public abstract class DateFormat extends Format
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 locale 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 dates, 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 < myDate.length; ++i) { output.println(df.format(myDate[i]) + "; "); }
To format a date 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
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.
Format
,
NumberFormat
,
SimpleDateFormat
,
Calendar
,
GregorianCalendar
,
TimeZone
,
Serialized FormModifier and Type | Class and Description |
---|---|
static class |
DateFormat.Field
Defines constants that are used as attribute keys in the
AttributedCharacterIterator returned
from DateFormat.formatToCharacterIterator and as
field identifiers in FieldPosition . |
Modifier and Type | Field and Description |
---|---|
static int |
AM_PM_FIELD
Useful constant for AM_PM field alignment.
|
protected Calendar |
calendar
The
Calendar instance used for calculating the date-time fields
and the instant of time. |
static int |
DATE_FIELD
Useful constant for DATE field alignment.
|
static int |
DAY_OF_WEEK_FIELD
Useful constant for DAY_OF_WEEK field alignment.
|
static int |
DAY_OF_WEEK_IN_MONTH_FIELD
Useful constant for DAY_OF_WEEK_IN_MONTH field alignment.
|
static int |
DAY_OF_YEAR_FIELD
Useful constant for DAY_OF_YEAR field alignment.
|
static int |
DEFAULT
Constant for default style pattern.
|
static int |
ERA_FIELD
Useful constant for ERA field alignment.
|
static int |
FULL
Constant for full style pattern.
|
static int |
HOUR_OF_DAY0_FIELD
Useful constant for zero-based HOUR_OF_DAY field alignment.
|
static int |
HOUR_OF_DAY1_FIELD
Useful constant for one-based HOUR_OF_DAY field alignment.
|
static int |
HOUR0_FIELD
Useful constant for zero-based HOUR field alignment.
|
static int |
HOUR1_FIELD
Useful constant for one-based HOUR field alignment.
|
static int |
LONG
Constant for long style pattern.
|
static int |
MEDIUM
Constant for medium style pattern.
|
static int |
MILLISECOND_FIELD
Useful constant for MILLISECOND field alignment.
|
static int |
MINUTE_FIELD
Useful constant for MINUTE field alignment.
|
static int |
MONTH_FIELD
Useful constant for MONTH field alignment.
|
protected NumberFormat |
numberFormat
The number formatter that
DateFormat uses to format numbers
in dates and times. |
static int |
SECOND_FIELD
Useful constant for SECOND field alignment.
|
static int |
SHORT
Constant for short style pattern.
|
static int |
TIMEZONE_FIELD
Useful constant for TIMEZONE field alignment.
|
static int |
WEEK_OF_MONTH_FIELD
Useful constant for WEEK_OF_MONTH field alignment.
|
static int |
WEEK_OF_YEAR_FIELD
Useful constant for WEEK_OF_YEAR field alignment.
|
static int |
YEAR_FIELD
Useful constant for YEAR field alignment.
|
Modifier | Constructor and Description |
---|---|
protected |
DateFormat()
Create a new date format.
|
Modifier and Type | Method and Description |
---|---|
Object |
clone()
Overrides Cloneable
|
boolean |
equals(Object obj)
Overrides equals
|
String |
format(Date date)
Formats a Date into a date/time string.
|
abstract StringBuffer |
format(Date date,
StringBuffer toAppendTo,
FieldPosition fieldPosition)
Formats a Date into a date/time string.
|
StringBuffer |
format(Object obj,
StringBuffer toAppendTo,
FieldPosition fieldPosition)
Overrides Format.
|
static Locale[] |
getAvailableLocales()
Returns an array of all locales for which the
get*Instance methods of this class can return
localized instances. |
Calendar |
getCalendar()
Gets the calendar associated with this date/time formatter.
|
static DateFormat |
getDateInstance()
Gets the date formatter with the default formatting style
for the default locale.
|
static DateFormat |
getDateInstance(int style)
Gets the date formatter with the given formatting style
for the default locale.
|
static DateFormat |
getDateInstance(int style,
Locale aLocale)
Gets the date formatter with the given formatting style
for the given locale.
|
static DateFormat |
getDateTimeInstance()
Gets the date/time formatter with the default formatting style
for the default locale.
|
static DateFormat |
getDateTimeInstance(int dateStyle,
int timeStyle)
Gets the date/time formatter with the given date and time
formatting styles for the default locale.
|
static DateFormat |
getDateTimeInstance(int dateStyle,
int timeStyle,
Locale aLocale)
Gets the date/time formatter with the given formatting styles
for the given locale.
|
static DateFormat |
getInstance()
Get a default date/time formatter that uses the SHORT style for both the
date and the time.
|
NumberFormat |
getNumberFormat()
Gets the number formatter which this date/time formatter uses to
format and parse a time.
|
static DateFormat |
getTimeInstance()
Gets the time formatter with the default formatting style
for the default locale.
|
static DateFormat |
getTimeInstance(int style)
Gets the time formatter with the given formatting style
for the default locale.
|
static DateFormat |
getTimeInstance(int style,
Locale aLocale)
Gets the time formatter with the given formatting style
for the given locale.
|
TimeZone |
getTimeZone()
Gets the time zone.
|
int |
hashCode()
Overrides hashCode
|
boolean |
isLenient()
Tell whether date/time parsing is to be lenient.
|
Date |
parse(String source)
Parses text from the beginning of the given string to produce a date.
|
abstract Date |
parse(String source,
ParsePosition pos)
Parse a date/time string according to the given parse position.
|
Object |
parseObject(String source,
ParsePosition pos)
Parses text from a string to produce a
Date . |
void |
setCalendar(Calendar newCalendar)
Set the calendar to be used by this date format.
|
void |
setLenient(boolean lenient)
Specify whether or not date/time parsing is to be lenient.
|
void |
setNumberFormat(NumberFormat newNumberFormat)
Allows you to set the number formatter.
|
void |
setTimeZone(TimeZone zone)
Sets the time zone for the calendar of this
DateFormat object. |
format, formatToCharacterIterator, parseObject
protected Calendar calendar
protected NumberFormat numberFormat
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
.public static final int ERA_FIELD
public static final int YEAR_FIELD
public static final int MONTH_FIELD
public static final int DATE_FIELD
public static final int HOUR_OF_DAY1_FIELD
public static final int HOUR_OF_DAY0_FIELD
public static final int MINUTE_FIELD
public static final int SECOND_FIELD
public static final int MILLISECOND_FIELD
public static final int DAY_OF_WEEK_FIELD
public static final int DAY_OF_YEAR_FIELD
public static final int DAY_OF_WEEK_IN_MONTH_FIELD
public static final int WEEK_OF_YEAR_FIELD
public static final int WEEK_OF_MONTH_FIELD
public static final int AM_PM_FIELD
public static final int HOUR1_FIELD
public static final int HOUR0_FIELD
public static final int TIMEZONE_FIELD
public static final int FULL
public static final int LONG
public static final int MEDIUM
public static final int SHORT
public static final int DEFAULT
public final StringBuffer format(Object obj, StringBuffer toAppendTo, FieldPosition fieldPosition)
format
in class Format
obj
- must be a Number or a Date.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
occurrence 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 occurrence of the timezone
pattern character 'z'.Format
public abstract StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition)
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
occurrence 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 occurrence of the timezone
pattern character 'z'.public final String format(Date date)
date
- the time value to be formatted into a time string.public Date parse(String source) throws ParseException
See the parse(String, ParsePosition)
method for more information
on date parsing.
source
- A String
whose beginning should be parsed.Date
parsed from the string.ParseException
- if the beginning of the specified string
cannot be parsed.public abstract Date parse(String source, ParsePosition pos)
"07/10/96 4:5 PM, PDT"
will be parsed into a Date
that is equivalent to Date(837039900000L)
.
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)
.
This parsing operation uses the calendar
to produce
a Date
. As a result, the calendar
's date-time
fields and the TimeZone
value may have been
overwritten, depending on subclass implementations. Any TimeZone
value that has previously been set by a call to
setTimeZone
may need
to be restored for further operations.
source
- 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.Date
, or null
if the input could not be parsedpublic Object parseObject(String source, ParsePosition pos)
Date
.
The method attempts to parse text starting at the index given by
pos
.
If parsing succeeds, then the index of pos
is updated
to the index after the last character used (parsing does not necessarily
use all characters up to the end of the string), and the parsed
date is returned. The updated pos
can be used to
indicate the starting point for the next call to this method.
If an error occurs, then the index of pos
is not
changed, the error index of pos
is set to the index of
the character where the error occurred, and null is returned.
See the parse(String, ParsePosition)
method for more information
on date parsing.
parseObject
in class Format
source
- A String
, part of which should be parsed.pos
- A ParsePosition
object with index and error
index information as described above.Date
parsed from the string. In case of
error, returns null.NullPointerException
- if pos
is null.public static final DateFormat getTimeInstance()
public static final DateFormat getTimeInstance(int style)
style
- the given formatting style. For example,
SHORT for "h:mm a" in the US locale.public static final DateFormat getTimeInstance(int style, Locale aLocale)
style
- the given formatting style. For example,
SHORT for "h:mm a" in the US locale.aLocale
- the given locale.public static final DateFormat getDateInstance()
public static final DateFormat getDateInstance(int style)
style
- the given formatting style. For example,
SHORT for "M/d/yy" in the US locale.public static final DateFormat getDateInstance(int style, Locale aLocale)
style
- the given formatting style. For example,
SHORT for "M/d/yy" in the US locale.aLocale
- the given locale.public static final DateFormat getDateTimeInstance()
public static final DateFormat getDateTimeInstance(int dateStyle, int timeStyle)
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.public static final DateFormat getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale)
dateStyle
- the given date formatting style.timeStyle
- the given time formatting style.aLocale
- the given locale.public static final DateFormat getInstance()
public static Locale[] getAvailableLocales()
get*Instance
methods of this class can return
localized instances.
The returned array represents the union of locales supported by the Java
runtime and by installed
DateFormatProvider
implementations.
It must contain at least a Locale
instance equal to
Locale.US
.DateFormat
instances are available.public void setCalendar(Calendar newCalendar)
Any TimeZone
and leniency values that have previously been set are
overwritten by newCalendar
's values.
newCalendar
- the new Calendar
to be used by the date formatpublic Calendar getCalendar()
public void setNumberFormat(NumberFormat newNumberFormat)
newNumberFormat
- the given new NumberFormat.public NumberFormat getNumberFormat()
public void setTimeZone(TimeZone zone)
DateFormat
object.
This method is equivalent to the following call.
getCalendar().setTimeZone(zone)
The TimeZone
set by this method is overwritten by a
setCalendar
call.
The TimeZone
set by this method may be overwritten as
a result of a call to the parse method.
zone
- the given new time zone.public TimeZone getTimeZone()
getCalendar().getTimeZone()
public void setLenient(boolean lenient)
This method is equivalent to the following call.
getCalendar().setLenient(lenient)
This leniency value is overwritten by a call to setCalendar()
.
lenient
- when true
, parsing is lenientCalendar.setLenient(boolean)
public boolean isLenient()
getCalendar().isLenient()
true
if the calendar
is lenient;
false
otherwise.Calendar.isLenient()
public int hashCode()
hashCode
in class Object
Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
public boolean equals(Object obj)
equals
in class Object
obj
- the reference object with which to compare.true
if this object is the same as the obj
argument; false
otherwise.Object.hashCode()
,
HashMap
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