Chapter 17
The java.util Package

SimpleTimeZone

Name

SimpleTimeZone

Synopsis

Class Name:

java.util.SimpleTimeZone

Superclass:

java.util.TimeZone

Immediate Subclasses:

None

Interfaces Implemented:

None

Availability:

New as of JDK 1.1

The SimpleTimeZone class is a concrete subclass of the abstract TimeZone class. SimpleTimeZone represents a time zone offset for use with GregorianCalendar. SimpleTimeZone does not take into account the historical vicissitudes of daylight savings time, however. Instead, it assumes that the shifts to and from daylight savings time always occur at the same time of the year.

Normally, SimpleTimeZone objects are not created directly, but instead obtained by calling TimeZone.getDefault(). This method creates a subclass of TimeZone that is appropriate for the current locale. You can also call TimeZone.getTimeZone() to obtain a TimeZone object for a specific time zone.

Class Summary

public class java.util.SimpleTimeZone extends java.util.TimeZone {
  // Constructors
  public SimpleTimeZone(int rawOffset, String ID);
  public SimpleTimeZone(int rawOffset, String ID, int startMonth, 
                       int startDayOfWeekInMonth, int startDayOfWeek, 
                       int startTime, int endMonth, int endDayOfWeekInMonth,
                       int endDayOfWeek, int endTime);
  // Instance Methods
  public Object clone();
  public boolean equals(Object obj); 
  public int getOffset(int era, int year, int month, int day, 
                      int dayOfWeek, int millis); 
  public int getRawOffset();
  public synchronized int hashCode();
  public boolean inDaylightTime(Date date); 
  public void setEndRule(int month, int dayOfWeekInMonth, 
                        int dayOfWeek, int time);
  public void setRawOffset(int offsetMillis); 
  public void setStartRule(int month, int dayOfWeekInMonth, 
                          int dayOfWeek, int time);
  public void setStartYear(int year);
  public boolean useDaylightTime();
}

Constructors

SimpleTimeZone

public SimpleTimeZone(int rawOffset, String ID)

Parameters

rawOffset

The raw offset of this time zone from GMT, in milliseconds.

ID

The ID of this time zone.

Description

This constructor creates a SimpleTimeZone that uses the given offset from GMT and has the specified ID. This constructor creates a SimpleTimeZone that does not use daylight savings time.

 public SimpleTimeZone(int rawOffset, String ID, int startMonth, int startDayOfWeekInMonth, int startDayOfWeek, int startTime, int endMonth, int endDayOfWeekInMonth, int endDayOfWeek, int endTime)

Parameters

rawOffset

The raw offset of this time zone from GMT, in milliseconds.

ID

The ID of this time zone.

startMonth

The month when daylight savings time begins.

startDayOfWeekInMonth

The week in the month when daylight savings time begins.

startDayOfWeek

The day of the week when daylight savings time begins.

startTime

The time of day when daylight savings time begins, in milliseconds.

endMonth

The month when daylight savings time ends.

endDayOfWeekInMonth

The week in the month when daylight savings time ends.

endDayOfWeek

The day of the week when daylight savings time ends.

endTime

The time of day when daylight savings time ends, in milliseconds.

Description

This constructor creates a SimpleTimeZone that uses the given offset from GMT, has the specified ID, and uses daylight savings time. Daylight savings time begins and ends at the specified dates and times.

For example, Brazil Eastern Time (BET) is three hours behind GMT. Daylight savings time for BET starts on the first Sunday in April at 2:00 AM, and ends on the last Sunday in October, also at 2:00 A.M. To construct a TimeZone that represents BET, you would use the following:

new SimpleTimeZone(-3 * 60 * 60 * 1000, "BET",
                  Calendar.APRIL, 1, 
                  Calendar.SUNDAY, 2 * 60 * 60 * 1000,
                  Calendar.OCTOBER, -1,
                  Calendar.SUNDAY, 2 * 60 * 60 * 1000)

Instance Methods

clone

public Object clone()

Returns

A copy of this SimpleTimeZone.

Overrides

TimeZone.clone()

Description

This method creates a copy of this SimpleTimeZone and returns it.

equals

public boolean equals(Object obj)

Parameters

obj: The object to be compared with this object.

Returns

true if the objects are equal; false if they are not.

Overrides

Object.equals()

Description

This method returns true if obj is an instance of SimpleTimeZone, and it contains the same value as the object this method is associated with.

getOffset

 public int getOffset(int era, int year, int month, int day, int dayOfWeek, int millis)

Parameters

era

The era.

year

The year.

month

The month.

day

The day.

dayOfWeek

The day of the week.

millis

The time of day in milliseconds.

Returns

An offset from GMT, in milliseconds.

Overrides

TimeZone.getOffset()

Description

This method calculates an offset from GMT for the given date for this SimpleTimeZone. In other words, the offset takes daylight savings time into account. The return value should be added to GMT to get local time.

getRawOffset

public int getRawOffset()

Returns

An offset from GMT, in milliseconds.

Overrides

TimeZone.getRawOffset()

Description

This method returns the raw offset from GMT for this SimpleTimeZone. In other words, the offset does not take daylight savings time into account.

hashCode

public synchronized int hashCode()

Returns

A hashcode for this SimpleTimeZone.

Overrides

Object.hashCode()

Description

This method returns a hashcode for this object.

inDaylightTime

public boolean inDaylightTime(Date date)

Parameters

date: The date to be tested.

Returns

true if the given date is between the start and end of daylight savings time for this SimpleTimeZone; false otherwise.

Overrides

TimeZone.inDaylightTime()

Description

This method returns a boolean value that indicates if the given date is in daylight savings time for this SimpleTimeZone.

setEndRule

 public void setEndRule(int month, int dayOfWeekInMonth, int dayOfWeek, int time)

Parameters

month

The month when daylight savings time ends.

DayOfWeekInMonth

The week of the month when daylight savings time ends.

dayOfWeek

The day of the week when daylight savings time ends.

time

The time of day when daylight savings time ends, in milliseconds.

Description

This method sets the time when daylight savings time ends for this SimpleTimeZone. For example, to set the end of daylight savings time to 2 A.M. on the last Sunday in October, you would use the following:

setEndRule(Calendar.OCTOBER, -1, Calendar.SUNDAY, 
           2 * 60 * 60 * 1000)

setRawOffset

public void setRawOffset(int offsetMillis)

Parameters

offsetMillis: The new raw offset from GMT, in milliseconds.

Overrides

TimeZone.setRawOffset()

Description

This method is used to set the raw offset value for this SimpleTimeZone.

setStartRule

 public void setStartRule(int month, int dayOfWeekInMonth, int dayOfWeek, int time)

Parameters

month

The month when daylight savings time begins.

DayOfWeekInMonth

The week of the month when daylight savings time begins.

dayOfWeek

The day of the week when daylight savings time begins.

time

The time of day when daylight savings time begins, in milliseconds.

Description

This method sets the time when daylight savings time begins for this SimpleTimeZone. For example, to set the beginning of daylight savings time to 2 A.M. on the first Sunday in April, you would use the following:

setEndRule(Calendar.APRIL, 1, Calendar.SUNDAY, 
           2 * 60 * 60 * 1000)

setStartYear

public void setStartYear(int year)

Parameters

year: The year when daylight savings time begins.

Description

This method sets the year after which the start and end rules for daylight savings time are observed.

useDaylightTime

public boolean useDaylightTime()

Returns

true if this SimpleTimeZone uses daylight savings time; false otherwise.

Overrides

TimeZone.useDaylightTime()

Description

This method returns a boolean value that indicates whether or not this SimpleTimeZone uses daylight savings time.

Inherited Methods

Method	Inherited From	Method	Inherited From
`finalize()`	`Object`	`getClass()`	`Object`
`getID()`	`TimeZone`	`notify()`	`Object`
`notifyAll()`	`Object`	`setID()`	`TimeZone`
`toString()`	`Object`	`wait()`	`Object`
`wait(long)`	`Object`	`wait(long, int)`	`Object`