com.sun.cldc.util.j2me
Class TimeZoneImpl

java.lang.Object
  java.util.TimeZone
      com.sun.cldc.util.TimeZoneImplementation
          com.sun.cldc.util.j2me.TimeZoneImpl

public class TimeZoneImpl
extends TimeZoneImplementation

This class provides the time zone implementations for J2ME CLDC/MIDP. By default, the only supported time zone is UTC/GMT. Vendor-specific implementations may provide additional time zones.

For Sun SPOTs the following additional time zones are supported:

     HST, AST, PST, MST, CST & EST and "GMT+hh:mm"
 

plus we allow other timezones to be user defined via system properties passed in to Squawk on the command line.

The default time zone is "PST". It can be changed to another supported time zone by setting the system property com.sun.cldc.util.j2me.TimeZoneImpl.timezone E.g. to make the default be "EST" include the following in the command line to start Squawk:

    -Dcom.sun.cldc.util.j2me.TimeZoneImpl.timezone=EST
 

To add additional time zones use the system property com.sun.cldc.util.j2me.TimeZoneImpl.additionaltimezones, where its value is a list of the time zones to add in the format:

     tzname1={+-}hh{:mm}{,daylight_savings_spec};tzname2=...;
 

where

     daylight_savings_spec =
           start_month,start_day,start_day_of_week,start_time,
           end_month,end_day,end_day_of_week,end_time,hh{:mm}
 

To specify the last Sunday of the month set the day_of_week to Calendar.SUNDAY and the day to -1, i.e. day is interpreted then to be which Sunday (1 = first, 2 = second, -2 = second last, etc.).

It is also possible to specify a date such as the first Sunday before/after a given day of the month by setting the day_of_week to be negative. If the day value is negative then the day_of_week before that day is specified.

For example an Australian might define:

    -Dcom.sun.cldc.util.j2me.TimeZoneImpl.additionaltimezones=
          Australia/Perth=8;Australia/Darwin=9:30;Australia/Adelaide=9:30,9,-1,1,2,2,-1,1,2,1;
          Australia/Brisbane=10;Australia/Sydney=10,9,-1,1,2,2,-1,1,3,1;
          Australia/Lord_Howe=10:30,9,-1,1,2,2,-1,1,3,0:30;
 

Refer to the time zone defining code at the end of this file for examples of the values to use, e.g.:

    new TimeZoneImpl((int)(9.5*ONE_HOUR), "Australia/Adelaide",
                Calendar.OCTOBER, -1, Calendar.SUNDAY, 2*ONE_HOUR,
                Calendar.MARCH, -1, Calendar.SUNDAY, 3*ONE_HOUR, 1*ONE_HOUR),
    // Rule AS  1987    max -   Oct lastSun 2:00s   1:00    -
    // Rule AS  1995    max -   Mar lastSun 2:00s   0   -
    // Australia/Adelaide   South Australia(AU) 9:30    AS  CST
 

See Also:

TimeZone

Field Summary

static String

HOME_ID

Constructor Summary

TimeZoneImpl()

Method Summary

boolean	equals(Object object) Indicates whether some other object is "equal to" this one.
String	getID() Gets the ID of this time zone.
String[]	getIDs() Gets all the available IDs supported.
TimeZone	getInstance(String ID) Gets the TimeZone for the given ID.
int	getOffset(int era, int year, int month, int day, int dayOfWeek, int millis) Gets the time zone offset, for the specified date, modified in case of daylight savings.
int	getRawOffset() Gets the GMT offset for this time zone.
int	hashCode() Returns a hash code value for the object.
boolean	useDaylightTime() Queries if this time zone uses Daylight Savings Time.

Methods inherited from class java.util.TimeZone

getAvailableIDs, getDefault, getTimeZone

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

HOME_ID

public static String HOME_ID

Constructor Detail

TimeZoneImpl

public TimeZoneImpl()

Method Detail

getOffset

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

Gets the time zone offset, for the specified date, modified in case of daylight savings. This is the offset to add *to* GMT to get local time. This method may return incorrect results for rules that start at the end of February (e.g., last Sunday in February) or the beginning of March (e.g., March 1).

Specified by:

getOffset in class TimeZone

Parameters:

era - The era of the given date (0 = BC, 1 = AD).

year - The year in the given date.

month - The month in the given date. Month is 0-based. e.g., 0 for January.

day - The day-in-month of the given date.

dayOfWeek - The day-of-week of the given date.

millis - The milliseconds in day in standard local time.

Returns:

The offset to add *to* GMT to get local time.

Throws:

IllegalArgumentException - the era, month, day, dayOfWeek, or millis parameters are out of range

getRawOffset

public int getRawOffset()

Gets the GMT offset for this time zone.

Specified by:

getRawOffset in class TimeZone

Returns:

the GMT offset for this time zone.

useDaylightTime

public boolean useDaylightTime()

Queries if this time zone uses Daylight Savings Time.

Specified by:

useDaylightTime in class TimeZone

Returns:

if this time zone uses Daylight Savings Time.

getID

public String getID()

Gets the ID of this time zone.

Overrides:

getID in class TimeZone

Returns:

the ID of this time zone.

getInstance

public TimeZone getInstance(String ID)

Gets the TimeZone for the given ID.

Specified by:

getInstance in class TimeZoneImplementation

Parameters:

ID - the ID for a TimeZone, either an abbreviation such as "GMT", or a full name such as "America/Los_Angeles".

The only time zone ID that is required to be supported is "GMT", though typically, the timezones for the regions where the device is sold should be supported.

Returns:

the specified TimeZone, or null if the given ID cannot be understood.

getIDs

public String[] getIDs()

Gets all the available IDs supported.

Specified by:

getIDs in class TimeZoneImplementation

Returns:

an array of IDs.

equals

public boolean equals(Object object)

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

Overrides:

equals in class Object

Parameters:

object - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

See Also:

hashCode(), Hashtable

hashCode

public int hashCode()

Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java^TM programming language.)

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), Hashtable