Contents | Package | Class | Tree | Deprecated | Index | Help Java 1.2 Beta 3
PREV | NEXT SHOW LISTS | HIDE LISTS

Class java.util.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). This cutover date may be changed by the caller.

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

Field Summary
static int  AD
Useful constant for GregorianCalendar.
static int  BC
Useful constant for GregorianCalendar.
 
Fields inherited from class java.util.Calendar
 AM, AM_PM, APRIL, areFieldsSet, AUGUST, DATE, DAY_OF_MONTH, DAY_OF_WEEK, DAY_OF_WEEK_IN_MONTH, DAY_OF_YEAR, DECEMBER, DST_OFFSET, ERA, FEBRUARY, FIELD_COUNT, fields, FRIDAY, HOUR, HOUR_OF_DAY, isSet, isTimeSet, JANUARY, JULY, JUNE, MARCH, MAY, MILLISECOND, MINUTE, MONDAY, MONTH, NOVEMBER, OCTOBER, PM, SATURDAY, SECOND, SEPTEMBER, SUNDAY, THURSDAY, time, TUESDAY, UNDECIMBER, WEDNESDAY, WEEK_OF_MONTH, WEEK_OF_YEAR, YEAR, ZONE_OFFSET
 

Constructor Summary
 GregorianCalendar()
Constructs a default GregorianCalendar using the current time in the default time zone with the default locale.
 GregorianCalendar(TimeZone zone)
Constructs a GregorianCalendar based on the current time in the given 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, Locale aLocale)
Constructs a GregorianCalendar based on the current time in the given time zone with the given 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.
 

Method Summary
void  add(int field, int amount)
Overrides Calendar Date Arithmetic function.
void  computeFields()
Overrides Calendar Converts UTC as milliseconds to time field values.
void  computeTime()
Overrides Calendar Converts time field values to UTC as milliseconds.
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.
int  getGreatestMinimum(int field)
Returns highest minimum value for the given field if varies.
Date  getGregorianChange()
Gets the Gregorian Calendar change date.
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.
boolean  isLeapYear(int year)
Determines if the given year is a leap year.
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.
 
Methods inherited from class java.util.Calendar
 add, after, before, clear, clear, clone, complete, computeFields, computeTime, equals, get, getAvailableLocales, getFirstDayOfWeek, getGreatestMinimum, getInstance, getInstance, getInstance, getInstance, getLeastMaximum, getMaximum, getMinimalDaysInFirstWeek, getMinimum, getTime, getTimeInMillis, getTimeZone, internalGet, isLenient, isSet, roll, roll, set, set, set, set, setFirstDayOfWeek, setLenient, setMinimalDaysInFirstWeek, setTime, setTimeInMillis, setTimeZone, toString
 
Methods inherited from class java.lang.Object
 clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

BC

public static final int BC
Useful constant for GregorianCalendar.

AD

public static final int AD
Useful constant for GregorianCalendar.
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 00:00:00 local time, October 15, 1582. Previous to this time and date will be Julian dates.
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 00:00:00 local time, October 15, 1582. Previous to this time and date will be Julian dates.
Returns:
the Gregorian cutover time 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.

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:
complete

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

hashCode

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

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

Contents | Package | Class | Tree | Deprecated | Index | Help Java 1.2 Beta 3
PREV | NEXT SHOW LISTS | HIDE LISTS

Submit a bug or feature
Submit comments/suggestions about new javadoc look.
Java is a trademark or registered trademark of Sun Microsystems, Inc. in the US and other countries.
Copyright 1993-1998 Sun Microsystems, Inc. 901 San Antonio Road, Palo Alto, California, 94303, U.S.A. All Rights Reserved.