public abstract class Calendar extends Object implements Serializable, Cloneable, Comparable<Calendar>
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.
Like other locale-sensitive classes, Calendar
provides a class
method, getInstance
, for getting a default instance of
this class for general use. Calendar
's getInstance
method
returns a calendar whose locale is based on system settings and whose time fields
have been initialized with the current date and time:
Calendar rightNow = Calendar.getInstance()
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, two 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), or
there may be inconsistent information (such as "Tuesday, July 15, 1996" --
July 15, 1996 is actually a Monday).
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.
For the time of day: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
HOUR_OF_DAY AM_PM + HOUR
Note: There are certain possible ambiguities in interpretation of certain singular times, which are resolved in the following ways:
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 fieldf
before the call isdelta
, modulo any overflow that has occurred in fieldf
. 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 thanDAY_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 thanHOUR
.
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.
Date
,
GregorianCalendar
,
TimeZone
,
Serialized FormModifier and Type | Field and Description |
---|---|
static int |
ALL_STYLES
Requests both
SHORT and LONG styles in the map returned by
getDisplayNames(int, int, java.util.Locale) . |
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. |
protected boolean |
areFieldsSet
True iff the values in
fields[] correspond to time . |
static int |
AUGUST
Value of the
MONTH field indicating the eighth month of
the year. |
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. |
static int |
DST_OFFSET
Field number for
get and set indicating the
daylight savings 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. |
static int |
FIELD_COUNT
This is the total number of fields in this calendar.
|
protected int[] |
fields
Contains broken-down field values for the current value of
time if
areFieldsSet is true, or stale data corresponding to some previous value otherwise. |
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
Whether the corresponding element in
field[] has been set. |
protected boolean |
isTimeSet
Whether
time corresponds to the values in fields[] . |
static int |
JANUARY
Value of the
MONTH field indicating the first month of the
year. |
static int |
JULY
Value of the
MONTH field indicating the seventh month of
the year. |
static int |
JUNE
Value of the
MONTH field indicating the sixth month of the
year. |
static int |
LONG
Requests long names (such as "January") from
getDisplayName(int, int, java.util.Locale) or getDisplayNames(int, int, java.util.Locale) . |
static int |
MARCH
Value of the
MONTH field indicating the third month of the
year. |
static int |
MAY
Value of the
MONTH field indicating the fifth month of the
year. |
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 |
NOVEMBER
Value of the
MONTH field indicating the eleventh month of
the year. |
static int |
OCTOBER
Value of the
MONTH field indicating the tenth month of the
year. |
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. |
static int |
SHORT
Requests short names (such as "Jan") from
getDisplayName(int, int, java.util.Locale) or getDisplayNames(int, int, java.util.Locale) . |
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
A time in milliseconds since January 1, 1970.
|
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. |
Modifier | Constructor and Description |
---|---|
protected |
Calendar()
Constructs a
Calendar instance using the default TimeZone and Locale . |
protected |
Calendar(TimeZone timezone,
Locale locale)
Constructs a
Calendar instance using the specified TimeZone and Locale . |
Modifier and Type | Method and Description |
---|---|
abstract void |
add(int field,
int value)
Adds the specified amount to a
Calendar field. |
boolean |
after(Object calendar)
Returns whether the
Date specified by this Calendar instance is after the Date
specified by the parameter. |
boolean |
before(Object calendar)
Returns whether the
Date specified by this Calendar instance is before the
Date specified by the parameter. |
void |
clear()
Clears all of the fields of this
Calendar . |
void |
clear(int field)
Clears the specified field to zero and sets the isSet flag to
false . |
Object |
clone()
Returns a new
Calendar with the same properties. |
int |
compareTo(Calendar anotherCalendar)
Compares the times of the two
Calendar , which represent the milliseconds
from the January 1, 1970 00:00:00.000 GMT (Gregorian). |
protected void |
complete()
Computes the time from the fields if the time has not already been set.
|
protected abstract void |
computeFields()
Computes the
Calendar fields from time . |
protected abstract void |
computeTime()
Computes
time from the Calendar fields. |
boolean |
equals(Object object)
Compares the specified object to this
Calendar and returns whether they are
equal. |
int |
get(int field)
Gets the value of the specified field after computing the field values by
calling
complete() first. |
int |
getActualMaximum(int field)
Returns the maximum value of the specified field for the current date.
|
int |
getActualMinimum(int field)
Gets the minimum value of the specified field for the current date.
|
static Locale[] |
getAvailableLocales()
Returns an array of locales for which custom
Calendar instances
are available. |
String |
getDisplayName(int field,
int style,
Locale locale)
Returns a human-readable string for the value of
field
using the given style and locale. |
Map<String,Integer> |
getDisplayNames(int field,
int style,
Locale locale)
Returns a map of human-readable strings to corresponding values,
for the given field, style, and locale.
|
int |
getFirstDayOfWeek()
Gets the first day of the week for this
Calendar . |
abstract int |
getGreatestMinimum(int field)
Gets the greatest minimum value of the specified field.
|
static Calendar |
getInstance()
Constructs a new instance of the
Calendar subclass appropriate for the
default Locale . |
static Calendar |
getInstance(Locale locale)
Constructs a new instance of the
Calendar subclass appropriate for the
specified Locale . |
static Calendar |
getInstance(TimeZone timezone)
Constructs a new instance of the
Calendar subclass appropriate for the
default Locale , using the specified TimeZone . |
static Calendar |
getInstance(TimeZone timezone,
Locale locale)
Constructs a new instance of the
Calendar subclass appropriate for the
specified Locale . |
abstract int |
getLeastMaximum(int field)
Gets the smallest maximum value of the specified field.
|
abstract int |
getMaximum(int field)
Gets the greatest maximum value of the specified field.
|
int |
getMinimalDaysInFirstWeek()
Gets the minimal days in the first week of the year.
|
abstract int |
getMinimum(int field)
Gets the smallest minimum value of the specified field.
|
Date |
getTime()
Gets the time of this
Calendar as a Date object. |
long |
getTimeInMillis()
Computes the time from the fields if required and returns the time.
|
TimeZone |
getTimeZone()
Gets the timezone of this
Calendar . |
int |
hashCode()
Returns an integer hash code for the receiver.
|
protected int |
internalGet(int field)
Gets the value of the specified field without recomputing.
|
boolean |
isLenient()
Returns if this
Calendar accepts field values which are outside the valid
range for the field. |
boolean |
isSet(int field)
Returns whether the specified field is set.
|
abstract void |
roll(int field,
boolean increment)
Increment or decrement the specified field and wrap the value of the
field when it goes beyond the maximum or minimum value for the current
date.
|
void |
roll(int field,
int value)
Adds the specified amount to the specified field and wraps the value of
the field when it goes beyond the maximum or minimum value for the
current date.
|
void |
set(int field,
int value)
Sets a field to the specified value.
|
void |
set(int year,
int month,
int day)
Sets the year, month and day of the month fields.
|
void |
set(int year,
int month,
int day,
int hourOfDay,
int minute)
Sets the year, month, day of the month, hour of day and minute fields.
|
void |
set(int year,
int month,
int day,
int hourOfDay,
int minute,
int second)
Sets the year, month, day of the month, hour of day, minute and second
fields.
|
void |
setFirstDayOfWeek(int value)
Sets the first day of the week for this
Calendar . |
void |
setLenient(boolean value)
Sets this
Calendar to accept field values which are outside the valid
range for the field. |
void |
setMinimalDaysInFirstWeek(int value)
Sets the minimal days in the first week of the year.
|
void |
setTime(Date date)
Sets the time of this
Calendar . |
void |
setTimeInMillis(long milliseconds)
Sets the time of this
Calendar . |
void |
setTimeZone(TimeZone timezone)
Sets the
TimeZone used by this Calendar. |
String |
toString()
Returns the string representation of this
Calendar . |
protected boolean areFieldsSet
fields[]
correspond to time
. Despite the name, this
is effectively "are the values in fields[] up-to-date?" --- fields[]
may contain
non-zero values and isSet[]
may contain true
values even when
areFieldsSet
is false.
Accessing the fields via get
will ensure the fields are up-to-date.protected int[] fields
time
if
areFieldsSet
is true, or stale data corresponding to some previous value otherwise.
Accessing the fields via get
will ensure the fields are up-to-date.
The array length is always FIELD_COUNT
.protected boolean[] isSet
field[]
has been set. Initially, these are all
false. The first time the fields are computed, these are set to true and remain set even if
the data becomes stale: you must check areFieldsSet
if you want to know
whether the value is up-to-date.
Note that isSet
is not a safe alternative to accessing this array directly,
and will likewise return stale data!
The array length is always FIELD_COUNT
.protected boolean isTimeSet
time
corresponds to the values in fields[]
. If false, time
is out-of-date with respect to changes fields[]
.
Accessing the time via getTimeInMillis
will always return the correct value.protected long time
isTimeSet
.
Accessing the time via getTimeInMillis
will always return the correct value.public static final int JANUARY
MONTH
field indicating the first month of the
year.public static final int FEBRUARY
MONTH
field indicating the second month of
the year.public static final int MARCH
MONTH
field indicating the third month of the
year.public static final int APRIL
MONTH
field indicating the fourth month of
the year.public static final int MAY
MONTH
field indicating the fifth month of the
year.public static final int JUNE
MONTH
field indicating the sixth month of the
year.public static final int JULY
MONTH
field indicating the seventh month of
the year.public static final int AUGUST
MONTH
field indicating the eighth month of
the year.public static final int SEPTEMBER
MONTH
field indicating the ninth month of the
year.public static final int OCTOBER
MONTH
field indicating the tenth month of the
year.public static final int NOVEMBER
MONTH
field indicating the eleventh month of
the year.public static final int DECEMBER
MONTH
field indicating the twelfth month of
the year.public static final int UNDECIMBER
MONTH
field indicating the thirteenth month
of the year. Although GregorianCalendar
does not use this
value, lunar calendars do.public static final int SUNDAY
DAY_OF_WEEK
field indicating Sunday.public static final int MONDAY
DAY_OF_WEEK
field indicating Monday.public static final int TUESDAY
DAY_OF_WEEK
field indicating Tuesday.public static final int WEDNESDAY
DAY_OF_WEEK
field indicating Wednesday.public static final int THURSDAY
DAY_OF_WEEK
field indicating Thursday.public static final int FRIDAY
DAY_OF_WEEK
field indicating Friday.public static final int SATURDAY
DAY_OF_WEEK
field indicating Saturday.public static final int ERA
get
and set
indicating the
era, e.g., AD or BC in the Julian calendar. This is a calendar-specific
value; see subclass documentation.public static final int YEAR
get
and set
indicating the
year. This is a calendar-specific value; see subclass documentation.public static final int MONTH
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.public static final int WEEK_OF_YEAR
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.public static final int WEEK_OF_MONTH
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.public static final int DATE
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.DAY_OF_MONTH
,
Constant Field Valuespublic static final int DAY_OF_MONTH
get
and set
indicating the
day of the month. This is a synonym for DATE
. The first
day of the month has value 1.DATE
,
Constant Field Valuespublic static final int DAY_OF_YEAR
get
and set
indicating the
day number within the current year. The first day of the year has value
1.public static final int DAY_OF_WEEK
get
and set
indicating the
day of the week. This field takes values SUNDAY
,
MONDAY
, TUESDAY
, WEDNESDAY
,
THURSDAY
, FRIDAY
, and
SATURDAY
.public static final int DAY_OF_WEEK_IN_MONTH
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
.DAY_OF_WEEK
,
WEEK_OF_MONTH
,
Constant Field Valuespublic static final int AM_PM
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
.AM
,
PM
,
HOUR
,
Constant Field Valuespublic static final int HOUR
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.AM_PM
,
HOUR_OF_DAY
,
Constant Field Valuespublic static final int HOUR_OF_DAY
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.HOUR
,
Constant Field Valuespublic static final int MINUTE
get
and set
indicating the
minute within the hour. E.g., at 10:04:15.250 PM the MINUTE
is 4.public static final int SECOND
get
and set
indicating the
second within the minute. E.g., at 10:04:15.250 PM the
SECOND
is 15.public static final int MILLISECOND
get
and set
indicating the
millisecond within the second. E.g., at 10:04:15.250 PM the
MILLISECOND
is 250.public static final int ZONE_OFFSET
get
and set
indicating the
raw offset from GMT in milliseconds.public static final int DST_OFFSET
get
and set
indicating the
daylight savings offset in milliseconds.public static final int FIELD_COUNT
public static final int AM
AM_PM
field indicating the period of the day
from midnight to just before noon.public static final int PM
AM_PM
field indicating the period of the day
from noon to just before midnight.public static final int ALL_STYLES
SHORT
and LONG
styles in the map returned by
getDisplayNames(int, int, java.util.Locale)
.public static final int SHORT
getDisplayName(int, int, java.util.Locale)
or getDisplayNames(int, int, java.util.Locale)
.public static final int LONG
getDisplayName(int, int, java.util.Locale)
or getDisplayNames(int, int, java.util.Locale)
.protected Calendar()
Calendar
instance using the default TimeZone
and Locale
.public abstract void add(int field, int value)
Calendar
field.field
- the Calendar
field to modify.value
- the amount to add to the field.IllegalArgumentException
- if field
is DST_OFFSET
or ZONE_OFFSET
.public boolean after(Object calendar)
Date
specified by this Calendar
instance is after the Date
specified by the parameter. The comparison is not dependent on the time
zones of the Calendar
.calendar
- the Calendar
instance to compare.true
when this Calendar is after calendar, false
otherwise.IllegalArgumentException
- if the time is not set and the time cannot be computed
from the current field values.public boolean before(Object calendar)
Date
specified by this Calendar
instance is before the
Date
specified by the parameter. The comparison is not dependent on the
time zones of the Calendar
.calendar
- the Calendar
instance to compare.true
when this Calendar is before calendar, false
otherwise.IllegalArgumentException
- if the time is not set and the time cannot be computed
from the current field values.public final void clear()
Calendar
. All fields are initialized to
zero.public final void clear(int field)
false
.field
- the field to clear.public Object clone()
Calendar
with the same properties.protected void complete()
IllegalArgumentException
- if the time is not set and the time cannot be computed
from the current field values.protected abstract void computeFields()
Calendar
fields from time
.protected abstract void computeTime()
time
from the Calendar fields.IllegalArgumentException
- if the time cannot be computed from the current field
values.public boolean equals(Object object)
Calendar
and returns whether they are
equal. The object must be an instance of Calendar
and have the same
properties.equals
in class Object
object
- the object to compare with this object.true
if the specified object is equal to this Calendar
, false
otherwise.Object.hashCode()
public int get(int field)
complete()
first.field
- the field to get.IllegalArgumentException
- if the fields are not set, the time is not set, and the
time cannot be computed from the current field values.ArrayIndexOutOfBoundsException
- if the field is not inside the range of possible fields.
The range is starting at 0 up to FIELD_COUNT
.public int getActualMaximum(int field)
public int getActualMinimum(int field)
field
- the field.public static Locale[] getAvailableLocales()
Calendar
instances
are available.
Note that Android does not support user-supplied locale service providers.
public int getFirstDayOfWeek()
Calendar
.public abstract int getGreatestMinimum(int field)
getActualMinimum
can return for any possible
time.field
- the field.public static Calendar getInstance()
Calendar
subclass appropriate for the
default Locale
.Calendar
subclass instance set to the current date and time in
the default Timezone
.public static Calendar getInstance(Locale locale)
Calendar
subclass appropriate for the
specified Locale
.locale
- the locale to use.Calendar
subclass instance set to the current date and time.public static Calendar getInstance(TimeZone timezone)
Calendar
subclass appropriate for the
default Locale
, using the specified TimeZone
.timezone
- the TimeZone
to use.Calendar
subclass instance set to the current date and time in
the specified timezone.public static Calendar getInstance(TimeZone timezone, Locale locale)
Calendar
subclass appropriate for the
specified Locale
.timezone
- the TimeZone
to use.locale
- the Locale
to use.Calendar
subclass instance set to the current date and time in
the specified timezone.public abstract int getLeastMaximum(int field)
getActualMaximum()
can return for any
possible time.field
- the field number.public abstract int getMaximum(int field)
get
can return for the specified field.field
- the field.public int getMinimalDaysInFirstWeek()
public abstract int getMinimum(int field)
get
can return for the specified field.field
- the field number.public final Date getTime()
Calendar
as a Date
object.Date
initialized to the time of this Calendar
.IllegalArgumentException
- if the time is not set and the time cannot be computed
from the current field values.public long getTimeInMillis()
Calendar
.IllegalArgumentException
- if the time is not set and the time cannot be computed
from the current field values.public TimeZone getTimeZone()
Calendar
.TimeZone
used by this Calendar
.public int hashCode()
hashCode
in class Object
equals(java.lang.Object)
protected final int internalGet(int field)
field
- the field.public boolean isLenient()
Calendar
accepts field values which are outside the valid
range for the field.true
if this Calendar
is lenient, false
otherwise.public final boolean isSet(int field)
areFieldsSet
, making this method somewhat useless unless you're a subclass,
in which case you can access the isSet
array directly.
A field remains "set" from the first time its value is computed until it's cleared by one
of the clear
methods. Thus "set" does not mean "valid". You probably want to call
get
-- which will update fields as necessary -- rather than try to make use of
this method.
field
- a Calendar
field number.true
if the specified field is set, false
otherwise.public void roll(int field, int value)
field
- the field to roll.value
- the amount to add.public abstract void roll(int field, boolean increment)
field
- the number indicating the field to roll.increment
- true
to increment the field, false
to decrement.public void set(int field, int value)
field
- the code indicating the Calendar
field to modify.value
- the value.public final void set(int year, int month, int day)
year
- the year.month
- the month.day
- the day of the month.public final void set(int year, int month, int day, int hourOfDay, int minute)
year
- the year.month
- the month.day
- the day of the month.hourOfDay
- the hour of day.minute
- the minute.public final void set(int year, int month, int day, int hourOfDay, int minute, int second)
year
- the year.month
- the month.day
- the day of the month.hourOfDay
- the hour of day.minute
- the minute.second
- the second.public void setFirstDayOfWeek(int value)
Calendar
.value
- a Calendar
day of the week.public void setLenient(boolean value)
Calendar
to accept field values which are outside the valid
range for the field.value
- a boolean value.public void setMinimalDaysInFirstWeek(int value)
value
- the minimal days in the first week of the year.public final void setTime(Date date)
Calendar
.date
- a Date
object.public void setTimeInMillis(long milliseconds)
Calendar
.milliseconds
- the time as the number of milliseconds since Jan. 1, 1970.public void setTimeZone(TimeZone timezone)
TimeZone
used by this Calendar.timezone
- a TimeZone
.public String toString()
Calendar
.public int compareTo(Calendar anotherCalendar)
Calendar
, which represent the milliseconds
from the January 1, 1970 00:00:00.000 GMT (Gregorian).compareTo
in interface Comparable<Calendar>
anotherCalendar
- another calendar that this one is compared with.Calendar
s are equal, -1 if the time of
this Calendar
is before the other one, 1 if the time of this
Calendar
is after the other one.NullPointerException
- if the argument is null.IllegalArgumentException
- if the argument does not include a valid time
value.public String getDisplayName(int field, int style, Locale locale)
field
using the given style and locale. If no string is available, returns null.
The value is retrieved by invoking get(field)
.
For example, getDisplayName(MONTH, SHORT, Locale.US)
will return "Jan"
while getDisplayName(MONTH, LONG, Locale.US)
will return "January".
field
- the fieldstyle
- SHORT
or LONG
locale
- the localeNullPointerException
- if locale == null
IllegalArgumentException
- if field
or style
is invalidpublic Map<String,Integer> getDisplayNames(int field, int style, Locale locale)
For example, getDisplayNames(MONTH, ALL_STYLES, Locale.US)
would
contain mappings from "Jan" and "January" to JANUARY
, and so on.
field
- the fieldstyle
- SHORT
, LONG
, or ALL_STYLES
locale
- the localeNullPointerException
- if locale == null
IllegalArgumentException
- if field
or style
is invalid