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Calendar.javaAPI DocJava SE 6 API98112Tue Jun 10 00:25:52 BST 2008java.util

Calendar

public abstract class Calendar extends Object implements Serializable, Comparable, Cloneable
The Calendar class is an abstract class that provides methods for converting between a specific instant in time and a set of {@link #fields 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 when a Calendar is constructed. 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 {@link 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 {@link java.util.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.

see
java.lang.System#currentTimeMillis()
see
Date
see
GregorianCalendar
see
TimeZone
see
java.text.DateFormat
version
1.88, 11/17/05
author
Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu
since
JDK1.1

Fields Summary
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.
public static final int
YEAR
Field number for get and set indicating the year. This is a calendar-specific value; see subclass documentation.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

public static final int
DST_OFFSET
Field number for get and set indicating the daylight savings 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.

public static final int
FIELD_COUNT
The number of distinct fields recognized by get and set. Field numbers range from 0..FIELD_COUNT-1.
public static final int
SUNDAY
Value of the {@link #DAY_OF_WEEK} field indicating Sunday.
public static final int
MONDAY
Value of the {@link #DAY_OF_WEEK} field indicating Monday.
public static final int
TUESDAY
Value of the {@link #DAY_OF_WEEK} field indicating Tuesday.
public static final int
WEDNESDAY
Value of the {@link #DAY_OF_WEEK} field indicating Wednesday.
public static final int
THURSDAY
Value of the {@link #DAY_OF_WEEK} field indicating Thursday.
public static final int
FRIDAY
Value of the {@link #DAY_OF_WEEK} field indicating Friday.
public static final int
SATURDAY
Value of the {@link #DAY_OF_WEEK} field indicating Saturday.
public static final int
JANUARY
Value of the {@link #MONTH} field indicating the first month of the year in the Gregorian and Julian calendars.
public static final int
FEBRUARY
Value of the {@link #MONTH} field indicating the second month of the year in the Gregorian and Julian calendars.
public static final int
MARCH
Value of the {@link #MONTH} field indicating the third month of the year in the Gregorian and Julian calendars.
public static final int
APRIL
Value of the {@link #MONTH} field indicating the fourth month of the year in the Gregorian and Julian calendars.
public static final int
MAY
Value of the {@link #MONTH} field indicating the fifth month of the year in the Gregorian and Julian calendars.
public static final int
JUNE
Value of the {@link #MONTH} field indicating the sixth month of the year in the Gregorian and Julian calendars.
public static final int
JULY
Value of the {@link #MONTH} field indicating the seventh month of the year in the Gregorian and Julian calendars.
public static final int
AUGUST
Value of the {@link #MONTH} field indicating the eighth month of the year in the Gregorian and Julian calendars.
public static final int
SEPTEMBER
Value of the {@link #MONTH} field indicating the ninth month of the year in the Gregorian and Julian calendars.
public static final int
OCTOBER
Value of the {@link #MONTH} field indicating the tenth month of the year in the Gregorian and Julian calendars.
public static final int
NOVEMBER
Value of the {@link #MONTH} field indicating the eleventh month of the year in the Gregorian and Julian calendars.
public static final int
DECEMBER
Value of the {@link #MONTH} field indicating the twelfth month of the year in the Gregorian and Julian calendars.
public static final int
UNDECIMBER
Value of the {@link #MONTH} field indicating the thirteenth month of the year. Although GregorianCalendar does not use this value, lunar calendars do.
public static final int
AM
Value of the {@link #AM_PM} field indicating the period of the day from midnight to just before noon.
public static final int
PM
Value of the {@link #AM_PM} field indicating the period of the day from noon to just before midnight.
public static final int
ALL_STYLES
A style specifier for {@link #getDisplayNames(int, int, Locale) getDisplayNames} indicating names in all styles, such as "January" and "Jan".
public static final int
SHORT
A style specifier for {@link #getDisplayName(int, int, Locale) getDisplayName} and {@link #getDisplayNames(int, int, Locale) getDisplayNames} indicating a short name, such as "Jan".
public static final int
LONG
A style specifier for {@link #getDisplayName(int, int, Locale) getDisplayName} and {@link #getDisplayNames(int, int, Locale) getDisplayNames} indicating a long name, such as "January".
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.
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.
private transient int[]
stamp
Pseudo-time-stamps which specify when each field was set. There are two special values, UNSET and COMPUTED. Values from MINIMUM_USER_SET to Integer.MAX_VALUE are legal user set values.
protected long
time
The currently set time for this calendar, expressed in milliseconds after January 1, 1970, 0:00:00 GMT.
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[].
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.
transient boolean
areAllFieldsSet
True if all fields have been set.
private boolean
lenient
True if this calendar allows out-of-range field values during computation of time from fields[].
private TimeZone
zone
The TimeZone used by this calendar. Calendar uses the time zone data to translate between locale and GMT time.
private transient boolean
sharedZone
True if zone references to a shared TimeZone object.
private int
firstDayOfWeek
The first day of the week, with possible values SUNDAY, MONDAY, etc. This is a locale-dependent value.
private int
minimalDaysInFirstWeek
The number of days required for the first week in a month or year, with possible values from 1 to 7. This is a locale-dependent value.
private static Hashtable
cachedLocaleData
Cache to hold the firstDayOfWeek and minimalDaysInFirstWeek of a Locale.
private static final int
UNSET
The corresponding fields[] has no value.
private static final int
COMPUTED
The value of the corresponding fields[] has been calculated internally.
private static final int
MINIMUM_USER_STAMP
The value of the corresponding fields[] has been set externally. Stamp values which are greater than 1 represents the (pseudo) time when the corresponding fields[] value was set.
static final int
ALL_FIELDS
The mask value that represents all of the fields.
private int
nextStamp
The next available value for stamp[], an internal array. This actually should not be written out to the stream, and will probably be removed from the stream in the near future. In the meantime, a value of MINIMUM_USER_STAMP should be used.
static final int
currentSerialVersion
private int
serialVersionOnStream
The version of the serialized data on the stream. Possible values:
0 or not present on stream
JDK 1.1.5 or earlier.
1
JDK 1.1.6 or later. Writes a correct 'time' value as well as compatible values for other fields. This is a transitional format.
When streaming out this class, the most recent format and the highest allowable serialVersionOnStream is written.
static final long
serialVersionUID
static final int
ERA_MASK
static final int
YEAR_MASK
static final int
MONTH_MASK
static final int
WEEK_OF_YEAR_MASK
static final int
WEEK_OF_MONTH_MASK
static final int
DAY_OF_MONTH_MASK
static final int
DATE_MASK
static final int
DAY_OF_YEAR_MASK
static final int
DAY_OF_WEEK_MASK
static final int
DAY_OF_WEEK_IN_MONTH_MASK
static final int
AM_PM_MASK
static final int
HOUR_MASK
static final int
HOUR_OF_DAY_MASK
static final int
MINUTE_MASK
static final int
SECOND_MASK
static final int
MILLISECOND_MASK
static final int
ZONE_OFFSET_MASK
static final int
DST_OFFSET_MASK
private static final String[]
FIELD_NAME
Constructors Summary
protected Calendar()
Constructs a Calendar with the default time zone and locale.

see
TimeZone#getDefault


                         
     
    
        this(TimeZone.getDefaultRef(), Locale.getDefault());
	sharedZone = true;
protected Calendar(TimeZone zone, Locale aLocale)
Constructs a calendar with the specified time zone and locale.

param
zone the time zone to use
param
aLocale the locale for the week data

        fields = new int[FIELD_COUNT];
        isSet = new boolean[FIELD_COUNT];
        stamp = new int[FIELD_COUNT];

        this.zone = zone;
        setWeekCountData(aLocale);
Methods Summary
public abstract voidadd(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).

param
field the calendar field.
param
amount the amount of date or time to be added to the field.
see
#roll(int,int)
see
#set(int,int)

private final voidadjustStamp()
Adjusts the stamp[] values before nextStamp overflow. nextStamp
is set to the next stamp value upon the return.
	int max = MINIMUM_USER_STAMP;
	int newStamp = MINIMUM_USER_STAMP;

	for (;;) {
	    int min = Integer.MAX_VALUE;
	    for (int i = 0; i < stamp.length; i++) {
		int v = stamp[i];
		if (v >= newStamp && min > v) {
		    min = v;
		}
		if (max < v) {
		    max = v;
		}
	    }
	    if (max != min && min == Integer.MAX_VALUE) {
		break;
	    }
	    for (int i = 0; i < stamp.length; i++) {
		if (stamp[i] == min) {
		    stamp[i] = newStamp;
		}
	    }
	    newStamp++;
	    if (min == max) {
		break;
	    }
	}
	nextStamp = newStamp;
    
public booleanafter(java.lang.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.
param
when the Object to be compared
return
true if the time of this Calendar is
after the time represented by when; false
otherwise.
see
#compareTo(Calendar)
	return when instanceof Calendar
	    && compareTo((Calendar)when) > 0;
    
private static final intaggregateStamp(int stamp_a, int stamp_b)
Returns the pseudo-time-stamp for two fields, given their
individual pseudo-time-stamps. If either of the fields
is unset, then the aggregate is unset. Otherwise, the
aggregate is the later of the two stamps.
	if (stamp_a == UNSET || stamp_b == UNSET) {
	    return UNSET;
	}
        return (stamp_a > stamp_b) ? stamp_a : stamp_b;
    
private static final voidappendValue(java.lang.StringBuilder sb, java.lang.String item, boolean valid, long value)
	sb.append(item).append('=");
	if (valid) {
	    sb.append(value);
	} else {
	    sb.append('?");
	}
    
public booleanbefore(java.lang.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.
param
when the Object to be compared
return
true if the time of this
Calendar is before the time represented by
when; false otherwise.
see
#compareTo(Calendar)
	return when instanceof Calendar
	    && compareTo((Calendar)when) < 0;
    
booleancheckDisplayNameParams(int field, int style, int minStyle, int maxStyle, java.util.Locale locale, int fieldMask)
	if (field < 0 || field >= fields.length ||
	    style < minStyle || style > maxStyle) {
	    throw new IllegalArgumentException();
	}
	if (locale == null) {
	    throw new NullPointerException();
	}
	return isFieldSet(fieldMask, field);
    
public final voidclear()
Sets all the calendar field values and the time value
(millisecond offset from the Epoch) of
this Calendar undefined. This means that {@link
#isSet(int) 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
#clear(int)
	for (int i = 0; i < fields.length; ) {
	    stamp[i] = fields[i] = 0; // UNSET == 0
	    isSet[i++] = false;
	}
        areAllFieldsSet = areFieldsSet = false;
        isTimeSet = false;
    
public final voidclear(int field)
Sets the given calendar field value and the time value
(millisecond offset from the Epoch) of
this Calendar undefined. This means that {@link
#isSet(int) 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 {@link #HOUR_OF_DAY}, {@link #HOUR} and {@link #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 {@link
#set(int,int) set(Calendar.HOUR_OF_DAY, 0)} to reset the hour
value.
param
field the calendar field to be cleared.
see
#clear()
	fields[field] = 0;
	stamp[field] = UNSET;
	isSet[field] = false;

	areAllFieldsSet = areFieldsSet = false;
	isTimeSet = false;
    
public java.lang.Objectclone()
Creates and returns a copy of this object.
return
a copy of this object.
        try {
            Calendar other = (Calendar) super.clone();

            other.fields = new int[FIELD_COUNT];
            other.isSet = new boolean[FIELD_COUNT];
            other.stamp = new int[FIELD_COUNT];
	    for (int i = 0; i < FIELD_COUNT; i++) {
		other.fields[i] = fields[i];
		other.stamp[i] = stamp[i];
		other.isSet[i] = isSet[i];
	    }
            other.zone = (TimeZone) zone.clone();
            return other;
        }
        catch (CloneNotSupportedException e) {
            // this shouldn't happen, since we are Cloneable
            throw new InternalError();
        }
    
public intcompareTo(java.util.Calendar anotherCalendar)
Compares the time values (millisecond offsets from the Epoch) represented by two
Calendar objects.
param
anotherCalendar the Calendar to be compared.
return
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.
exception
NullPointerException if the specified Calendar is
null.
exception
IllegalArgumentException if the time value of the
specified Calendar object can't be obtained due to
any invalid calendar values.
since
1.5
	return compareTo(getMillisOf(anotherCalendar));
    
private intcompareTo(long t)
	long thisTime = getMillisOf(this);
	return (thisTime > t) ? 1 : (thisTime == t) ? 0 : -1;
    
protected voidcomplete()
Fills in any unset fields in the calendar fields. First, the {@link
#computeTime()} method is called if the time value (millisecond offset
from the Epoch) has not been calculated from
calendar field values. Then, the {@link #computeFields()} method is
called to calculate all calendar field values.
        if (!isTimeSet)
	    updateTime();
        if (!areFieldsSet || !areAllFieldsSet) {
            computeFields(); // fills in unset fields
            areAllFieldsSet = areFieldsSet = true;
        }
    
protected abstract voidcomputeFields()
Converts the current millisecond time value {@link #time}
to calendar field values in {@link #fields 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
{@link #complete()} method.
see
#computeTime()
protected abstract voidcomputeTime()
Converts the current calendar field values in {@link #fields fields[]}
to the millisecond time value
{@link #time}.
see
#complete()
see
#computeFields()
private static java.util.CalendarcreateCalendar(java.util.TimeZone zone, java.util.Locale aLocale)
	// If the specified locale is a Thai locale, returns a BuddhistCalendar
	// instance.
	if ("th".equals(aLocale.getLanguage())
	    && ("TH".equals(aLocale.getCountry()))) {
	    return new sun.util.BuddhistCalendar(zone, aLocale);
	} else if ("JP".equals(aLocale.getVariant())
		   && "JP".equals(aLocale.getCountry())
		   && "ja".equals(aLocale.getLanguage())) {
	    return new JapaneseImperialCalendar(zone, aLocale);
	}	    

	// else create the default calendar
        return new GregorianCalendar(zone, aLocale);	
    
public booleanequals(java.lang.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 {@link #compareTo(Calendar) compareTo} method to
compare only the time values.
param
obj the object to compare with.
return
true if this object is equal to obj;
false otherwise.
        if (this == obj)
            return true;
	try {
	    Calendar that = (Calendar)obj;
	    return compareTo(getMillisOf(that)) == 0 &&
		lenient == that.lenient &&
		firstDayOfWeek == that.firstDayOfWeek &&
		minimalDaysInFirstWeek == that.minimalDaysInFirstWeek &&
		zone.equals(that.zone);
	} catch (Exception e) {
	    // Note: GregorianCalendar.computeTime throws
	    // IllegalArgumentException if the ERA value is invalid
	    // even it's in lenient mode.
	}
	return false;
    
public intget(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
{@link #complete()} method, which process is calendar
system dependent.
param
field the given calendar field.
return
the value for the given calendar field.
throws
ArrayIndexOutOfBoundsException if the specified field is out of range
(field < 0 || field >= FIELD_COUNT).
see
#set(int,int)
see
#complete()
        complete();
	return internalGet(field);
    
public intgetActualMaximum(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.
param
field the calendar field
return
the maximum of the given calendar field for the time
value of this Calendar
see
#getMinimum(int)
see
#getMaximum(int)
see
#getGreatestMinimum(int)
see
#getLeastMaximum(int)
see
#getActualMinimum(int)
since
1.2
        int fieldValue = getLeastMaximum(field);
        int endValue = getMaximum(field);

        // if we know that the maximum value is always the same, just return it.
        if (fieldValue == endValue) {
            return fieldValue;
        }

        // clone the calendar so we don't mess with the real one, and set it to
        // accept anything for the field values.
        Calendar work = (Calendar)this.clone();
        work.setLenient(true);

        // if we're counting weeks, set the day of the week to Sunday.  We know the
        // last week of a month or year will contain the first day of the week.
        if (field == WEEK_OF_YEAR || field == WEEK_OF_MONTH)
            work.set(DAY_OF_WEEK, firstDayOfWeek);

        // now try each value from getLeastMaximum() to getMaximum() one by one until
        // we get a value that normalizes to another value.  The last value that
        // normalizes to itself is the actual maximum for the current date
        int result = fieldValue;

        do {
            work.set(field, fieldValue);
            if (work.get(field) != fieldValue) {
                break;
            } else {
                result = fieldValue;
                fieldValue++;
            }
        } while (fieldValue <= endValue);

        return result;
    
public intgetActualMinimum(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().
param
field the calendar field
return
the minimum of the given calendar field for the time
value of this Calendar
see
#getMinimum(int)
see
#getMaximum(int)
see
#getGreatestMinimum(int)
see
#getLeastMaximum(int)
see
#getActualMaximum(int)
since
1.2
        int fieldValue = getGreatestMinimum(field);
        int endValue = getMinimum(field);

        // if we know that the minimum value is always the same, just return it
        if (fieldValue == endValue) {
            return fieldValue;
        }

        // clone the calendar so we don't mess with the real one, and set it to
        // accept anything for the field values
        Calendar work = (Calendar)this.clone();
        work.setLenient(true);

        // now try each value from getLeastMaximum() to getMaximum() one by one until
        // we get a value that normalizes to another value.  The last value that
        // normalizes to itself is the actual minimum for the current date
        int result = fieldValue;

        do {
            work.set(field, fieldValue);
            if (work.get(field) != fieldValue) {
                break;
            } else {
                result = fieldValue;
                fieldValue--;
            }
        } while (fieldValue >= endValue);

        return result;
    
public static synchronized java.util.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 {@link java.util.Locale#US Locale.US}.
return
An array of locales for which localized
Calendar instances are available.
        return DateFormat.getAvailableLocales();
    
public java.lang.StringgetDisplayName(int field, int style, java.util.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
{@link Calendar#get(int) 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 {@link #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 {@link #DAY_OF_MONTH} field, and this method
would return null.


The default implementation supports the calendar fields for
which a {@link DateFormatSymbols} has names in the given
locale.
param
field
the calendar field for which the string representation
is returned
param
style
the style applied to the string representation; one of
{@link #SHORT} or {@link #LONG}.
param
locale
the locale for the string representation
return
the string representation of the given
field in the given style, or
null if no string representation is
applicable.
exception
IllegalArgumentException
if field or style is invalid,
or if this Calendar is non-lenient and any
of the calendar fields have invalid values
exception
NullPointerException
if locale is null
since
1.6
	if (!checkDisplayNameParams(field, style, ALL_STYLES, LONG, locale,
				    ERA_MASK|MONTH_MASK|DAY_OF_WEEK_MASK|AM_PM_MASK)) {
	    return null;
	}

	DateFormatSymbols symbols = DateFormatSymbols.getInstance(locale);
	String[] strings = getFieldStrings(field, style, symbols);
	if (strings != null) {
	    int fieldValue = get(field);
	    if (fieldValue < strings.length) {
		return strings[fieldValue];
	    }
	}
	return null;
    
public java.util.MapgetDisplayNames(int field, int style, java.util.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 {@link
GregorianCalendar}, the returned map would contain "Jan" to
{@link #JANUARY}, "Feb" to {@link #FEBRUARY}, and so on, in the
{@linkplain #SHORT short} style in an English locale.


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 {@link #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 {@link DateFormatSymbols}. For example, if field
is {@link #MONTH} and style is {@link
#ALL_STYLES}, this method returns a Map containing
all strings returned by {@link DateFormatSymbols#getShortMonths()}
and {@link DateFormatSymbols#getMonths()}.
param
field
the calendar field for which the display names are returned
param
style
the style applied to the display names; one of {@link
#SHORT}, {@link #LONG}, or {@link #ALL_STYLES}.
param
locale
the locale for the display names
return
a Map containing all display names in
style and locale and their
field values, or null if no display names
are defined for field
exception
IllegalArgumentException
if field or style is invalid,
or if this Calendar is non-lenient and any
of the calendar fields have invalid values
exception
NullPointerException
if locale is null
since
1.6
	if (!checkDisplayNameParams(field, style, ALL_STYLES, LONG, locale,
				    ERA_MASK|MONTH_MASK|DAY_OF_WEEK_MASK|AM_PM_MASK)) {
	    return null;
	}

	// ALL_STYLES
	if (style == ALL_STYLES) {
	    Map<String,Integer> shortNames = getDisplayNamesImpl(field, SHORT, locale);
	    if (field == ERA || field == AM_PM) {
		return shortNames;
	    }
	    Map<String,Integer> longNames = getDisplayNamesImpl(field, LONG, locale);
	    if (shortNames == null) {
		return longNames;
	    }
	    if (longNames != null) {
		shortNames.putAll(longNames);
	    }
	    return shortNames;
	}

	// SHORT or LONG
	return getDisplayNamesImpl(field, style, locale);
    
private java.util.MapgetDisplayNamesImpl(int field, int style, java.util.Locale locale)
	DateFormatSymbols symbols = DateFormatSymbols.getInstance(locale);
	String[] strings = getFieldStrings(field, style, symbols);
	if (strings != null) {
	    Map<String,Integer> names = new HashMap<String,Integer>();
	    for (int i = 0; i < strings.length; i++) {
		if (strings[i].length() == 0) {
		    continue;
		}
		names.put(strings[i], i);
	    }
	    return names;
	}
	return null;
    
static final java.lang.StringgetFieldName(int field)
Returns the name of the specified calendar field.
param
field the calendar field
return
the calendar field name
exception
IndexOutOfBoundsException if field is negative,
equal to or greater then FIELD_COUNT.

                                       
         
	return FIELD_NAME[field];
    
private java.lang.String[]getFieldStrings(int field, int style, java.text.DateFormatSymbols symbols)
	String[] strings = null;
	switch (field) {
	case ERA:
	    strings = symbols.getEras();
	    break;

	case MONTH:
	    strings = (style == LONG) ? symbols.getMonths() : symbols.getShortMonths();
	    break;

	case DAY_OF_WEEK:
	    strings = (style == LONG) ? symbols.getWeekdays() : symbols.getShortWeekdays();
	    break;

	case AM_PM:
	    strings = symbols.getAmPmStrings();
	    break;
	}
	return strings;
    
public intgetFirstDayOfWeek()
Gets what the first day of the week is; e.g., SUNDAY in the U.S.,
MONDAY in France.
return
the first day of the week.
see
#setFirstDayOfWeek(int)
see
#getMinimalDaysInFirstWeek()
        return firstDayOfWeek;
    
public abstract intgetGreatestMinimum(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 {@link
#getActualMinimum(int)} for any possible time value. The
greatest minimum value depends on calendar system specific
parameters of the instance.
param
field the calendar field.
return
the highest minimum value for the given calendar field.
see
#getMinimum(int)
see
#getMaximum(int)
see
#getLeastMaximum(int)
see
#getActualMinimum(int)
see
#getActualMaximum(int)
public static java.util.CalendargetInstance()
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 locale.
return
a Calendar.
        Calendar cal = createCalendar(TimeZone.getDefaultRef(), Locale.getDefault());
	cal.sharedZone = true;
	return cal;
    
public static java.util.CalendargetInstance(java.util.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 locale.
param
zone the time zone to use
return
a Calendar.
        return createCalendar(zone, Locale.getDefault());
    
public static java.util.CalendargetInstance(java.util.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.
param
aLocale the locale for the week data
return
a Calendar.
        Calendar cal = createCalendar(TimeZone.getDefaultRef(), aLocale);
	cal.sharedZone = true;
	return cal;
    
public static java.util.CalendargetInstance(java.util.TimeZone zone, java.util.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.
param
zone the time zone to use
param
aLocale the locale for the week data
return
a Calendar.
	return createCalendar(zone, aLocale);
    
public abstract intgetLeastMaximum(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 {@link
#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.
param
field the calendar field.
return
the lowest maximum value for the given calendar field.
see
#getMinimum(int)
see
#getMaximum(int)
see
#getGreatestMinimum(int)
see
#getActualMinimum(int)
see
#getActualMaximum(int)
public abstract intgetMaximum(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 {@link #get(int) get} method
for any possible time value. The maximum value depends on
calendar system specific parameters of the instance.
param
field the calendar field.
return
the maximum value for the given calendar field.
see
#getMinimum(int)
see
#getGreatestMinimum(int)
see
#getLeastMaximum(int)
see
#getActualMinimum(int)
see
#getActualMaximum(int)
private static final longgetMillisOf(java.util.Calendar calendar)
	if (calendar.isTimeSet) {
	    return calendar.time;
	}
	Calendar cal = (Calendar) calendar.clone();
	cal.setLenient(true);
	return cal.getTimeInMillis();
    
public intgetMinimalDaysInFirstWeek()
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.
return
the minimal days required in the first week of the year.
see
#setMinimalDaysInFirstWeek(int)
        return minimalDaysInFirstWeek;
    
public abstract intgetMinimum(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 {@link #get(int) get} method
for any possible time value. The minimum value depends on
calendar system specific parameters of the instance.
param
field the calendar field.
return
the minimum value for the given calendar field.
see
#getMaximum(int)
see
#getGreatestMinimum(int)
see
#getLeastMaximum(int)
see
#getActualMinimum(int)
see
#getActualMaximum(int)
final intgetSetStateFields()
Returns a field mask (bit mask) indicating all calendar fields that
have the state of externally or internally set.
return
a bit mask indicating set state fields
	int mask = 0;
	for (int i = 0; i < fields.length; i++) {
	    if (stamp[i] != UNSET) {
		mask |= 1 << i;
	    }
	}
	return mask;
    
public final java.util.DategetTime()
Returns a Date object representing this
Calendar's time value (millisecond offset from the Epoch").
return
a Date representing the time value.
see
#setTime(Date)
see
#getTimeInMillis()
        return new Date(getTimeInMillis());
    
public longgetTimeInMillis()
Returns this Calendar's time value in milliseconds.
return
the current time as UTC milliseconds from the epoch.
see
#getTime()
see
#setTimeInMillis(long)
        if (!isTimeSet) {
	    updateTime();
	}
        return time;
    
public java.util.TimeZonegetTimeZone()
Gets the time zone.
return
the time zone object associated with this calendar.
	// If the TimeZone object is shared by other Calendar instances, then
	// create a clone.
	if (sharedZone) {
	    zone = (TimeZone) zone.clone();
	    sharedZone = false;
	}
        return zone;
    
java.util.TimeZonegetZone()
Returns the time zone (without cloning).
	return zone;
    
public inthashCode()
Returns a hash code for this calendar.
return
a hash code value for this object.
since
1.2
	// 'otheritems' represents the hash code for the previous versions.
	int otheritems = (lenient ? 1 : 0)
            | (firstDayOfWeek << 1)
            | (minimalDaysInFirstWeek << 4)
            | (zone.hashCode() << 7);
	long t = getMillisOf(this);
	return (int) t ^ (int)(t >> 32) ^ otheritems;
    
protected final intinternalGet(int field)
Returns the value of the given calendar field. This method does
not involve normalization or validation of the field value.
param
field the given calendar field.
return
the value for the given calendar field.
see
#get(int)
        return fields[field];
    
final voidinternalSet(int field, int value)
Sets the value of the given calendar field. This method does
not affect any setting state of the field in this
Calendar instance.
throws
IndexOutOfBoundsException if the specified field is out of range
(field < 0 || field >= FIELD_COUNT).
see
#areFieldsSet
see
#isTimeSet
see
#areAllFieldsSet
see
#set(int,int)
        fields[field] = value;
    
private voidinvalidateWeekFields()
Sets the WEEK_OF_MONTH and WEEK_OF_YEAR fields to new values with the
new parameter value if they have been calculated internally.
	if (stamp[WEEK_OF_MONTH] != COMPUTED &&
	    stamp[WEEK_OF_YEAR] != COMPUTED) {
	    return;
	}

	// We have to check the new values of these fields after changing
	// firstDayOfWeek and/or minimalDaysInFirstWeek. If the field values
	// have been changed, then set the new values. (4822110)
	Calendar cal = (Calendar) clone();
	cal.setLenient(true);
	cal.clear(WEEK_OF_MONTH);
	cal.clear(WEEK_OF_YEAR);

	if (stamp[WEEK_OF_MONTH] == COMPUTED) {
	    int weekOfMonth = cal.get(WEEK_OF_MONTH);
	    if (fields[WEEK_OF_MONTH] != weekOfMonth) {
		fields[WEEK_OF_MONTH] = weekOfMonth;
	    }
	}

	if (stamp[WEEK_OF_YEAR] == COMPUTED) {
	    int weekOfYear = cal.get(WEEK_OF_YEAR);
	    if (fields[WEEK_OF_YEAR] != weekOfYear) {
		fields[WEEK_OF_YEAR] = weekOfYear;
	    }
	}
    
final booleanisExternallySet(int field)
Returns whether the value of the specified calendar field has been set
externally by calling one of the setter methods rather than by the
internal time calculation.
return
true if the field has been set externally,
false otherwise.
exception
IndexOutOfBoundsException if the specified
field is out of range
(field < 0 || field >= FIELD_COUNT).
see
#selectFields()
see
#setFieldsComputed(int)
	return stamp[field] >= MINIMUM_USER_STAMP;
    
static final booleanisFieldSet(int fieldMask, int field)
Returns whether the specified field is on in the
fieldMask.
	return (fieldMask & (1 << field)) != 0;
    
final booleanisFullyNormalized()
Returns whether the calendar fields are fully in sync with the time
value.
	return areFieldsSet && areAllFieldsSet;
    
public booleanisLenient()
Tells whether date/time interpretation is to be lenient.
return
true if the interpretation mode of this calendar is lenient;
false otherwise.
see
#setLenient(boolean)
        return lenient;
    
final booleanisPartiallyNormalized()
Returns whether the calendar fields are partially in sync with the time
value or fully in sync but not stamp values are not normalized yet.
	return areFieldsSet && !areAllFieldsSet;
    
public final booleanisSet(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.
return
true if the given calendar field has a value set;
false otherwise.
        return stamp[field] != UNSET;
    
private voidreadObject(java.io.ObjectInputStream stream)
Reconstitutes this object from a stream (i.e., deserialize it).
	final ObjectInputStream input = stream;
        input.defaultReadObject();

        stamp = new int[FIELD_COUNT];

        // Starting with version 2 (not implemented yet), we expect that
        // fields[], isSet[], isTimeSet, and areFieldsSet may not be
        // streamed out anymore.  We expect 'time' to be correct.
        if (serialVersionOnStream >= 2)
        {
            isTimeSet = true;
            if (fields == null) fields = new int[FIELD_COUNT];
            if (isSet == null) isSet = new boolean[FIELD_COUNT];
        }
        else if (serialVersionOnStream >= 0)
        {
            for (int i=0; i<FIELD_COUNT; ++i)
                stamp[i] = isSet[i] ? COMPUTED : UNSET;
        }

        serialVersionOnStream = currentSerialVersion;

	// If there's a ZoneInfo object, use it for zone.
	try {
	    ZoneInfo zi = (ZoneInfo) AccessController.doPrivileged(
		new PrivilegedExceptionAction() {
		    public Object run() throws Exception {
			return input.readObject();
		    }
		});
	    if (zi != null) {
		zone = zi;
	    }
	} catch (Exception e) {
	}

	// If the deserialized object has a SimpleTimeZone, try to
	// replace it with a ZoneInfo equivalent (as of 1.4) in order
	// to be compatible with the SimpleTimeZone-based
	// implementation as much as possible.
	if (zone instanceof SimpleTimeZone) {
	    String id = zone.getID();
	    TimeZone zi = TimeZone.getTimeZone(id);
	    if (zi != null && zi.hasSameRules(zone) && zi.getID().equals(id)) {
		zone = zi;
	    }
	}
    
public abstract voidroll(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.
param
field the time field.
param
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
Calendar#add(int,int)
see
Calendar#set(int,int)
public voidroll(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 {@link #roll(int,boolean) 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.
param
field the calendar field.
param
amount the signed amount to add to the calendar field.
since
1.2
see
#roll(int,boolean)
see
#add(int,int)
see
#set(int,int)
        while (amount > 0) {
            roll(field, true);
            amount--;
        }
        while (amount < 0) {
            roll(field, false);
            amount++;
        }
    
final intselectFields()
Returns a field mask indicating which calendar field values
to be used to calculate the time value. The calendar fields are
returned as a bit mask, each bit of which corresponds to a field, i.e.,
the mask value of field is (1 <<
field). For example, 0x26 represents the YEAR,
MONTH, and DAY_OF_MONTH fields (i.e., 0x26 is
equal to
(1<<YEAR)|(1<<MONTH)|(1<<DAY_OF_MONTH)).


This method supports the calendar fields resolution as described in
the class description. If the bit mask for a given field is on and its
field has not been set (i.e., isSet(field) is
false), then the default value of the field has to be
used, which case means that the field has been selected because the
selected combination involves the field.
return
a bit mask of selected fields
see
#isExternallySet(int)
see
#setInternallySetState(int)
	// This implementation has been taken from the GregorianCalendar class.

	// The YEAR field must always be used regardless of its SET
	// state because YEAR is a mandatory field to determine the date
	// and the default value (EPOCH_YEAR) may change through the
	// normalization process.
	int fieldMask = YEAR_MASK;

	if (stamp[ERA] != UNSET) {
	    fieldMask |= ERA_MASK;
	}
        // Find the most recent group of fields specifying the day within
        // the year.  These may be any of the following combinations:
        //   MONTH + DAY_OF_MONTH
        //   MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
        //   MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
        //   DAY_OF_YEAR
        //   WEEK_OF_YEAR + DAY_OF_WEEK
        // We look for the most recent of the fields in each group to determine
        // the age of the group.  For groups involving a week-related field such
        // as WEEK_OF_MONTH, DAY_OF_WEEK_IN_MONTH, or WEEK_OF_YEAR, both the
        // week-related field and the DAY_OF_WEEK must be set for the group as a
        // whole to be considered.  (See bug 4153860 - liu 7/24/98.)
        int dowStamp = stamp[DAY_OF_WEEK];
        int monthStamp = stamp[MONTH];
        int domStamp = stamp[DAY_OF_MONTH];
        int womStamp = aggregateStamp(stamp[WEEK_OF_MONTH], dowStamp);
        int dowimStamp = aggregateStamp(stamp[DAY_OF_WEEK_IN_MONTH], dowStamp);
        int doyStamp = stamp[DAY_OF_YEAR];
        int woyStamp = aggregateStamp(stamp[WEEK_OF_YEAR], dowStamp);

        int bestStamp = domStamp;
        if (womStamp > bestStamp) {
	    bestStamp = womStamp;
	}
        if (dowimStamp > bestStamp) {
	    bestStamp = dowimStamp;
	}
        if (doyStamp > bestStamp) {
	    bestStamp = doyStamp;
	}
        if (woyStamp > bestStamp) {
	    bestStamp = woyStamp;
	}

        /* No complete combination exists.  Look for WEEK_OF_MONTH,
         * DAY_OF_WEEK_IN_MONTH, or WEEK_OF_YEAR alone.  Treat DAY_OF_WEEK alone
         * as DAY_OF_WEEK_IN_MONTH.
         */
        if (bestStamp == UNSET) {
            womStamp = stamp[WEEK_OF_MONTH];
            dowimStamp = Math.max(stamp[DAY_OF_WEEK_IN_MONTH], dowStamp);
            woyStamp = stamp[WEEK_OF_YEAR];
            bestStamp = Math.max(Math.max(womStamp, dowimStamp), woyStamp);

            /* Treat MONTH alone or no fields at all as DAY_OF_MONTH.  This may
             * result in bestStamp = domStamp = UNSET if no fields are set,
             * which indicates DAY_OF_MONTH.
             */
            if (bestStamp == UNSET) {
                bestStamp = domStamp = monthStamp;
            }
        }

        if (bestStamp == domStamp ||
           (bestStamp == womStamp && stamp[WEEK_OF_MONTH] >= stamp[WEEK_OF_YEAR]) ||
           (bestStamp == dowimStamp && stamp[DAY_OF_WEEK_IN_MONTH] >= stamp[WEEK_OF_YEAR])) {
	    fieldMask |= MONTH_MASK;
            if (bestStamp == domStamp) {
		fieldMask |= DAY_OF_MONTH_MASK;
            } else {
		assert (bestStamp == womStamp || bestStamp == dowimStamp);
                if (dowStamp != UNSET) {
		    fieldMask |= DAY_OF_WEEK_MASK;
                }
                if (bestStamp == womStamp) {
		    fieldMask |= WEEK_OF_MONTH_MASK;
                } else {
		    assert (bestStamp == dowimStamp);
		    if (stamp[DAY_OF_WEEK_IN_MONTH] != UNSET) {
			fieldMask |= DAY_OF_WEEK_IN_MONTH_MASK;
		    }
		}
	    }
        } else {
            assert (bestStamp == doyStamp || bestStamp == woyStamp ||
		    bestStamp == UNSET);
            if (bestStamp == doyStamp) {
		fieldMask |= DAY_OF_YEAR_MASK;
            } else {
		assert (bestStamp == woyStamp);
                if (dowStamp != UNSET) {
		    fieldMask |= DAY_OF_WEEK_MASK;
                }
		fieldMask |= WEEK_OF_YEAR_MASK;
	    }
	}

        // Find the best set of fields specifying the time of day.  There
        // are only two possibilities here; the HOUR_OF_DAY or the
        // AM_PM and the HOUR.
        int hourOfDayStamp = stamp[HOUR_OF_DAY];
        int hourStamp = aggregateStamp(stamp[HOUR], stamp[AM_PM]);
        bestStamp = (hourStamp > hourOfDayStamp) ? hourStamp : hourOfDayStamp;

	// if bestStamp is still UNSET, then take HOUR or AM_PM. (See 4846659)
	if (bestStamp == UNSET) {
	    bestStamp = Math.max(stamp[HOUR], stamp[AM_PM]);
	}

        // Hours
        if (bestStamp != UNSET) {
            if (bestStamp == hourOfDayStamp) {
		fieldMask |= HOUR_OF_DAY_MASK;
            } else {
		fieldMask |= HOUR_MASK;
		if (stamp[AM_PM] != UNSET) {
		    fieldMask |= AM_PM_MASK;
		}
            }
        }
	if (stamp[MINUTE] != UNSET) {
	    fieldMask |= MINUTE_MASK;
	}
	if (stamp[SECOND] != UNSET) {
	    fieldMask |= SECOND_MASK;
	}
	if (stamp[MILLISECOND] != UNSET) {
	    fieldMask |= MILLISECOND_MASK;
	}
	if (stamp[ZONE_OFFSET] >= MINIMUM_USER_STAMP) {
		fieldMask |= ZONE_OFFSET_MASK;
	}
	if (stamp[DST_OFFSET] >= MINIMUM_USER_STAMP) {
	    fieldMask |= DST_OFFSET_MASK;
	}

	return fieldMask;
    
public voidset(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.
param
field the given calendar field.
param
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
#set(int,int,int)
see
#set(int,int,int,int,int)
see
#set(int,int,int,int,int,int)
see
#get(int)
	if (isLenient() && areFieldsSet && !areAllFieldsSet) {
	    computeFields();
	}
	internalSet(field, value);
        isTimeSet = false;
	areFieldsSet = false;
        isSet[field] = true;
        stamp[field] = nextStamp++;
	if (nextStamp == Integer.MAX_VALUE) {
	    adjustStamp();
	}
    
public final voidset(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 {@link #clear()} first.
param
year the value used to set the YEAR calendar field.
param
month the value used to set the MONTH calendar field.
Month value is 0-based. e.g., 0 for January.
param
date the value used to set the DAY_OF_MONTH calendar field.
see
#set(int,int)
see
#set(int,int,int,int,int)
see
#set(int,int,int,int,int,int)
        set(YEAR, year);
        set(MONTH, month);
        set(DATE, date);
    
public final voidset(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 {@link #clear()} first.
param
year the value used to set the YEAR calendar field.
param
month the value used to set the MONTH calendar field.
Month value is 0-based. e.g., 0 for January.
param
date the value used to set the DAY_OF_MONTH calendar field.
param
hourOfDay the value used to set the HOUR_OF_DAY calendar field.
param
minute the value used to set the MINUTE calendar field.
see
#set(int,int)
see
#set(int,int,int)
see
#set(int,int,int,int,int,int)
        set(YEAR, year);
        set(MONTH, month);
        set(DATE, date);
        set(HOUR_OF_DAY, hourOfDay);
        set(MINUTE, minute);
    
public final voidset(int year, int month, int date, int hourOfDay, int minute, int second)
Sets the values for the fields YEAR, MONTH,
DAY_OF_MONTH, HOUR, MINUTE, and
SECOND.
Previous values of other fields are retained. If this is not desired,
call {@link #clear()} first.
param
year the value used to set the YEAR calendar field.
param
month the value used to set the MONTH calendar field.
Month value is 0-based. e.g., 0 for January.
param
date the value used to set the DAY_OF_MONTH calendar field.
param
hourOfDay the value used to set the HOUR_OF_DAY calendar field.
param
minute the value used to set the MINUTE calendar field.
param
second the value used to set the SECOND calendar field.
see
#set(int,int)
see
#set(int,int,int)
see
#set(int,int,int,int,int)
        set(YEAR, year);
        set(MONTH, month);
        set(DATE, date);
        set(HOUR_OF_DAY, hourOfDay);
        set(MINUTE, minute);
        set(SECOND, second);
    
final voidsetFieldsComputed(int fieldMask)
Sets the state of the specified calendar fields to
computed. This state means that the specified calendar fields
have valid values that have been set by internal time calculation
rather than by calling one of the setter methods.
param
fieldMask the field to be marked as computed.
exception
IndexOutOfBoundsException if the specified
field is out of range
(field < 0 || field >= FIELD_COUNT).
see
#isExternallySet(int)
see
#selectFields()
	if (fieldMask == ALL_FIELDS) {
	    for (int i = 0; i < fields.length; i++) {
		stamp[i] = COMPUTED;
		isSet[i] = true;
	    }
	    areFieldsSet = areAllFieldsSet = true;
	} else {
	    for (int i = 0; i < fields.length; i++) {
		if ((fieldMask & 1) == 1) {
		    stamp[i] = COMPUTED;
		    isSet[i] = true;
		} else {
		    if (areAllFieldsSet && !isSet[i]) {
			areAllFieldsSet = false;
		    }
		}
		fieldMask >>>= 1;
	    }
	}
    
final voidsetFieldsNormalized(int fieldMask)
Sets the state of the calendar fields that are not specified
by fieldMask to unset. If fieldMask
specifies all the calendar fields, then the state of this
Calendar becomes that all the calendar fields are in sync
with the time value (millisecond offset from the Epoch).
param
fieldMask the field mask indicating which calendar fields are in
sync with the time value.
exception
IndexOutOfBoundsException if the specified
field is out of range
(field < 0 || field >= FIELD_COUNT).
see
#isExternallySet(int)
see
#selectFields()
	if (fieldMask != ALL_FIELDS) {
	    for (int i = 0; i < fields.length; i++) {
		if ((fieldMask & 1) == 0) {
		    stamp[i] = fields[i] = 0; // UNSET == 0
		    isSet[i] = false;
		}
		fieldMask >>= 1;
	    }
	}

	// Some or all of the fields are in sync with the
	// milliseconds, but the stamp values are not normalized yet.
        areFieldsSet = true;
	areAllFieldsSet = false;
    
public voidsetFirstDayOfWeek(int value)
Sets what the first day of the week is; e.g., SUNDAY in the U.S.,
MONDAY in France.
param
value the given first day of the week.
see
#getFirstDayOfWeek()
see
#getMinimalDaysInFirstWeek()
	if (firstDayOfWeek == value) {
	    return;
	}
        firstDayOfWeek = value;
	invalidateWeekFields();
    
public voidsetLenient(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.
param
lenient true if the lenient mode is to be turned
on; false if it is to be turned off.
see
#isLenient()
see
java.text.DateFormat#setLenient
        this.lenient = lenient;
    
public voidsetMinimalDaysInFirstWeek(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.
param
value the given minimal days required in the first week
of the year.
see
#getMinimalDaysInFirstWeek()
        if (minimalDaysInFirstWeek == value) {
	    return;
	}
        minimalDaysInFirstWeek = value;
	invalidateWeekFields();
    
public final voidsetTime(java.util.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().
param
date the given Date.
see
#getTime()
see
#setTimeInMillis(long)
        setTimeInMillis(date.getTime());
    
public voidsetTimeInMillis(long millis)
Sets this Calendar's current time from the given long value.
param
millis the new time in UTC milliseconds from the epoch.
see
#setTime(Date)
see
#getTimeInMillis()
	// If we don't need to recalculate the calendar field values,
	// do nothing.
	if (time == millis && isTimeSet && areFieldsSet && areAllFieldsSet
	    && (zone instanceof ZoneInfo) && !((ZoneInfo)zone).isDirty()) {
	    return;
	}
        time = millis;
        isTimeSet = true;
        areFieldsSet = false;
	computeFields();
        areAllFieldsSet = areFieldsSet = true;
    
public voidsetTimeZone(java.util.TimeZone value)
Sets the time zone with the given time zone value.
param
value the given time zone.
        zone = value;
	sharedZone = false;
        /* Recompute the fields from the time using the new zone.  This also
         * works if isTimeSet is false (after a call to set()).  In that case
         * the time will be computed from the fields using the new zone, then
         * the fields will get recomputed from that.  Consider the sequence of
         * calls: cal.setTimeZone(EST); cal.set(HOUR, 1); cal.setTimeZone(PST).
         * Is cal set to 1 o'clock EST or 1 o'clock PST?  Answer: PST.  More
         * generally, a call to setTimeZone() affects calls to set() BEFORE AND
         * AFTER it up to the next call to complete().
         */
        areAllFieldsSet = areFieldsSet = false;
    
final voidsetUnnormalized()
Marks this Calendar as not sync'd.
	areFieldsSet = areAllFieldsSet = false;
    
private voidsetWeekCountData(java.util.Locale desiredLocale)
Both firstDayOfWeek and minimalDaysInFirstWeek are locale-dependent.
They are used to figure out the week count for a specific date for
a given locale. These must be set when a Calendar is constructed.
param
desiredLocale the given locale.
	/* try to get the Locale data from the cache */
	int[] data = cachedLocaleData.get(desiredLocale);
	if (data == null) {  /* cache miss */
	    ResourceBundle bundle = LocaleData.getCalendarData(desiredLocale);
	    data = new int[2];
	    data[0] = Integer.parseInt(bundle.getString("firstDayOfWeek"));
	    data[1] = Integer.parseInt(bundle.getString("minimalDaysInFirstWeek"));
	    cachedLocaleData.put(desiredLocale, data);
	}
	firstDayOfWeek = data[0];
	minimalDaysInFirstWeek = data[1];
    
voidsetZoneShared(boolean shared)
Sets the sharedZone flag to shared.
	sharedZone = shared;
    
public java.lang.StringtoString()
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.
return
a string representation of this calendar.
	// NOTE: BuddhistCalendar.toString() interprets the string
	// produced by this method so that the Gregorian year number
	// is substituted by its B.E. year value. It relies on
	// "...,YEAR=<year>,..." or "...,YEAR=?,...".
        StringBuilder buffer = new StringBuilder(800);
        buffer.append(getClass().getName()).append('[");
	appendValue(buffer, "time", isTimeSet, time);
        buffer.append(",areFieldsSet=").append(areFieldsSet);
        buffer.append(",areAllFieldsSet=").append(areAllFieldsSet);
        buffer.append(",lenient=").append(lenient);
        buffer.append(",zone=").append(zone);
        appendValue(buffer, ",firstDayOfWeek", true, (long) firstDayOfWeek);
        appendValue(buffer, ",minimalDaysInFirstWeek", true, (long) minimalDaysInFirstWeek);
        for (int i = 0; i < FIELD_COUNT; ++i) {
            buffer.append(',");
	    appendValue(buffer, FIELD_NAME[i], isSet(i), (long) fields[i]);
        }
        buffer.append(']");
        return buffer.toString();
    
private voidupdateTime()
Recomputes the time and updates the status fields isTimeSet
and areFieldsSet. Callers should check isTimeSet and only
call this method if isTimeSet is false.
        computeTime();
	// The areFieldsSet and areAllFieldsSet values are no longer
	// controlled here (as of 1.5).
        isTimeSet = true;
    
private voidwriteObject(java.io.ObjectOutputStream stream)
Save the state of this object to a stream (i.e., serialize it).

Ideally, Calendar would only write out its state data and
the current time, and not write any field data out, such as
fields[], isTimeSet, areFieldsSet,
and isSet[]. nextStamp also should not be part
of the persistent state. Unfortunately, this didn't happen before JDK 1.1
shipped. To be compatible with JDK 1.1, we will always have to write out
the field values and state flags. However, nextStamp can be
removed from the serialization stream; this will probably happen in the
near future.
        // Try to compute the time correctly, for the future (stream
        // version 2) in which we don't write out fields[] or isSet[].
        if (!isTimeSet) {
            try {
                updateTime();
            }
            catch (IllegalArgumentException e) {}
        }

	// If this Calendar has a ZoneInfo, save it and set a
	// SimpleTimeZone equivalent (as a single DST schedule) for
	// backward compatibility.
	TimeZone savedZone = null;
	if (zone instanceof ZoneInfo) {
	    SimpleTimeZone stz = ((ZoneInfo)zone).getLastRuleInstance();
	    if (stz == null) {
		stz = new SimpleTimeZone(zone.getRawOffset(), zone.getID());
	    }
	    savedZone = zone;
	    zone = stz;
	}

        // Write out the 1.1 FCS object.
        stream.defaultWriteObject();

	// Write out the ZoneInfo object
	// 4802409: we write out even if it is null, a temporary workaround
	// the real fix for bug 4844924 in corba-iiop
	stream.writeObject(savedZone);
	if (savedZone != null) {
	    zone = savedZone;
	}