters:
      when - the Object to be compared
      Returns:
      true if the time of this Calendar is after the time represented by when; false otherwise.
      See Also:
      compareTo(Calendar)

    • compareTo

      public int compareTo​(Calendar anotherCalendar)
      Compares the time values (millisecond offsets from the Epoch) represented by two Calendar objects.
      Specified by:
      compareTo in interface Comparable<Calendar>
      Parameters:
      anotherCalendar - the Calendar to be compared.
      Returns:
      the value 0 if the time represented by the argument is equal to the time represented by this Calendar; a value less than 0 if the time of this Calendar is before the time represented by the argument; and a value greater than 0 if the time of this Calendar is after the time represented by the argument.
      Throws:
      NullPointerException - if the specified Calendar is null.
      IllegalArgumentException - if the time value of the specified Calendar object can't be obtained due to any invalid calendar values.
      Since:
      1.5

    • add

      public abstract void add​(int field, int amount)
      Adds or subtracts the specified amount of time to the given calendar field, based on the calendar's rules. For example, to subtract 5 days from the current time of the calendar, you can achieve it by calling:

      add(Calendar.DAY_OF_MONTH, -5).

      Parameters:
      field - the calendar field.
      amount - the amount of date or time to be added to the field.
      See Also:
      roll(int,int), set(int,int)

    • roll

      public abstract void roll​(int field, boolean up)
      Adds or subtracts (up/down) a single unit of time on the given time field without changing larger fields. For example, to roll the current date up by one day, you can achieve it by calling:

      roll(Calendar.DATE, true). When rolling on the year or Calendar.YEAR field, it will roll the year value in the range between 1 and the value returned by calling getMaximum(Calendar.YEAR). When rolling on the month or Calendar.MONTH field, other fields like date might conflict and, need to be changed. For instance, rolling the month on the date 01/31/96 will result in 02/29/96. When rolling on the hour-in-day or Calendar.HOUR_OF_DAY field, it will roll the hour value in the range between 0 and 23, which is zero-based.

      Parameters:
      field - the time field.
      up - indicates if the value of the specified time field is to be rolled up or rolled down. Use true if rolling up, false otherwise.
      See Also:
      add(int,int), set(int,int)

    • roll

      public void roll​(int field, int amount)
      Adds the specified (signed) amount to the specified calendar field without changing larger fields. A negative amount means to roll down.

      NOTE: This default implementation on Calendar just repeatedly calls the version of roll() that rolls by one unit. This may not always do the right thing. For example, if the DAY_OF_MONTH field is 31, rolling through February will leave it set to 28. The GregorianCalendar version of this function takes care of this problem. Other subclasses should also provide overrides of this function that do the right thing.

      Parameters:
      field - the calendar field.
      amount - the signed amount to add to the calendar field.
      Since:
      1.2
      See Also:
      roll(int,boolean), add(int,int), set(int,int)

    • setTimeZone

      public void setTimeZone​(TimeZone value)
      Sets the time zone with the given time zone value.
      Parameters:
      value - the given time zone.

    • getTimeZone

      public TimeZone getTimeZone()
      Gets the time zone.
      Returns:
      the time zone object associated with this calendar.

    • setLenient

      public void setLenient​(boolean lenient)
      Specifies 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 (non-lenient) interpretation, such dates will cause an exception to be thrown. The default is lenient.
      Parameters:
      lenient - true if the lenient mode is to be turned on; false if it is to be turned off.
      See Also:
      isLenient(), DateFormat.setLenient(boolean)

    • isLenient

      public boolean isLenient()
      Tells whether date/time interpretation is to be lenient.
      Returns:
      true if the interpretation mode of this calendar is lenient; false otherwise.
      See Also:
      setLenient(boolean)

    • setFirstDayOfWeek

      public void setFirstDayOfWeek​(int value)
      Sets what the first day of the week is; e.g., SUNDAY in the U.S., MONDAY in France.
      Parameters:
      value - the given first day of the week.
      See Also:
      getFirstDayOfWeek(), getMinimalDaysInFirstWeek()

    • getFirstDayOfWeek

      public int getFirstDayOfWeek()
      Gets what the first day of the week is; e.g., SUNDAY in the U.S., MONDAY in France.
      Returns:
      the first day of the week.
      See Also:
      setFirstDayOfWeek(int), getMinimalDaysInFirstWeek()

    • setMinimalDaysInFirstWeek

      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 this method with value 1. If it must be a full week, use value 7.
      Parameters:
      value - the given minimal days required in the first week of the year.
      See Also:
      getMinimalDaysInFirstWeek()

    • getMinimalDaysInFirstWeek

      public int getMinimalDaysInFirstWeek()
      Gets what the minimal days required in the first week of the year are; e.g., if the first week is defined as one that contains the first day of the first month of a year, this method returns 1. If the minimal days required must be a full week, this method returns 7.
      Returns:
      the minimal days required in the first week of the year.
      See Also:
      setMinimalDaysInFirstWeek(int)

    • isWeekDateSupported

      public boolean isWeekDateSupported()
      Returns whether this Calendar supports week dates.

      The default implementation of this method returns false.

      Returns:
      true if this Calendar supports week dates; false otherwise.
      Since:
      1.7
      See Also:
      getWeekYear(), setWeekDate(int,int,int), getWeeksInWeekYear()

    • getWeekYear

      public int getWeekYear()
      Returns the week year represented by this Calendar. The week year is in sync with the week cycle. The first day of the first week is the first day of the week year.

      The default implementation of this method throws an UnsupportedOperationException.

      Returns:
      the week year of this Calendar
      Throws:
      UnsupportedOperationException - if any week year numbering isn't supported in this Calendar.
      Since:
      1.7
      See Also:
      isWeekDateSupported(), getFirstDayOfWeek(), getMinimalDaysInFirstWeek()

    • setWeekDate

      public void setWeekDate​(int weekYear, int weekOfYear, int dayOfWeek)
      Sets the date of this Calendar with the given date specifiers - week year, week of year, and day of week.

      Unlike the set method, all of the calendar fields and time values are calculated upon return.

      If weekOfYear is out of the valid week-of-year range in weekYear, the weekYear and weekOfYear values are adjusted in lenient mode, or an IllegalArgumentException is thrown in non-lenient mode.

      The default implementation of this method throws an UnsupportedOperationException.

      Parameters:
      weekYear - the week year
      weekOfYear - the week number based on weekYear
      dayOfWeek - the day of week value: one of the constants for the DAY_OF_WEEK field: SUNDAY, ..., SATURDAY.
      Throws:
      IllegalArgumentException - if any of the given date specifiers is invalid or any of the calendar fields are inconsistent with the given date specifiers in non-lenient mode
      UnsupportedOperationException - if any week year numbering isn't supported in this Calendar.
      Since:
      1.7
      See Also:
      isWeekDateSupported(), getFirstDayOfWeek(), getMinimalDaysInFirstWeek()

    • getWeeksInWeekYear

      public int getWeeksInWeekYear()
      Returns the number of weeks in the week year represented by this Calendar.

      The default implementation of this method throws an UnsupportedOperationException.

      Returns:
      the number of weeks in the week year.
      Throws:
      UnsupportedOperationException - if any week year numbering isn't supported in this Calendar.
      Since:
      1.7
      See Also:
      WEEK_OF_YEAR, isWeekDateSupported(), getWeekYear(), getActualMaximum(int)

    • getMinimum

      public abstract int getMinimum​(int field)
      Returns the minimum value for the given calendar field of this Calendar instance. The minimum value is defined as the smallest value returned by the get method for any possible time value. The minimum value depends on calendar system specific parameters of the instance.
      Parameters:
      field - the calendar field.
      Returns:
      the minimum value for the given calendar field.
      See Also:
      getMaximum(int), getGreatestMinimum(int), getLeastMaximum(int), getActualMinimum(int), getActualMaximum(int)

    • getMaximum

      public abstract int getMaximum​(int field)
      Returns the maximum value for the given calendar field of this Calendar instance. The maximum value is defined as the largest value returned by the get method for any possible time value. The maximum value depends on calendar system specific parameters of the instance.
      Parameters:
      field - the calendar field.
      Returns:
      the maximum value for the given calendar field.
      See Also:
      getMinimum(int), getGreatestMinimum(int), getLeastMaximum(int), getActualMinimum(int), getActualMaximum(int)

    • getGreatestMinimum

      public abstract int getGreatestMinimum​(int field)
      Returns the highest minimum value for the given calendar field of this Calendar instance. The highest minimum value is defined as the largest value returned by getActualMinimum(int) for any possible time value. The greatest minimum value depends on calendar system specific parameters of the instance.
      Parameters:
      field - the calendar field.
      Returns:
      the highest minimum value for the given calendar field.
      See Also:
      getMinimum(int), getMaximum(int), getLeastMaximum(int), getActualMinimum(int), getActualMaximum(int)

    • getLeastMaximum

      public abstract int getLeastMaximum​(int field)
      Returns the lowest maximum value for the given calendar field of this Calendar instance. The lowest maximum value is defined as the smallest value returned by getActualMaximum(int) for any possible time value. The least maximum value depends on calendar system specific parameters of the instance. For example, a Calendar for the Gregorian calendar system returns 28 for the DAY_OF_MONTH field, because the 28th is the last day of the shortest month of this calendar, February in a common year.
      Parameters:
      field - the calendar field.
      Returns:
      the lowest maximum value for the given calendar field.
      See Also:
      getMinimum(int), getMaximum(int), getGreatestMinimum(int), getActualMinimum(int), getActualMaximum(int)

    • getActualMinimum

      public int getActualMinimum​(int field)
      Returns the minimum value that the specified calendar field could have, given the time value of this Calendar.

      The default implementation of this method uses an iterative algorithm to determine the actual minimum value for the calendar field. Subclasses should, if possible, override this with a more efficient implementation - in many cases, they can simply return getMinimum().

      Parameters:
      field - the calendar field
      Returns:
      the minimum of the given calendar field for the time value of this Calendar
      Since:
      1.2
      See Also:
      getMinimum(int), getMaximum(int), getGreatestMinimum(int), getLeastMaximum(int), getActualMaximum(int)

    • getActualMaximum

      public int getActualMaximum​(int field)
      Returns the maximum value that the specified calendar field could have, given the time value of this Calendar. For example, the actual maximum value of the MONTH field is 12 in some years, and 13 in other years in the Hebrew calendar system.

      The default implementation of this method uses an iterative algorithm to determine the actual maximum value for the calendar field. Subclasses should, if possible, override this with a more efficient implementation.

      Parameters:
      field - the calendar field
      Returns:
      the maximum of the given calendar field for the time value of this Calendar
      Since:
      1.2
      See Also:
      getMinimum(int), getMaximum(int), getGreatestMinimum(int), getLeastMaximum(int), getActualMinimum(int)

    • clone

      public Object clone()
      Creates and returns a copy of this object.
      Overrides:
      clone in class Object
      Returns:
      a copy of this object.
      See Also:
      Cloneable

    • toString

      public String toString()
      Return 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.
      Overrides:
      toString in class Object
      Returns:
      a string representation of this calendar.

    • toInstant

      public final Instant toInstant()
      Converts this object to an Instant.

      The conversion creates an Instant that represents the same point on the time-line as this Calendar.

      Returns:
      the instant representing the same point on the time-line
      Since:
      1.8