DateFormat is an abstract class for date/time formatting subclasses which
formats and parses dates or time in a language-independent manner.
The date/time formatting subclass, such as SimpleDateFormat, allows for
formatting (i.e., date -> text), parsing (text -> date), and
normalization. The date is represented as a
Date
object or
as the milliseconds since January 1, 1970, 00:00:00 GMT.
DateFormat provides many class methods for obtaining default date/time
formatters based on the default or a given loacle and a number of formatting
styles. The formatting styles include FULL, LONG, MEDIUM, and SHORT. More
detail and examples of using these styles are provided in the method
descriptions.
DateFormat helps you to format and parse dates for any locale.
Your code can be completely independent of the locale conventions for
months, days of the week, or even the calendar format: lunar vs. solar.
To format a date for the current Locale, use one of the
static factory methods:
myString = DateFormat.getDateInstance().format(myDate);
If you are formatting multiple numbers, it is
more efficient to get the format and use it multiple times so that
the system doesn't have to fetch the information about the local
language and country conventions multiple times.
DateFormat df = DateFormat.getDateInstance();
for (int i = 0; i <32a.length; ++i) {
output.println(df.format(myDate[i]) + "; ");
}
To format a number for a different Locale, specify it in the
call to getDateInstance().
DateFormat df = DateFormat.getDateInstance(DateFormat.LONG, Locale.FRANCE);
You can use a DateFormat to parse also.
myDate = df.parse(myString);
Use getDateInstance to get the normal date format for that country.
There are other static factory methods available.
Use getTimeInstance to get the time format for that country.
Use getDateTimeInstance to get a date and time format. You can pass in
different options to these factory methods to control the length of the
result; from SHORT to MEDIUM to LONG to FULL. The exact result depends
on the locale, but generally:
- SHORT is completely numeric, such as 12.13.52 or 3:30pm
- MEDIUM is longer, such as Jan 12, 1952
- LONG is longer, such as January 12, 1952 or 3:30:32pm
- FULL is pretty completely specified, such as
Tuesday, April 12, 1952 AD or 3:30:42pm PST.
You can also set the time zone on the format if you wish.
If you want even more control over the format or parsing,
(or want to give your users more control),
you can try casting the DateFormat you get from the factory methods
to a SimpleDateFormat. This will work for the majority
of countries; just remember to put it in a try block in case you
encounter an unusual one.
You can also use forms of the parse and format methods with
ParsePosition and FieldPosition to
allow you to
- progressively parse through pieces of a string.
- align any particular field, or find out where it is for selection
on the screen.
Synchronization
Date formats are not synchronized. It is recommended to create separate
format instances for each thread. If multiple threads access a format
concurrently, it must be synchronized externally.
AM_PM_FIELD
public static final int AM_PM_FIELD
FieldPosition selector for 'a' field alignment,
corresponding to the
Calendar.AM_PM
field.
DATE_FIELD
public static final int DATE_FIELD
FieldPosition selector for 'd' field alignment,
corresponding to the
Calendar.DATE
field.
DAY_OF_WEEK_FIELD
public static final int DAY_OF_WEEK_FIELD
DAY_OF_WEEK_IN_MONTH_FIELD
public static final int DAY_OF_WEEK_IN_MONTH_FIELD
DAY_OF_YEAR_FIELD
public static final int DAY_OF_YEAR_FIELD
DEFAULT
public static final int DEFAULT
Constant for default style pattern. Its value is MEDIUM.
DOW_LOCAL_FIELD
public static final int DOW_LOCAL_FIELD
FieldPosition selector for 'e' field alignment,
corresponding to the
Calendar.DOW_LOCAL
field.
ERA_FIELD
public static final int ERA_FIELD
FieldPosition selector for 'G' field alignment,
corresponding to the
Calendar.ERA
field.
EXTENDED_YEAR_FIELD
public static final int EXTENDED_YEAR_FIELD
FIELD_COUNT
public static final int FIELD_COUNT
Number of FieldPosition selectors for DateFormat.
Valid selectors range from 0 to FIELD_COUNT-1.
FRACTIONAL_SECOND_FIELD
public static final int FRACTIONAL_SECOND_FIELD
FULL
public static final int FULL
Constant for full style pattern.
HOUR0_FIELD
public static final int HOUR0_FIELD
FieldPosition selector for 'K' field alignment,
corresponding to the
Calendar.HOUR
field.
HOUR0_FIELD is used for the zero-based 12-hour clock.
For example, 11:30 PM + 1 hour results in 00:30 AM.
HOUR1_FIELD
public static final int HOUR1_FIELD
FieldPosition selector for 'h' field alignment,
corresponding to the
Calendar.HOUR
field.
HOUR1_FIELD is used for the one-based 12-hour clock.
For example, 11:30 PM + 1 hour results in 12:30 AM.
HOUR_OF_DAY0_FIELD
public static final int HOUR_OF_DAY0_FIELD
FieldPosition selector for 'H' field alignment,
corresponding to the
Calendar.HOUR_OF_DAY
field.
HOUR_OF_DAY0_FIELD is used for the zero-based 24-hour clock.
For example, 23:59 + 01:00 results in 00:59.
HOUR_OF_DAY1_FIELD
public static final int HOUR_OF_DAY1_FIELD
FieldPosition selector for 'k' field alignment,
corresponding to the
Calendar.HOUR_OF_DAY
field.
HOUR_OF_DAY1_FIELD is used for the one-based 24-hour clock.
For example, 23:59 + 01:00 results in 24:59.
JULIAN_DAY_FIELD
public static final int JULIAN_DAY_FIELD
FieldPosition selector for 'g' field alignment,
corresponding to the
Calendar.JULIAN_DAY
field.
LONG
public static final int LONG
Constant for long style pattern.
MEDIUM
public static final int MEDIUM
Constant for medium style pattern.
MILLISECONDS_IN_DAY_FIELD
public static final int MILLISECONDS_IN_DAY_FIELD
MILLISECOND_FIELD
public static final int MILLISECOND_FIELD
ICU 3.0 use FRACTIONAL_SECOND_FIELD.
Alias for FRACTIONAL_SECOND_FIELD.
MINUTE_FIELD
public static final int MINUTE_FIELD
FieldPosition selector for 'm' field alignment,
corresponding to the
Calendar.MINUTE
field.
MONTH_FIELD
public static final int MONTH_FIELD
FieldPosition selector for 'M' field alignment,
corresponding to the
Calendar.MONTH
field.
SECOND_FIELD
public static final int SECOND_FIELD
FieldPosition selector for 's' field alignment,
corresponding to the
Calendar.SECOND
field.
SHORT
public static final int SHORT
Constant for short style pattern.
STANDALONE_DAY_FIELD
public static final int STANDALONE_DAY_FIELD
FieldPosition selector for 'c' field alignment,
corresponding to the
Calendar.DAY_OF_WEEK
field.
This displays the stand alone day name, if available.
STANDALONE_MONTH_FIELD
public static final int STANDALONE_MONTH_FIELD
FieldPosition selector for 'L' field alignment,
corresponding to the
Calendar.MONTH
field.
This displays the stand alone month name, if available.
TIMEZONE_FIELD
public static final int TIMEZONE_FIELD
TIMEZONE_GENERIC_FIELD
public static final int TIMEZONE_GENERIC_FIELD
TIMEZONE_RFC_FIELD
public static final int TIMEZONE_RFC_FIELD
WEEK_OF_MONTH_FIELD
public static final int WEEK_OF_MONTH_FIELD
WEEK_OF_YEAR_FIELD
public static final int WEEK_OF_YEAR_FIELD
YEAR_FIELD
public static final int YEAR_FIELD
FieldPosition selector for 'y' field alignment,
corresponding to the
Calendar.YEAR
field.
YEAR_WOY_FIELD
public static final int YEAR_WOY_FIELD
FieldPosition selector for 'Y' field alignment,
corresponding to the
Calendar.YEAR_WOY
field.
calendar
protected Calendar calendar
The calendar that DateFormat
uses to produce the time field
values needed to implement date and time formatting. Subclasses should
initialize this to a calendar appropriate for the locale associated with
this DateFormat
.
numberFormat
protected NumberFormat numberFormat
The number formatter that DateFormat
uses to format numbers
in dates and times. Subclasses should initialize this to a number format
appropriate for the locale associated with this DateFormat
.
clone
public Object clone()
Overrides Cloneable
equals
public boolean equals(Object obj)
Overrides equals
format
public final String format(Date date)
Formats a Date into a date/time string.
date
- the time value to be formatted into a time string.
- the formatted time string.
format
public final StringBuffer format(Date date,
StringBuffer toAppendTo,
FieldPosition fieldPosition)
Formats a Date into a date/time string.
date
- a Date to be formatted into a date/time string.toAppendTo
- the string buffer for the returning date/time string.fieldPosition
- keeps track of the position of the field
within the returned string.
On input: an alignment field,
if desired. On output: the offsets of the alignment field. For
example, given a time text "1996.07.10 AD at 15:08:56 PDT",
if the given fieldPosition is DateFormat.YEAR_FIELD, the
begin index and end index of fieldPosition will be set to
0 and 4, respectively.
Notice that if the same time field appears
more than once in a pattern, the fieldPosition will be set for the first
occurence of that time field. For instance, formatting a Date to
the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
"h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
the begin index and end index of fieldPosition will be set to
5 and 8, respectively, for the first occurence of the timezone
pattern character 'z'.
- the formatted date/time string.
format
public final StringBuffer format(Object obj,
StringBuffer toAppendTo,
FieldPosition fieldPosition)
Overrides Format.
Formats a time object into a time string. Examples of time objects
are a time value expressed in milliseconds and a Date object.
obj
- must be a Number or a Date or a Calendar.toAppendTo
- the string buffer for the returning time string.fieldPosition
- keeps track of the position of the field
within the returned string.
On input: an alignment field,
if desired. On output: the offsets of the alignment field. For
example, given a time text "1996.07.10 AD at 15:08:56 PDT",
if the given fieldPosition is DateFormat.YEAR_FIELD, the
begin index and end index of fieldPosition will be set to
0 and 4, respectively.
Notice that if the same time field appears
more than once in a pattern, the fieldPosition will be set for the first
occurence of that time field. For instance, formatting a Date to
the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
"h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
the begin index and end index of fieldPosition will be set to
5 and 8, respectively, for the first occurence of the timezone
pattern character 'z'.
- the formatted time string.
format
public abstract StringBuffer format(Calendar cal,
StringBuffer toAppendTo,
FieldPosition fieldPosition)
Formats a date into a date/time string.
cal
- a Calendar set to the date and time to be formatted
into a date/time string.toAppendTo
- the string buffer for the returning date/time string.fieldPosition
- keeps track of the position of the field
within the returned string.
On input: an alignment field,
if desired. On output: the offsets of the alignment field. For
example, given a time text "1996.07.10 AD at 15:08:56 PDT",
if the given fieldPosition is DateFormat.YEAR_FIELD, the
begin index and end index of fieldPosition will be set to
0 and 4, respectively.
Notice that if the same time field appears
more than once in a pattern, the fieldPosition will be set for the first
occurence of that time field. For instance, formatting a Date to
the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
"h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
the begin index and end index of fieldPosition will be set to
5 and 8, respectively, for the first occurence of the timezone
pattern character 'z'.
- the formatted date/time string.
getAvailableLocales
public static Locale[] getAvailableLocales()
Gets the set of locales for which DateFormats are installed.
- the set of locales for which DateFormats are installed.
getAvailableULocales
public static ULocale[] getAvailableULocales()
Gets the set of locales for which DateFormats are installed.
- the set of locales for which DateFormats are installed.
getCalendar
public Calendar getCalendar()
Gets the calendar associated with this date/time formatter.
- the calendar associated with this date/time formatter.
getDateInstance
public static final DateFormat getDateInstance()
Gets the date formatter with the default formatting style
for the default locale.
getDateInstance
public static final DateFormat getDateInstance(Calendar cal,
int dateStyle)
Convenience overload
getDateInstance
public static final DateFormat getDateInstance(Calendar cal,
int dateStyle,
Locale locale)
Create a
DateFormat
object that can be used to format dates in
the calendar system specified by
cal
.
cal
- The calendar system for which a date format is desired.dateStyle
- The type of date format desired. This can be
SHORT
, MEDIUM
,
etc.locale
- The locale for which the date format is desired.
getDateInstance
public static final DateFormat getDateInstance(Calendar cal,
int dateStyle,
ULocale locale)
Create a
DateFormat
object that can be used to format dates in
the calendar system specified by
cal
.
cal
- The calendar system for which a date format is desired.dateStyle
- The type of date format desired. This can be
SHORT
, MEDIUM
,
etc.locale
- The locale for which the date format is desired.
getDateInstance
public static final DateFormat getDateInstance(int style)
Gets the date formatter with the given formatting style
for the default locale.
style
- the given formatting style. For example,
SHORT for "M/d/yy" in the US locale.
getDateInstance
public static final DateFormat getDateInstance(int style,
Locale aLocale)
Gets the date formatter with the given formatting style
for the given locale.
style
- the given formatting style. For example,
SHORT for "M/d/yy" in the US locale.aLocale
- the given locale.
getDateInstance
public static final DateFormat getDateInstance(int style,
ULocale locale)
Gets the date formatter with the given formatting style
for the given locale.
style
- the given formatting style. For example,
SHORT for "M/d/yy" in the US locale.locale
- the given ulocale.
getDateTimeInstance
public static final DateFormat getDateTimeInstance()
Gets the date/time formatter with the default formatting style
for the default locale.
getDateTimeInstance
public static final DateFormat getDateTimeInstance(Calendar cal,
int dateStyle,
int timeStyle)
Convenience overload
getDateTimeInstance
public static final DateFormat getDateTimeInstance(Calendar cal,
int dateStyle,
int timeStyle,
Locale locale)
Create a
DateFormat
object that can be used to format dates and times in
the calendar system specified by
cal
.
Note: When this functionality is moved into the core JDK, this method
will probably be replaced by a new overload of
DateFormat.getInstance
.
cal
- The calendar system for which a date/time format is desired.dateStyle
- The type of date format desired. This can be
SHORT
, MEDIUM
,
etc.timeStyle
- The type of time format desired. This can be
SHORT
, MEDIUM
,
etc.locale
- The locale for which the date/time format is desired.
DateFormat.getDateTimeInstance
getDateTimeInstance
public static final DateFormat getDateTimeInstance(Calendar cal,
int dateStyle,
int timeStyle,
ULocale locale)
Create a
DateFormat
object that can be used to format dates and times in
the calendar system specified by
cal
.
Note: When this functionality is moved into the core JDK, this method
will probably be replaced by a new overload of
DateFormat.getInstance
.
cal
- The calendar system for which a date/time format is desired.dateStyle
- The type of date format desired. This can be
SHORT
, MEDIUM
,
etc.timeStyle
- The type of time format desired. This can be
SHORT
, MEDIUM
,
etc.locale
- The locale for which the date/time format is desired.
DateFormat.getDateTimeInstance
getDateTimeInstance
public static final DateFormat getDateTimeInstance(int dateStyle,
int timeStyle)
Gets the date/time formatter with the given date and time
formatting styles for the default locale.
dateStyle
- the given date formatting style. For example,
SHORT for "M/d/yy" in the US locale.timeStyle
- the given time formatting style. For example,
SHORT for "h:mm a" in the US locale.
getDateTimeInstance
public static final DateFormat getDateTimeInstance(int dateStyle,
int timeStyle,
Locale aLocale)
Gets the date/time formatter with the given formatting styles
for the given locale.
dateStyle
- the given date formatting style.timeStyle
- the given time formatting style.aLocale
- the given locale.
getDateTimeInstance
public static final DateFormat getDateTimeInstance(int dateStyle,
int timeStyle,
ULocale locale)
Gets the date/time formatter with the given formatting styles
for the given locale.
dateStyle
- the given date formatting style.timeStyle
- the given time formatting style.locale
- the given ulocale.
getInstance
public static final DateFormat getInstance()
Get a default date/time formatter that uses the SHORT style for both the
date and the time.
getInstance
public static final DateFormat getInstance(Calendar cal,
Locale locale)
Convenience overload
getNumberFormat
public NumberFormat getNumberFormat()
Gets the number formatter which this date/time formatter uses to
format and parse a time.
- the number formatter which this date/time formatter uses.
getTimeInstance
public static final DateFormat getTimeInstance()
Gets the time formatter with the default formatting style
for the default locale.
getTimeInstance
public static final DateFormat getTimeInstance(Calendar cal,
int timeStyle)
Convenience overload
getTimeInstance
public static final DateFormat getTimeInstance(Calendar cal,
int timeStyle,
Locale locale)
Create a
DateFormat
object that can be used to format times in
the calendar system specified by
cal
.
Note: When this functionality is moved into the core JDK, this method
will probably be replaced by a new overload of
DateFormat.getInstance
.
cal
- The calendar system for which a time format is desired.timeStyle
- The type of time format desired. This can be
SHORT
, MEDIUM
,
etc.locale
- The locale for which the time format is desired.
DateFormat.getTimeInstance
getTimeInstance
public static final DateFormat getTimeInstance(Calendar cal,
int timeStyle,
ULocale locale)
Create a
DateFormat
object that can be used to format times in
the calendar system specified by
cal
.
Note: When this functionality is moved into the core JDK, this method
will probably be replaced by a new overload of
DateFormat.getInstance
.
cal
- The calendar system for which a time format is desired.timeStyle
- The type of time format desired. This can be
SHORT
, MEDIUM
,
etc.locale
- The locale for which the time format is desired.
DateFormat.getTimeInstance
getTimeInstance
public static final DateFormat getTimeInstance(int style)
Gets the time formatter with the given formatting style
for the default locale.
style
- the given formatting style. For example,
SHORT for "h:mm a" in the US locale.
getTimeInstance
public static final DateFormat getTimeInstance(int style,
Locale aLocale)
Gets the time formatter with the given formatting style
for the given locale.
style
- the given formatting style. For example,
SHORT for "h:mm a" in the US locale.aLocale
- the given locale.
getTimeInstance
public static final DateFormat getTimeInstance(int style,
ULocale locale)
Gets the time formatter with the given formatting style
for the given locale.
style
- the given formatting style. For example,
SHORT for "h:mm a" in the US locale.locale
- the given ulocale.
getTimeZone
public TimeZone getTimeZone()
Gets the time zone.
- the time zone associated with the calendar of DateFormat.
hashCode
public int hashCode()
Overrides hashCode
isLenient
public boolean isLenient()
Tell whether date/time parsing is to be lenient.
parse
public Date parse(String text)
throws ParseException
Parse a date/time string.
text
- The date/time string to be parsed
- A Date, or null if the input could not be parsed
parse
public final Date parse(String text,
ParsePosition pos)
Parse a date/time string according to the given parse position. For
example, a time text "07/10/96 4:5 PM, PDT" will be parsed into a Date
that is equivalent to Date(837039928046).
By default, parsing is lenient: If the input is not in the form used
by this object's format method but can still be parsed as a date, then
the parse succeeds. Clients may insist on strict adherence to the
format by calling setLenient(false).
text
- The date/time string to be parsedpos
- On input, the position at which to start parsing; on
output, the position at which parsing terminated, or the
start position if the parse failed.
- A Date, or null if the input could not be parsed
parse
public abstract void parse(String text,
Calendar cal,
ParsePosition pos)
Parse a date/time string according to the given parse position.
For example, a time text "07/10/96 4:5 PM, PDT" will be parsed
into a Calendar that is equivalent to Date(837039928046). The
caller should clear the calendar before calling this method,
unless existing field information is to be kept.
By default, parsing is lenient: If the input is not in the form used
by this object's format method but can still be parsed as a date, then
the parse succeeds. Clients may insist on strict adherence to the
format by calling setLenient(false).
text
- The date/time string to be parsedcal
- The calendar into which parsed data will be stored.
In general, this should be cleared before calling this
method. If this parse fails, the calendar may still
have been modified.pos
- On input, the position at which to start parsing; on
output, the position at which parsing terminated, or the
start position if the parse failed.
parseObject
public Object parseObject(String source,
ParsePosition pos)
Parse a date/time string into an Object. This convenience method simply
calls parse(String, ParsePosition).
setCalendar
public void setCalendar(Calendar newCalendar)
Set the calendar to be used by this date format. Initially, the default
calendar for the specified or default locale is used.
newCalendar
- the new Calendar to be used by the date format
setLenient
public void setLenient(boolean lenient)
Specify whether or not date/time parsing is to be lenient. With
lenient parsing, the parser may use heuristics to interpret inputs that
do not precisely match this object's format. With strict parsing,
inputs must match this object's format.
lenient
- when true, parsing is lenient
setNumberFormat
public void setNumberFormat(NumberFormat newNumberFormat)
Allows you to set the number formatter.
newNumberFormat
- the given new NumberFormat.
setTimeZone
public void setTimeZone(TimeZone zone)
Sets the time zone for the calendar of this DateFormat object.
zone
- the given new time zone.