java.util
Class GregorianCalendar

java.lang.Object
  |
  +--java.util.Calendar
        |
        +--java.util.GregorianCalendar
public class GregorianCalendar
extends Calendar

GregorianCalendar is a concrete subclass of Calendar and provides the standard calendar used by most of the world.

The standard (Gregorian) calendar has 2 eras, BC and AD.

This implementation handles a single discontinuity, which corresponds by default to the date the Gregorian calendar was instituted (October 15, 1582 in some countries, later in others). The cutover date may be changed by the caller by calling setGregorianChange().

Historically, in those countries which adopted the Gregorian calendar first, October 4, 1582 was thus followed by October 15, 1582. This calendar models this correctly. Before the Gregorian cutover, GregorianCalendar implements the Julian calendar. The only difference between the Gregorian and the Julian calendar is the leap year rule. The Julian calendar specifies leap years every four years, whereas the Gregorian calendar omits century years which are not divisible by 400.

GregorianCalendar implements proleptic Gregorian and Julian calendars. That is, dates are computed by extrapolating the current rules indefinitely far backward and forward in time. As a result, GregorianCalendar may be used for all years to generate meaningful and consistent results. However, dates obtained using GregorianCalendar are historically accurate only from March 1, 4 AD onward, when modern Julian calendar rules were adopted. Before this date, leap year rules were applied irregularly, and before 45 BC the Julian calendar did not even exist.

Prior to the institution of the Gregorian calendar, New Year's Day was March 25. To avoid confusion, this calendar always uses January 1. A manual adjustment may be made if desired for dates that are prior to the Gregorian changeover and which fall between January 1 and March 24.

Example: 

 // get the supported ids for GMT-08:00 (Pacific Standard Time)
 String[] ids = TimeZone.getAvailableIDs(-8 * 60 * 60 * 1000);
 // if no ids were returned, something is wrong. get out.
 if (ids.length == 0)
     System.exit(0);

  // begin output
 System.out.println("Current Time");

 // create a Pacific Standard Time time zone
 SimpleTimeZone pdt = new SimpleTimeZone(-8 * 60 * 60 * 1000, ids[0]);

 // set up rules for daylight savings time
 pdt.setStartRule(Calendar.APRIL, 1, Calendar.SUNDAY, 2 * 60 * 60 * 1000);
 pdt.setEndRule(Calendar.OCTOBER, -1, Calendar.SUNDAY, 2 * 60 * 60 * 1000);

 // create a GregorianCalendar with the Pacific Daylight time zone
 // and the current date and time
 Calendar calendar = new GregorianCalendar(pdt);
 Date trialTime = new Date();
 calendar.setTime(trialTime);

 // print out a bunch of interesting things
 System.out.println("ERA: " + calendar.get(Calendar.ERA));
 System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
 System.out.println("MONTH: " + calendar.get(Calendar.MONTH));
 System.out.println("WEEK_OF_YEAR: " + calendar.get(Calendar.WEEK_OF_YEAR));
 System.out.println("WEEK_OF_MONTH: " + calendar.get(Calendar.WEEK_OF_MONTH));
 System.out.println("DATE: " + calendar.get(Calendar.DATE));
 System.out.println("DAY_OF_MONTH: " + calendar.get(Calendar.DAY_OF_MONTH));
 System.out.println("DAY_OF_YEAR: " + calendar.get(Calendar.DAY_OF_YEAR));
 System.out.println("DAY_OF_WEEK: " + calendar.get(Calendar.DAY_OF_WEEK));
 System.out.println("DAY_OF_WEEK_IN_MONTH: "
                    + calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
 System.out.println("AM_PM: " + calendar.get(Calendar.AM_PM));
 System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
 System.out.println("HOUR_OF_DAY: " + calendar.get(Calendar.HOUR_OF_DAY));
 System.out.println("MINUTE: " + calendar.get(Calendar.MINUTE));
 System.out.println("SECOND: " + calendar.get(Calendar.SECOND));
 System.out.println("MILLISECOND: " + calendar.get(Calendar.MILLISECOND));
 System.out.println("ZONE_OFFSET: "
                    + (calendar.get(Calendar.ZONE_OFFSET)/(60*60*1000)));
 System.out.println("DST_OFFSET: "
                    + (calendar.get(Calendar.DST_OFFSET)/(60*60*1000)));

 System.out.println("Current Time, with hour reset to 3");
 calendar.clear(Calendar.HOUR_OF_DAY); // so doesn't override
 calendar.set(Calendar.HOUR, 3);
 System.out.println("ERA: " + calendar.get(Calendar.ERA));
 System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
 System.out.println("MONTH: " + calendar.get(Calendar.MONTH));
 System.out.println("WEEK_OF_YEAR: " + calendar.get(Calendar.WEEK_OF_YEAR));
 System.out.println("WEEK_OF_MONTH: " + calendar.get(Calendar.WEEK_OF_MONTH));
 System.out.println("DATE: " + calendar.get(Calendar.DATE));
 System.out.println("DAY_OF_MONTH: " + calendar.get(Calendar.DAY_OF_MONTH));
 System.out.println("DAY_OF_YEAR: " + calendar.get(Calendar.DAY_OF_YEAR));
 System.out.println("DAY_OF_WEEK: " + calendar.get(Calendar.DAY_OF_WEEK));
 System.out.println("DAY_OF_WEEK_IN_MONTH: "
                    + calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
 System.out.println("AM_PM: " + calendar.get(Calendar.AM_PM));
 System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
 System.out.println("HOUR_OF_DAY: " + calendar.get(Calendar.HOUR_OF_DAY));
 System.out.println("MINUTE: " + calendar.get(Calendar.MINUTE));
 System.out.println("SECOND: " + calendar.get(Calendar.SECOND));
 System.out.println("MILLISECOND: " + calendar.get(Calendar.MILLISECOND));
 System.out.println("ZONE_OFFSET: "
        + (calendar.get(Calendar.ZONE_OFFSET)/(60*60*1000))); // in hours
 System.out.println("DST_OFFSET: "
        + (calendar.get(Calendar.DST_OFFSET)/(60*60*1000))); // in hours

See Also:
Calendar, TimeZone, Serialized Form

Field Summary
static int AD
          Value of the ERA field indicating the common era (Anno Domini), also known as CE.
static int BC
          Value of the ERA field indicating the period before the common era (before Christ), also known as BCE.
private static int EPOCH_JULIAN_DAY
           
private static int EPOCH_YEAR
           
private  long gregorianCutover
          The point at which the Gregorian calendar rules are used, measured in milliseconds from the standard epoch.
private  int gregorianCutoverYear
          The year of the gregorianCutover, with 0 representing 1 BC, -1 representing 2 BC, etc.
private static int JAN_1_1_JULIAN_DAY
           
private static int[] LEAP_MONTH_LENGTH
           
private static int[] LEAP_NUM_DAYS
           
private static int[] LEAST_MAX_VALUES
           
private static int[] MAX_VALUES
           
private static int[] MIN_VALUES
           
private static int[] MONTH_LENGTH
           
private  long normalizedGregorianCutover
          Midnight, local time (using this Calendar's TimeZone) at or before the gregorianCutover.
private static int[] NUM_DAYS
           
private static long ONE_DAY
           
private static int ONE_HOUR
           
private static int ONE_MINUTE
           
private static int ONE_SECOND
           
private static long ONE_WEEK
           
(package private) static long serialVersionUID
           
 
Fields inherited from class java.util.Calendar
AM, AM_PM, APRIL, areAllFieldsSet, areFieldsSet, AUGUST, cachedLocaleData, currentSerialVersion, DATE, DAY_OF_MONTH, DAY_OF_WEEK, DAY_OF_WEEK_IN_MONTH, DAY_OF_YEAR, DECEMBER, DST_OFFSET, ERA, FEBRUARY, FIELD_COUNT, FIELD_NAME, fields, firstDayOfWeek, FRIDAY, HOUR, HOUR_OF_DAY, INTERNALLY_SET, isSet, isTimeSet, JANUARY, JULY, JUNE, lenient, MARCH, MAY, MILLISECOND, minimalDaysInFirstWeek, MINIMUM_USER_STAMP, MINUTE, MONDAY, MONTH, nextStamp, NOVEMBER, OCTOBER, PM, SATURDAY, SECOND, SEPTEMBER, serialVersionOnStream, serialVersionUID, stamp, SUNDAY, THURSDAY, time, TUESDAY, UNDECIMBER, UNSET, WEDNESDAY, WEEK_OF_MONTH, WEEK_OF_YEAR, YEAR, zone, ZONE_OFFSET
 
Constructor Summary
GregorianCalendar()
          Constructs a default GregorianCalendar using the current time in the default time zone with the default locale.
GregorianCalendar(int year, int month, int date)
          Constructs a GregorianCalendar with the given date set in the default time zone with the default locale.
GregorianCalendar(int year, int month, int date, int hour, int minute)
          Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.
GregorianCalendar(int year, int month, int date, int hour, int minute, int second)
          Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.
GregorianCalendar(Locale aLocale)
          Constructs a GregorianCalendar based on the current time in the default time zone with the given locale.
GregorianCalendar(TimeZone zone)
          Constructs a GregorianCalendar based on the current time in the given time zone with the default locale.
GregorianCalendar(TimeZone zone, Locale aLocale)
          Constructs a GregorianCalendar based on the current time in the given time zone with the given locale.
 
Method Summary
 void add(int field, int amount)
          Overrides Calendar Date Arithmetic function.
private static int aggregateStamp(int stamp_a, int stamp_b)
          Return the pseudo-time-stamp for two fields, given their individual pseudo-time-stamps.
private  boolean boundsCheck(int value, int field)
          Validates the value of the given time field.
protected  void computeFields()
          Overrides Calendar Converts UTC as milliseconds to time field values.
private  long computeJulianDay(boolean isGregorian, int year)
          Compute the Julian day number under either the Gregorian or the Julian calendar, using the given year and the remaining fields.
protected  void computeTime()
          Overrides Calendar Converts time field values to UTC as milliseconds.
 boolean equals(Object obj)
          Compares this GregorianCalendar to an object reference.
private static int floorDivide(int numerator, int denominator)
          Divide two integers, returning the floor of the quotient.
private static int floorDivide(int numerator, int denominator, int[] remainder)
          Divide two integers, returning the floor of the quotient, and the modulus remainder.
private static int floorDivide(long numerator, int denominator, int[] remainder)
          Divide two integers, returning the floor of the quotient, and the modulus remainder.
private static long floorDivide(long numerator, long denominator)
          Divide two long integers, returning the floor of the quotient.
 int getActualMaximum(int field)
          Return the maximum value that this field could have, given the current date.
 int getActualMinimum(int field)
          Return the minimum value that this field could have, given the current date.
private  long getEpochDay()
          Return the day number with respect to the epoch.
 int getGreatestMinimum(int field)
          Returns highest minimum value for the given field if varies.
 Date getGregorianChange()
          Gets the Gregorian Calendar change date.
(package private)  int getISOYear()
          Return the year that corresponds to the WEEK_OF_YEAR field.
 int getLeastMaximum(int field)
          Returns lowest maximum value for the given field if varies.
 int getMaximum(int field)
          Returns maximum value for the given field.
 int getMinimum(int field)
          Returns minimum value for the given field.
 int hashCode()
          Override hashCode.
(package private)  boolean inDaylightTime()
          Return true if the current time for this Calendar is in Daylignt Savings Time.
 boolean isLeapYear(int year)
          Determines if the given year is a leap year.
private static int julianDayToDayOfWeek(long julian)
           
private static long julianDayToMillis(long julian)
          Converts Julian day to time as milliseconds.
private static long millisToJulianDay(long millis)
          Converts time as milliseconds to Julian day.
private  int monthLength(int month)
           
private  int monthLength(int month, int year)
           
private  void pinDayOfMonth()
          After adjustments such as add(MONTH), add(YEAR), we don't want the month to jump around.
 void roll(int field, boolean up)
          Overrides Calendar Time Field Rolling function.
 void roll(int field, int amount)
          Roll a field by a signed amount.
 void setGregorianChange(Date date)
          Sets the GregorianCalendar change date.
private  void timeToFields(long theTime, boolean quick)
          Convert the time as milliseconds to the date fields.
private  boolean validateFields()
          Validates the values of the set time fields.
private  int weekNumber(int dayOfPeriod, int dayOfWeek)
          Return the week number of a day, within a period.
private  int yearLength()
           
private  int yearLength(int year)
           
 
Methods inherited from class java.util.Calendar
after, before, clear, clear, clone, complete, get, getAvailableLocales, getFirstDayOfWeek, getInstance, getInstance, getInstance, getInstance, getMinimalDaysInFirstWeek, getTime, getTimeInMillis, getTimeZone, internalGet, internalSet, isLenient, isSet, readObject, set, set, set, set, setFirstDayOfWeek, setLenient, setMinimalDaysInFirstWeek, setTime, setTimeInMillis, setTimeZone, setWeekCountData, toString, updateTime, writeObject
 
Methods inherited from class java.lang.Object
, finalize, getClass, notify, notifyAll, registerNatives, wait, wait, wait
 

Field Detail

BC

public static final int BC
Value of the ERA field indicating the period before the common era (before Christ), also known as BCE. The sequence of years at the transition from BC to AD is ..., 2 BC, 1 BC, 1 AD, 2 AD,...
See Also:
Calendar.ERA

AD

public static final int AD
Value of the ERA field indicating the common era (Anno Domini), also known as CE. The sequence of years at the transition from BC to AD is ..., 2 BC, 1 BC, 1 AD, 2 AD,...
See Also:
Calendar.ERA

JAN_1_1_JULIAN_DAY

private static final int JAN_1_1_JULIAN_DAY

EPOCH_JULIAN_DAY

private static final int EPOCH_JULIAN_DAY

EPOCH_YEAR

private static final int EPOCH_YEAR

NUM_DAYS

private static final int[] NUM_DAYS

LEAP_NUM_DAYS

private static final int[] LEAP_NUM_DAYS

MONTH_LENGTH

private static final int[] MONTH_LENGTH

LEAP_MONTH_LENGTH

private static final int[] LEAP_MONTH_LENGTH

ONE_SECOND

private static final int ONE_SECOND

ONE_MINUTE

private static final int ONE_MINUTE

ONE_HOUR

private static final int ONE_HOUR

ONE_DAY

private static final long ONE_DAY

ONE_WEEK

private static final long ONE_WEEK

MIN_VALUES

private static final int[] MIN_VALUES

LEAST_MAX_VALUES

private static final int[] LEAST_MAX_VALUES

MAX_VALUES

private static final int[] MAX_VALUES

gregorianCutover

private long gregorianCutover
The point at which the Gregorian calendar rules are used, measured in milliseconds from the standard epoch. Default is October 15, 1582 (Gregorian) 00:00:00 UTC or -12219292800000L. For this value, October 4, 1582 (Julian) is followed by October 15, 1582 (Gregorian). This corresponds to Julian day number 2299161.

normalizedGregorianCutover

private transient long normalizedGregorianCutover
Midnight, local time (using this Calendar's TimeZone) at or before the gregorianCutover. This is a pure date value with no time of day or timezone component.

gregorianCutoverYear

private transient int gregorianCutoverYear
The year of the gregorianCutover, with 0 representing 1 BC, -1 representing 2 BC, etc.

serialVersionUID

static final long serialVersionUID
Constructor Detail

GregorianCalendar

public GregorianCalendar()
Constructs a default GregorianCalendar using the current time in the default time zone with the default locale.

GregorianCalendar

public GregorianCalendar(TimeZone zone)
Constructs a GregorianCalendar based on the current time in the given time zone with the default locale.
Parameters:
zone - the given time zone.

GregorianCalendar

public GregorianCalendar(Locale aLocale)
Constructs a GregorianCalendar based on the current time in the default time zone with the given locale.
Parameters:
aLocale - the given locale.

GregorianCalendar

public GregorianCalendar(TimeZone zone,
                         Locale aLocale)
Constructs a GregorianCalendar based on the current time in the given time zone with the given locale.
Parameters:
zone - the given time zone.
aLocale - the given locale.

GregorianCalendar

public GregorianCalendar(int year,
                         int month,
                         int date)
Constructs a GregorianCalendar with the given date set in the default time zone with the default locale.
Parameters:
year - the value used to set the YEAR time field in the calendar.
month - the value used to set the MONTH time field in the calendar. Month value is 0-based. e.g., 0 for January.
date - the value used to set the DATE time field in the calendar.

GregorianCalendar

public GregorianCalendar(int year,
                         int month,
                         int date,
                         int hour,
                         int minute)
Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.
Parameters:
year - the value used to set the YEAR time field in the calendar.
month - the value used to set the MONTH time field in the calendar. Month value is 0-based. e.g., 0 for January.
date - the value used to set the DATE time field in the calendar.
hour - the value used to set the HOUR_OF_DAY time field in the calendar.
minute - the value used to set the MINUTE time field in the calendar.

GregorianCalendar

public GregorianCalendar(int year,
                         int month,
                         int date,
                         int hour,
                         int minute,
                         int second)
Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.
Parameters:
year - the value used to set the YEAR time field in the calendar.
month - the value used to set the MONTH time field in the calendar. Month value is 0-based. e.g., 0 for January.
date - the value used to set the DATE time field in the calendar.
hour - the value used to set the HOUR_OF_DAY time field in the calendar.
minute - the value used to set the MINUTE time field in the calendar.
second - the value used to set the SECOND time field in the calendar.
Method Detail

setGregorianChange

public void setGregorianChange(Date date)
Sets the GregorianCalendar change date. This is the point when the switch from Julian dates to Gregorian dates occurred. Default is October 15, 1582. Previous to this, dates will be in the Julian calendar.

To obtain a pure Julian calendar, set the change date to Date(Long.MAX_VALUE). To obtain a pure Gregorian calendar, set the change date to Date(Long.MIN_VALUE).

Parameters:
date - the given Gregorian cutover date.

getGregorianChange

public final Date getGregorianChange()
Gets the Gregorian Calendar change date. This is the point when the switch from Julian dates to Gregorian dates occurred. Default is October 15, 1582. Previous to this, dates will be in the Julian calendar.
Returns:
the Gregorian cutover date for this calendar.

isLeapYear

public boolean isLeapYear(int year)
Determines if the given year is a leap year. Returns true if the given year is a leap year.
Parameters:
year - the given year.
Returns:
true if the given year is a leap year; false otherwise.

equals

public boolean equals(Object obj)
Compares this GregorianCalendar to an object reference.
Parameters:
obj - the object reference with which to compare
Returns:
true if this object is equal to obj; false otherwise
Overrides:
equals in class Calendar

hashCode

public int hashCode()
Override hashCode. Generates the hash code for the GregorianCalendar object
Overrides:
hashCode in class Calendar

add

public void add(int field,
                int amount)
Overrides Calendar Date Arithmetic function. Adds the specified (signed) amount of time to the given time field, based on the calendar's rules.
Parameters:
field - the time field.
amount - the amount of date or time to be added to the field.
Throws:
IllegalArgumentException - if an unknown field is given.
Overrides:
add in class Calendar

roll

public void roll(int field,
                 boolean up)
Overrides Calendar Time Field Rolling function. Rolls (up/down) a single unit of time on the given time field.
Parameters:
field - the time field.
up - Indicates if rolling up or rolling down the field value.
Throws:
IllegalArgumentException - if an unknown field value is given.
Overrides:
roll in class Calendar

roll

public void roll(int field,
                 int amount)
Roll a field by a signed amount.
Overrides:
roll in class Calendar

getMinimum

public int getMinimum(int field)
Returns minimum value for the given field. e.g. for Gregorian DAY_OF_MONTH, 1 Please see Calendar.getMinimum for descriptions on parameters and the return value.
Overrides:
getMinimum in class Calendar

getMaximum

public int getMaximum(int field)
Returns maximum value for the given field. e.g. for Gregorian DAY_OF_MONTH, 31 Please see Calendar.getMaximum for descriptions on parameters and the return value.
Overrides:
getMaximum in class Calendar

getGreatestMinimum

public int getGreatestMinimum(int field)
Returns highest minimum value for the given field if varies. Otherwise same as getMinimum(). For Gregorian, no difference. Please see Calendar.getGreatestMinimum for descriptions on parameters and the return value.
Overrides:
getGreatestMinimum in class Calendar

getLeastMaximum

public int getLeastMaximum(int field)
Returns lowest maximum value for the given field if varies. Otherwise same as getMaximum(). For Gregorian DAY_OF_MONTH, 28 Please see Calendar.getLeastMaximum for descriptions on parameters and the return value.
Overrides:
getLeastMaximum in class Calendar

getActualMinimum

public int getActualMinimum(int field)
Return the minimum value that this field could have, given the current date. For the Gregorian calendar, this is the same as getMinimum() and getGreatestMinimum().
Overrides:
getActualMinimum in class Calendar

getActualMaximum

public int getActualMaximum(int field)
Return the maximum value that this field could have, given the current date. For example, with the date "Feb 3, 1997" and the DAY_OF_MONTH field, the actual maximum would be 28; for "Feb 3, 1996" it s 29. Similarly for a Hebrew calendar, for some years the actual maximum for MONTH is 12, and for others 13.
Overrides:
getActualMaximum in class Calendar

inDaylightTime

boolean inDaylightTime()
Return true if the current time for this Calendar is in Daylignt Savings Time. Note -- MAKE THIS PUBLIC AT THE NEXT API CHANGE. POSSIBLY DEPRECATE AND REMOVE TimeZone.inDaylightTime().

getISOYear

int getISOYear()
Return the year that corresponds to the WEEK_OF_YEAR field. This may be one year before or after the calendar year stored in the YEAR field. For example, January 1, 1999 is considered Friday of week 53 of 1998 (if minimal days in first week is 2 or less, and the first day of the week is Sunday). Given these same settings, the ISO year of January 1, 1999 is 1998.

Warning: This method will complete all fields.

Returns:
the year corresponding to the WEEK_OF_YEAR field, which may be one year before or after the YEAR field.
See Also:
Calendar.WEEK_OF_YEAR

computeFields

protected void computeFields()
Overrides Calendar Converts UTC as milliseconds to time field values. The time is not recomputed first; to recompute the time, then the fields, call the complete method.
Overrides:
computeFields in class Calendar
See Also:
Calendar.complete()

timeToFields

private final void timeToFields(long theTime,
                                boolean quick)
Convert the time as milliseconds to the date fields. Millis must be given as local wall millis to get the correct local day. For example, if it is 11:30 pm Standard, and DST is in effect, the correct DST millis must be passed in to get the right date.

Fields that are completed by this method: ERA, YEAR, MONTH, DATE, DAY_OF_WEEK, DAY_OF_YEAR, WEEK_OF_YEAR, WEEK_OF_MONTH, DAY_OF_WEEK_IN_MONTH.

Parameters:
theTime - the time in wall millis (either Standard or DST), whichever is in effect
quick - if true, only compute the ERA, YEAR, MONTH, DATE, DAY_OF_WEEK, and DAY_OF_YEAR.

computeTime

protected void computeTime()
Overrides Calendar Converts time field values to UTC as milliseconds.
Throws:
IllegalArgumentException - if any fields are invalid.
Overrides:
computeTime in class Calendar

computeJulianDay

private final long computeJulianDay(boolean isGregorian,
                                    int year)
Compute the Julian day number under either the Gregorian or the Julian calendar, using the given year and the remaining fields.
Parameters:
isGregorian - if true, use the Gregorian calendar
year - the adjusted year number, with 0 indicating the year 1 BC, -1 indicating 2 BC, etc.
Returns:
the Julian day number

millisToJulianDay

private static final long millisToJulianDay(long millis)
Converts time as milliseconds to Julian day.
Parameters:
millis - the given milliseconds.
Returns:
the Julian day number.

julianDayToMillis

private static final long julianDayToMillis(long julian)
Converts Julian day to time as milliseconds.
Parameters:
julian - the given Julian day number.
Returns:
time as milliseconds.

julianDayToDayOfWeek

private static final int julianDayToDayOfWeek(long julian)

floorDivide

private static final long floorDivide(long numerator,
                                      long denominator)
Divide two long integers, returning the floor of the quotient.

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

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

floorDivide

private static final int floorDivide(int numerator,
                                     int denominator)
Divide two integers, returning the floor of the quotient.

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

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

floorDivide

private static final int floorDivide(int numerator,
                                     int denominator,
                                     int[] remainder)
Divide two integers, returning the floor of the quotient, and the modulus remainder.

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

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

floorDivide

private static final int floorDivide(long numerator,
                                     int denominator,
                                     int[] remainder)
Divide two integers, returning the floor of the quotient, and the modulus remainder.

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

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

aggregateStamp

private static final int aggregateStamp(int stamp_a,
                                        int stamp_b)
Return 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.

weekNumber

private final int weekNumber(int dayOfPeriod,
                             int dayOfWeek)
Return the week number of a day, within a period. This may be the week number in a year, or the week number in a month. Usually this will be a value >= 1, but if some initial days of the period are excluded from week 1, because minimalDaysInFirstWeek is > 1, then the week number will be zero for those initial days. Requires the day of week for the given date in order to determine the day of week of the first day of the period.
Parameters:
dayOfPeriod - Day-of-year or day-of-month. Should be 1 for first day of period.
day - Day-of-week for given dayOfPeriod. 1-based with 1=Sunday.
Returns:
Week number, one-based, or zero if the day falls in part of the month before the first week, when there are days before the first week because the minimum days in the first week is more than one.

monthLength

private final int monthLength(int month,
                              int year)

monthLength

private final int monthLength(int month)

yearLength

private final int yearLength(int year)

yearLength

private final int yearLength()

pinDayOfMonth

private final void pinDayOfMonth()
After adjustments such as add(MONTH), add(YEAR), we don't want the month to jump around. E.g., we don't want Jan 31 + 1 month to go to Mar 3, we want it to go to Feb 28. Adjustments which might run into this problem call this method to retain the proper month.

validateFields

private boolean validateFields()
Validates the values of the set time fields.

boundsCheck

private final boolean boundsCheck(int value,
                                  int field)
Validates the value of the given time field.

getEpochDay

private final long getEpochDay()
Return the day number with respect to the epoch. January 1, 1970 (Gregorian) is day zero.