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Class java.util.GregorianCalendar 

java.lang.Object
   |
   +----java.util.Calendar
           |
           +----java.util.GregorianCalendar
public class GregorianCalendar
extends Calendar
Concrete class which provides the standard calendar used by most of the world.

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

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: 

 System.out.println("Current Time");
 SimpleTimeZone pdt = new SimpleTimeZone(-8 * 60 * 60 * 1000);
 pdt.setStartRule(Calendar.APRIL, 1, Calendar.SUNDAY, 2 * 60 * 60 * 1000);
 pdt.setEndRule(Calendar.OCTOBER, -1, Calendar.SUNDAY, 2 * 60 * 60 * 1000);
 Calendar calendar = new GregorianCalendar(pdt);
 Date trialTime = new Date();
 calendar.setTime(trialTime);
 calendar.computeFields();
 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("WEEKOFYEAR: " + calendar.get(Calendar.WEEKOFYEAR));
 System.out.println("WEEKOFMONTH: " + calendar.get(Calendar.WEEKOFMONTH));
 System.out.println("DATE: " + calendar.get(Calendar.DATE));
 System.out.println("DAYOFMONTH: " + calendar.get(Calendar.DAYOFMONTH));
 System.out.println("DAYOFYEAR: " + calendar.get(Calendar.DAYOFYEAR));
 System.out.println("DAYOFWEEK: " + calendar.get(Calendar.DAYOFWEEK));
 System.out.println("DAYOFWEEKINMONTH: "
                    + calendar.get(Calendar.DAYOFWEEKINMONTH));
 System.out.println("AMPM: " + calendar.get(Calendar.AMPM));
 System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
 System.out.println("HOUROFDAY: " + calendar.get(Calendar.HOUROFDAY));
 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("ZONEOFFSET: "
                    + (calendar.get(Calendar.ZONEOFFSET)/(60*60*1000)));
 System.out.println("DSTOFFSET: "
                    + (calendar.get(Calendar.DSTOFFSET)/(60*60*1000)));
 System.out.println("Current Time, with hour reset to 3");
 calendar.clear(Calendar.HOUROFDAY); // so doesn't override
 calendar.set(Calendar.HOUR, 3);
 calendar.computeFields();
 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("WEEKOFYEAR: " + calendar.get(Calendar.WEEKOFYEAR));
 System.out.println("WEEKOFMONTH: " + calendar.get(Calendar.WEEKOFMONTH));
 System.out.println("DATE: " + calendar.get(Calendar.DATE));
 System.out.println("DAYOFMONTH: " + calendar.get(Calendar.DAYOFMONTH));
 System.out.println("DAYOFYEAR: " + calendar.get(Calendar.DAYOFYEAR));
 System.out.println("DAYOFWEEK: " + calendar.get(Calendar.DAYOFWEEK));
 System.out.println("DAYOFWEEKINMONTH: "
                    + calendar.get(Calendar.DAYOFWEEKINMONTH));
 System.out.println("AMPM: " + calendar.get(Calendar.AMPM));
 System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
 System.out.println("HOUROFDAY: " + calendar.get(Calendar.HOUROFDAY));
 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("ZONEOFFSET: "
        + (calendar.get(Calendar.ZONEOFFSET)/(60*60*1000))); // in hours
 System.out.println("DSTOFFSET: "
        + (calendar.get(Calendar.DSTOFFSET)/(60*60*1000))); // in hours

See Also:
Calendar, TimeZone

Variable Index

o AD
Useful constant for GregorianCalendar.
o BC
Useful constant for GregorianCalendar.

Constructor Index

o GregorianCalendar()
Constructs a default GregorianCalendar using the current time in the default time zone with the default locale.
o GregorianCalendar(int, int, int)
Constructs a GregorianCalendar with the given date set in the default time zone with the default locale.
o GregorianCalendar(int, int, int, int, int)
Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.
o GregorianCalendar(int, int, int, int, int, int)
Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.
o GregorianCalendar(Locale)
Constructs a GregorianCalendar based on the current time in the default time zone with the given locale.
o GregorianCalendar(TimeZone)
Constructs a GregorianCalendar based on the current time in the given time zone with the default locale.
o GregorianCalendar(TimeZone, Locale)
Constructs a GregorianCalendar based on the current time in the given time zone with the given locale.

Method Index

o add(byte, int)
Overrides Calendar Date Arithmetic function.
o after(Object)
Overrides Calendar Compares the time field records.
o before(Object)
Overrides Calendar Compares the time field records.
o clone()
Overrides Cloneable
o computeFields()
Overrides Calendar Converts UTC as milliseconds to time field values.
o computeTime()
Overrides Calendar Converts time field values to UTC as milliseconds.
o equals(Object)
Overrides Calendar Compares the time field records.
o getGreatestMinimum(byte)
Returns highest minimum value for the given field if varies.
o getGregorianChange()
Gets the Gregorian Calendar change date.
o getLeastMaximum(byte)
Returns lowest maximum value for the given field if varies.
o getMaximum(byte)
Returns maximum value for the given field.
o getMinimum(byte)
Returns minimum value for the given field.
o hashCode()
Override hashCode.
o isLeapYear(int)
Determines if the given year is a leap year.
o roll(byte, boolean)
Overrides Calendar Time Field Rolling function.
o setGregorianChange(Date)
Sets the GregorianCalendar change date.

Variables

o AD 
  public final static byte AD
Useful constant for GregorianCalendar.

o BC 
  public final static byte BC
Useful constant for GregorianCalendar.

Constructors

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

o 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 timezone.
o 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.
o 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 timezone.
aLocale - the given locale.
o 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.
o 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 HOUROFDAY time field in the calendar.
minute - the value used to set the MINUTE time field in the calendar.
o 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 HOUROFDAY 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.

Methods

o 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.
o 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.
o 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.
o computeFields 
  public void computeFields()
Overrides Calendar Converts UTC as milliseconds to time field values.

Overrides:
computeFields in class Calendar
o computeTime 
  protected void computeTime()
Overrides Calendar Converts time field values to UTC as milliseconds.

Overrides:
computeTime in class Calendar
o clone 
  public Object clone()
Overrides Cloneable

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

Overrides:
hashCode in class Object
o equals 
  public boolean equals(Object obj)
Overrides Calendar Compares the time field records. Equivalent to comparing result of conversion to UTC. Please see Calendar.equals for descriptions on parameters and the return value.

Overrides:
equals in class Calendar
o before 
  public boolean before(Object when)
Overrides Calendar Compares the time field records. Equivalent to comparing result of conversion to UTC. Please see Calendar.before for descriptions on parameters and the return value.

Overrides:
before in class Calendar
o after 
  public boolean after(Object when)
Overrides Calendar Compares the time field records. Equivalent to comparing result of conversion to UTC. Please see Calendar.after for descriptions on parameters and the return value.

Overrides:
after in class Calendar
o add 
  public void add(byte field,
                  int amount) throws IllegalArgumentException
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.
Overrides:
add in class Calendar
o roll 
  public void roll(byte field,
                   boolean up) throws IllegalArgumentException
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.
Overrides:
roll in class Calendar
o getMinimum 
  public int getMinimum(byte field)
Returns minimum value for the given field. e.g. for Gregorian DAYOFMONTH, 1 Please see Calendar.getMinimum for descriptions on parameters and the return value.

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

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

Overrides:
getLeastMaximum in class Calendar 
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