Class DateFormat
- All Implemented Interfaces:
 - 
Serializable,Cloneable 
- Direct Known Subclasses:
 SimpleDateFormat
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);
If the specified locale contains "ca" (calendar), "rg" (region override), and/or "tz" (timezone) Unicode extensions, the calendar, the country and/or the time zone for formatting are overridden. If both "ca" and "rg" are specified, the calendar from the "ca" extension supersedes the implicit one from the "rg" extension.
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: 
- 
SHORTis completely numeric, such as12.13.52or3:30pm - 
MEDIUMis longer, such asJan 12, 1952 - 
LONGis longer, such asJanuary 12, 1952or3:30:32pm - 
FULLis pretty completely specified, such asTuesday, 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.
- API Note:
 - Consider using 
DateTimeFormatteras an immutable and thread-safe alternative. - Implementation Requirements:
 - The 
format(Date, StringBuffer, FieldPosition)andparse(String, ParsePosition)methods may throwNullPointerException, if any of their parameter isnull. The subclass may provide its own implementation and specification aboutNullPointerException. - The 
setCalendar(Calendar),setNumberFormat(NumberFormat)andsetTimeZone(TimeZone)methods do not throwNullPointerExceptionwhen their parameter isnull, but any subsequent operations on the same instance may throwNullPointerException. - The 
getCalendar(),getNumberFormat()andgetTimeZone()methods may returnnull, if the respective values of this instance is set tonullthrough the corresponding setter methods. For Example:getTimeZone()may returnnull, if theTimeZonevalue of this instance is set assetTimeZone(null). 
- The 
 - Since:
 - 1.1
 - See Also:
 
Nested Class Summary
| Modifier and Type | Class | 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. | 
Field Summary
| Modifier and Type | Field | Description | 
|---|---|---|
static final 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 final int | 
DATE_FIELD | 
  Useful constant for DATE field alignment.   | 
static final int | 
DAY_OF_WEEK_FIELD | 
  Useful constant for DAY_OF_WEEK field alignment.   | 
static final int | 
DAY_OF_WEEK_IN_MONTH_FIELD | 
  Useful constant for DAY_OF_WEEK_IN_MONTH field alignment.   | 
static final int | 
DAY_OF_YEAR_FIELD | 
  Useful constant for DAY_OF_YEAR field alignment.   | 
static final int | 
DEFAULT | 
  Constant for default style pattern.   | 
static final int | 
ERA_FIELD | 
  Useful constant for ERA field alignment.   | 
static final int | 
FULL | 
  Constant for full style pattern.   | 
static final int | 
HOUR_OF_DAY0_FIELD | 
  Useful constant for zero-based HOUR_OF_DAY field alignment.   | 
static final int | 
HOUR_OF_DAY1_FIELD | 
  Useful constant for one-based HOUR_OF_DAY field alignment.   | 
static final int | 
HOUR0_FIELD | 
  Useful constant for zero-based HOUR field alignment.   | 
static final int | 
HOUR1_FIELD | 
  Useful constant for one-based HOUR field alignment.   | 
static final int | 
LONG | 
  Constant for long style pattern.   | 
static final int | 
MEDIUM | 
  Constant for medium style pattern.   | 
static final int | 
MILLISECOND_FIELD | 
  Useful constant for MILLISECOND field alignment.   | 
static final int | 
MINUTE_FIELD | 
  Useful constant for MINUTE field alignment.   | 
static final 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 final int | 
SECOND_FIELD | 
  Useful constant for SECOND field alignment.   | 
static final int | 
SHORT | 
  Constant for short style pattern.   | 
static final int | 
TIMEZONE_FIELD | 
  Useful constant for TIMEZONE field alignment.   | 
static final int | 
WEEK_OF_MONTH_FIELD | 
  Useful constant for WEEK_OF_MONTH field alignment.   | 
static final int | 
WEEK_OF_YEAR_FIELD | 
  Useful constant for WEEK_OF_YEAR field alignment.   | 
static final int | 
YEAR_FIELD | 
  Useful constant for YEAR field alignment.   | 
Constructor Summary
| Modifier | Constructor | Description | 
|---|---|---|
protected  | 
  Create a new date format.   | 
Method Summary
| Modifier and Type | Method | Description | 
|---|---|---|
Object | 
clone() | 
  Overrides Cloneable   | 
boolean | 
equals | 
  Overrides equals   | 
final StringBuffer | 
format | 
  Formats the given   Object into a date-time string. | 
final String | 
format | 
  Formats a   Date into a date-time string. | 
abstract StringBuffer | 
format | 
  Formats a   Date into a date-time string. | 
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 final DateFormat | 
getDateInstance() | 
  Gets the date formatter with the default formatting style for the default   FORMAT locale. | 
static final DateFormat | 
getDateInstance | 
  Gets the date formatter with the given formatting style for the default   FORMAT locale. | 
static final DateFormat | 
getDateInstance | 
  Gets the date formatter with the given formatting style for the given locale.   | 
static final DateFormat | 
getDateTimeInstance() | 
  Gets the date/time formatter with the default formatting style for the default   FORMAT locale. | 
static final DateFormat | 
getDateTimeInstance | 
  Gets the date/time formatter with the given date and time formatting styles for the default   FORMAT locale. | 
static final DateFormat | 
getDateTimeInstance | 
  Gets the date/time formatter with the given formatting styles for the given locale.   | 
static final 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 final DateFormat | 
getTimeInstance() | 
  Gets the time formatter with the default formatting style for the default   FORMAT locale. | 
static final DateFormat | 
getTimeInstance | 
  Gets the time formatter with the given formatting style for the default   FORMAT locale. | 
static final DateFormat | 
getTimeInstance | 
  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 | 
  Parses text from the beginning of the given string to produce a date.   | 
abstract Date | 
parse | 
  Parse a date/time string according to the given parse position.   | 
Object | 
parseObject | 
  Parses text from a string to produce a   Date. | 
void | 
setCalendar | 
  Set the calendar to be used by this date format.   | 
void | 
setLenient | 
  Specify whether or not date/time parsing is to be lenient.   | 
void | 
setNumberFormat | 
  Allows you to set the number formatter.   | 
void | 
setTimeZone | 
  Sets the time zone for the calendar of this   DateFormat object. | 
Methods declared in class java.text.Format
format, formatToCharacterIterator, parseObject
Field Details
calendar
protected Calendar calendar
numberFormat
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.ERA_FIELD
public static final int ERA_FIELD
- See Also:
 
YEAR_FIELD
public static final int YEAR_FIELD
- See Also:
 
MONTH_FIELD
public static final int MONTH_FIELD
- See Also:
 
DATE_FIELD
public static final int DATE_FIELD
- See Also:
 
HOUR_OF_DAY1_FIELD
public static final int HOUR_OF_DAY1_FIELD
- See Also:
 
HOUR_OF_DAY0_FIELD
public static final int HOUR_OF_DAY0_FIELD
- See Also:
 
MINUTE_FIELD
public static final int MINUTE_FIELD
- See Also:
 
SECOND_FIELD
public static final int SECOND_FIELD
- See Also:
 
MILLISECOND_FIELD
public static final int MILLISECOND_FIELD
- See Also:
 
DAY_OF_WEEK_FIELD
public static final int DAY_OF_WEEK_FIELD
- See Also:
 
DAY_OF_YEAR_FIELD
public static final int DAY_OF_YEAR_FIELD
- See Also:
 
DAY_OF_WEEK_IN_MONTH_FIELD
public static final int DAY_OF_WEEK_IN_MONTH_FIELD
- See Also:
 
WEEK_OF_YEAR_FIELD
public static final int WEEK_OF_YEAR_FIELD
- See Also:
 
WEEK_OF_MONTH_FIELD
public static final int WEEK_OF_MONTH_FIELD
- See Also:
 
AM_PM_FIELD
public static final int AM_PM_FIELD
- See Also:
 
HOUR1_FIELD
public static final int HOUR1_FIELD
- See Also:
 
HOUR0_FIELD
public static final int HOUR0_FIELD
- See Also:
 
TIMEZONE_FIELD
public static final int TIMEZONE_FIELD
- See Also:
 
FULL
public static final int FULL
- See Also:
 
LONG
public static final int LONG
- See Also:
 
MEDIUM
public static final int MEDIUM
- See Also:
 
SHORT
public static final int SHORT
- See Also:
 
DEFAULT
public static final int DEFAULT
- See Also:
 
Constructor Details
DateFormat
protected DateFormat()
Method Details
format
public final StringBuffer format(Object obj, StringBuffer toAppendTo, FieldPosition fieldPosition)
Object into a date-time string. The formatted string is appended to the given StringBuffer.- Specified by:
 - 
formatin classFormat - Parameters:
 - 
obj- Must be aDateor aNumberrepresenting a millisecond offset from the Epoch. - 
toAppendTo- The string buffer for the returning date-time string. - 
fieldPosition- keeps track on the position of the field within the returned string. For example, given a date-time text"1996.07.10 AD at 15:08:56 PDT", if the givenfieldPositionisYEAR_FIELD, the begin index and end index offieldPositionwill be set to 0 and 4, respectively. Notice that if the same date-time field appears more than once in a pattern, thefieldPositionwill be set for the first occurrence of that date-time field. For instance, formatting aDateto the date-time string"1 PM PDT (Pacific Daylight Time)"using the pattern"h a z (zzzz)"and the alignment fieldTIMEZONE_FIELD, the begin index and end index offieldPositionwill be set to 5 and 8, respectively, for the first occurrence of the timezone pattern character'z'. - Returns:
 - the string buffer passed in as 
toAppendTo, with formatted text appended. - Throws:
 - 
IllegalArgumentException- if theFormatcannot format the givenobj. - See Also:
 
format
public abstract StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition)
Date into a date-time string. The formatted string is appended to the given StringBuffer.- Parameters:
 - 
date- a Date to be formatted into a date-time string. - 
toAppendTo- the string buffer for the returning date-time string. - 
fieldPosition- keeps track on the position of the field within the returned string. For example, given a date-time text"1996.07.10 AD at 15:08:56 PDT", if the givenfieldPositionisYEAR_FIELD, the begin index and end index offieldPositionwill be set to 0 and 4, respectively. Notice that if the same date-time field appears more than once in a pattern, thefieldPositionwill be set for the first occurrence of that date-time field. For instance, formatting aDateto the date-time string"1 PM PDT (Pacific Daylight Time)"using the pattern"h a z (zzzz)"and the alignment fieldTIMEZONE_FIELD, the begin index and end index offieldPositionwill be set to 5 and 8, respectively, for the first occurrence of the timezone pattern character'z'. - Returns:
 - the string buffer passed in as 
toAppendTo, with formatted text appended. 
format
public final String format(Date date)
Date into a date-time string.- Parameters:
 - 
date- the time value to be formatted into a date-time string. - Returns:
 - the formatted date-time string.
 
parse
public Date parse(String source) throws ParseException
 See the parse(String, ParsePosition) method for more information on date parsing.
- Parameters:
 - 
source- AStringwhose beginning should be parsed. - Returns:
 - A 
Dateparsed from the string. - Throws:
 - 
ParseException- if the beginning of the specified string cannot be parsed. 
parse
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.
- Parameters:
 - 
source- The date/time string to be parsed - 
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. - Returns:
 - A 
Date, ornullif the input could not be parsed 
parseObject
public 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.
- Specified by:
 - 
parseObjectin classFormat - Parameters:
 - 
source- AString, part of which should be parsed. - 
pos- AParsePositionobject with index and error index information as described above. - Returns:
 - A 
Dateparsed from the string. In case of error, returns null. - Throws:
 - 
NullPointerException- ifsourceorposis null. 
getTimeInstance
public static final DateFormat getTimeInstance()
FORMAT locale. This is equivalent to calling getTimeInstance(DEFAULT,
     Locale.getDefault(Locale.Category.FORMAT)).
- Returns:
 - a time formatter.
 - See Also:
 
getTimeInstance
public static final DateFormat getTimeInstance(int style)
FORMAT locale. This is equivalent to calling getTimeInstance(style,
     Locale.getDefault(Locale.Category.FORMAT)).
- Parameters:
 - 
style- the given formatting style. For example, SHORT for "h:mm a" in the US locale. - Returns:
 - a time formatter.
 - See Also:
 
getTimeInstance
public static final DateFormat getTimeInstance(int style, Locale aLocale)
- Parameters:
 - 
style- the given formatting style. For example, SHORT for "h:mm a" in the US locale. - 
aLocale- the given locale. - Returns:
 - a time formatter.
 
getDateInstance
public static final DateFormat getDateInstance()
FORMAT locale. This is equivalent to calling getDateInstance(DEFAULT,
     Locale.getDefault(Locale.Category.FORMAT)).
- Returns:
 - a date formatter.
 - See Also:
 
getDateInstance
public static final DateFormat getDateInstance(int style)
FORMAT locale. This is equivalent to calling getDateInstance(style,
     Locale.getDefault(Locale.Category.FORMAT)).
- Parameters:
 - 
style- the given formatting style. For example, SHORT for "M/d/yy" in the US locale. - Returns:
 - a date formatter.
 - See Also:
 
getDateInstance
public static final DateFormat getDateInstance(int style, Locale aLocale)
- Parameters:
 - 
style- the given formatting style. For example, SHORT for "M/d/yy" in the US locale. - 
aLocale- the given locale. - Returns:
 - a date formatter.
 
getDateTimeInstance
public static final DateFormat getDateTimeInstance()
FORMAT locale. This is equivalent to calling getDateTimeInstance(DEFAULT,
     DEFAULT, Locale.getDefault(Locale.Category.FORMAT)).
- Returns:
 - a date/time formatter.
 - See Also:
 
getDateTimeInstance
public static final DateFormat getDateTimeInstance(int dateStyle, int timeStyle)
FORMAT locale. This is equivalent to calling getDateTimeInstance(dateStyle,
     timeStyle, Locale.getDefault(Locale.Category.FORMAT)).
- Parameters:
 - 
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. - Returns:
 - a date/time formatter.
 - See Also:
 
getDateTimeInstance
public static final DateFormat getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale)
- Parameters:
 - 
dateStyle- the given date formatting style. - 
timeStyle- the given time formatting style. - 
aLocale- the given locale. - Returns:
 - a date/time formatter.
 
getInstance
public static final DateFormat getInstance()
- Returns:
 - a date/time formatter
 
getAvailableLocales
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.- Returns:
 - An array of locales for which localized 
DateFormatinstances are available. 
setCalendar
public void setCalendar(Calendar newCalendar)
Any TimeZone and leniency values that have previously been set are overwritten by newCalendar's values.
- Parameters:
 - 
newCalendar- the newCalendarto be used by the date format 
getCalendar
public Calendar getCalendar()
- Returns:
 - the calendar associated with this date/time formatter.
 
setNumberFormat
public void setNumberFormat(NumberFormat newNumberFormat)
- Parameters:
 - 
newNumberFormat- the given new NumberFormat. 
getNumberFormat
public NumberFormat getNumberFormat()
- Returns:
 - the number formatter which this date/time formatter uses.
 
setTimeZone
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.
- Parameters:
 - 
zone- the given new time zone. 
getTimeZone
public TimeZone getTimeZone()
getCalendar().getTimeZone()
- Returns:
 - the time zone associated with the calendar of DateFormat.
 
setLenient
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().
- Parameters:
 - 
lenient- whentrue, parsing is lenient - See Also:
 
isLenient
public boolean isLenient()
getCalendar().isLenient()
- Returns:
 - 
trueif thecalendaris lenient;falseotherwise. - See Also:
 
hashCode
public int hashCode()
equals
public boolean equals(Object obj)
clone
public Object clone()
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    https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/text/DateFormat.html