DateFormat

  • DateFormat is an abstract class for formatting and parsing dates and times in a language-independent manner.

  • It provides methods for formatting dates to text, parsing text to dates, and normalizing date representations.

  • DateFormat offers features like locale sensitivity, formatting styles (FULL, LONG, MEDIUM, SHORT), and factory methods for creating formatters.

  • Subclasses such as SimpleDateFormat allow for customized date and time patterns, and it is related to classes like Calendar, TimeZone, and NumberFormat.

  • While not thread-safe by default, DateFormat can be configured for leniency during parsing and customized for greater control over formatting.
public abstract class DateFormat extends Format
Known Direct Subclasses

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

  • 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.

See Also

Nested Class Summary

class DateFormat.Field Defines constants that are used as attribute keys in the AttributedCharacterIterator returned from DateFormat.formatToCharacterIterator and as field identifiers in FieldPosition. 

Constant Summary

int AM_PM_FIELD Useful constant for AM_PM field alignment.
int DATE_FIELD Useful constant for DATE field alignment.
int DAY_OF_WEEK_FIELD Useful constant for DAY_OF_WEEK field alignment.
int DAY_OF_WEEK_IN_MONTH_FIELD Useful constant for DAY_OF_WEEK_IN_MONTH field alignment.
int DAY_OF_YEAR_FIELD Useful constant for DAY_OF_YEAR field alignment.
int DEFAULT Constant for default style pattern.
int ERA_FIELD Useful constant for ERA field alignment.
int FULL Constant for full style pattern.
int HOUR0_FIELD Useful constant for zero-based HOUR field alignment.
int HOUR1_FIELD Useful constant for one-based HOUR field alignment.
int HOUR_OF_DAY0_FIELD Useful constant for zero-based HOUR_OF_DAY field alignment.
int HOUR_OF_DAY1_FIELD Useful constant for one-based HOUR_OF_DAY field alignment.
int LONG Constant for long style pattern.
int MEDIUM Constant for medium style pattern.
int MILLISECOND_FIELD Useful constant for MILLISECOND field alignment.
int MINUTE_FIELD Useful constant for MINUTE field alignment.
int MONTH_FIELD Useful constant for MONTH field alignment.
int SECOND_FIELD Useful constant for SECOND field alignment.
int SHORT Constant for short style pattern.
int TIMEZONE_FIELD Useful constant for TIMEZONE field alignment.
int WEEK_OF_MONTH_FIELD Useful constant for WEEK_OF_MONTH field alignment.
int WEEK_OF_YEAR_FIELD Useful constant for WEEK_OF_YEAR field alignment.
int YEAR_FIELD Useful constant for YEAR field alignment.

Field Summary

protected Calendar calendar The Calendar instance used for calculating the date-time fields and the instant of time.
protected NumberFormat numberFormat The number formatter that DateFormat uses to format numbers in dates and times.

Protected Constructor Summary

DateFormat()
Create a new date format.

Public Method Summary

Object
clone()
Overrides Cloneable
boolean
equals(Object obj)
Overrides equals
final StringBuffer
format(Object obj, StringBuffer toAppendTo, FieldPosition fieldPosition)
Overrides Format.
abstract StringBuffer
format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition)
Formats a Date into a date/time string.
final String
format(Date date)
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.
final static DateFormat
getDateInstance(int style, Locale aLocale)
Gets the date formatter with the given formatting style for the given locale.
final static DateFormat
getDateInstance(int style)
Gets the date formatter with the given formatting style for the default FORMAT locale.
final static DateFormat
getDateInstance()
Gets the date formatter with the default formatting style for the default FORMAT locale.
final static DateFormat
getDateTimeInstance(int dateStyle, int timeStyle)
Gets the date/time formatter with the given date and time formatting styles for the default FORMAT locale.
final static DateFormat
getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale)
Gets the date/time formatter with the given formatting styles for the given locale.
final static DateFormat
getDateTimeInstance()
Gets the date/time formatter with the default formatting style for the default FORMAT locale.
final 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.
final static DateFormat
getTimeInstance(int style)
Gets the time formatter with the given formatting style for the default FORMAT locale.
final static DateFormat
getTimeInstance(int style, Locale aLocale)
Gets the time formatter with the given formatting style for the given locale.
final static DateFormat
getTimeInstance()
Gets the time formatter with the default formatting style for the default FORMAT 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.

Inherited Method Summary

Constants

public static final int AM_PM_FIELD

Useful constant for AM_PM field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 14

public static final int DATE_FIELD

Useful constant for DATE field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 3

public static final int DAY_OF_WEEK_FIELD

Useful constant for DAY_OF_WEEK field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 9

public static final int DAY_OF_WEEK_IN_MONTH_FIELD

Useful constant for DAY_OF_WEEK_IN_MONTH field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 11

public static final int DAY_OF_YEAR_FIELD

Useful constant for DAY_OF_YEAR field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 10

public static final int DEFAULT

Constant for default style pattern. Its value is MEDIUM.

Constant Value: 2

public static final int ERA_FIELD

Useful constant for ERA field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 0

public static final int FULL

Constant for full style pattern.

Constant Value: 0

public static final int HOUR0_FIELD

Useful constant for zero-based HOUR field alignment. Used in FieldPosition of date/time formatting. HOUR0_FIELD is used for the zero-based 12-hour clock. For example, 11:30 PM + 1 hour results in 00:30 AM.

Constant Value: 16

public static final int HOUR1_FIELD

Useful constant for one-based HOUR field alignment. Used in FieldPosition of date/time formatting. HOUR1_FIELD is used for the one-based 12-hour clock. For example, 11:30 PM + 1 hour results in 12:30 AM.

Constant Value: 15

public static final int HOUR_OF_DAY0_FIELD

Useful constant for zero-based HOUR_OF_DAY field alignment. Used in FieldPosition of date/time formatting. HOUR_OF_DAY0_FIELD is used for the zero-based 24-hour clock. For example, 23:59 + 01:00 results in 00:59.

Constant Value: 5

public static final int HOUR_OF_DAY1_FIELD

Useful constant for one-based HOUR_OF_DAY field alignment. Used in FieldPosition of date/time formatting. HOUR_OF_DAY1_FIELD is used for the one-based 24-hour clock. For example, 23:59 + 01:00 results in 24:59.

Constant Value: 4

public static final int LONG

Constant for long style pattern.

Constant Value: 1

public static final int MEDIUM

Constant for medium style pattern.

Constant Value: 2

public static final int MILLISECOND_FIELD

Useful constant for MILLISECOND field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 8

public static final int MINUTE_FIELD

Useful constant for MINUTE field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 6

public static final int MONTH_FIELD

Useful constant for MONTH field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 2

public static final int SECOND_FIELD

Useful constant for SECOND field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 7

public static final int SHORT

Constant for short style pattern.

Constant Value: 3

public static final int TIMEZONE_FIELD

Useful constant for TIMEZONE field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 17

public static final int WEEK_OF_MONTH_FIELD

Useful constant for WEEK_OF_MONTH field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 13

public static final int WEEK_OF_YEAR_FIELD

Useful constant for WEEK_OF_YEAR field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 12

public static final int YEAR_FIELD

Useful constant for YEAR field alignment. Used in FieldPosition of date/time formatting.

Constant Value: 1

Fields

protected Calendar calendar

The Calendar instance used for calculating the date-time fields and the instant of time. This field is used for both formatting and parsing.

Subclasses should initialize this field to a Calendar appropriate for the Locale associated with this DateFormat.

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.

Protected Constructors

protected DateFormat ()

Create a new date format.

Public Methods

public Object clone ()

Overrides Cloneable

Returns
  • a clone of this instance.

public boolean equals (Object obj)

Overrides equals

Parameters
obj the object to compare this instance with.
Returns
  • true if the specified object is equal to this Object; false otherwise.

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.

Parameters
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'.
Returns
  • the string buffer passed in as toAppendTo, with formatted text appended.
See Also

public abstract StringBuffer format (Date date, StringBuffer toAppendTo, FieldPosition fieldPosition)

Formats a Date into a date/time string.

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 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'.
Returns
  • the string buffer passed in as toAppendTo, with formatted text appended.

public final String format (Date date)

Formats a Date into a date/time string.

Parameters
date the time value to be formatted into a time string.
Returns
  • the formatted time string.

public static Locale[] getAvailableLocales ()

Returns an array of all locales for which the get*Instance methods of this class can return localized instances.

Returns
  • An array of locales for which localized DateFormat instances are available.

public Calendar getCalendar ()

Gets the calendar associated with this date/time formatter.

Returns
  • the calendar associated with this date/time formatter.

public static final DateFormat getDateInstance (int style, Locale aLocale)

Gets the date formatter with the given formatting style for the given locale.

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.

public static final DateFormat getDateInstance (int style)

Gets the date formatter with the given formatting style for the default 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

public static final DateFormat getDateInstance ()

Gets the date formatter with the default formatting style for the default FORMAT locale.

This is equivalent to calling getDateInstance(DEFAULT, Locale.getDefault(Locale.Category.FORMAT)).

Returns
  • a date formatter.
See Also

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 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

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.

Parameters
dateStyle the given date formatting style.
timeStyle the given time formatting style.
aLocale the given locale.
Returns
  • a date/time formatter.

public static final DateFormat getDateTimeInstance ()

Gets the date/time formatter with the default formatting style for the default FORMAT locale.

This is equivalent to calling getDateTimeInstance(DEFAULT, DEFAULT, Locale.getDefault(Locale.Category.FORMAT)).

Returns
  • a date/time formatter.
See Also

public static final DateFormat getInstance ()

Get a default date/time formatter that uses the SHORT style for both the date and the time.

Returns
  • a date/time formatter

public NumberFormat getNumberFormat ()

Gets the number formatter which this date/time formatter uses to format and parse a time.

Returns
  • the number formatter which this date/time formatter uses.

public static final DateFormat getTimeInstance (int style)

Gets the time formatter with the given formatting style for the default 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

public static final DateFormat getTimeInstance (int style, Locale aLocale)

Gets the time formatter with the given formatting style for the given locale.

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.

public static final DateFormat getTimeInstance ()

Gets the time formatter with the default formatting style for the default FORMAT locale.

This is equivalent to calling getTimeInstance(DEFAULT, Locale.getDefault(Locale.Category.FORMAT)).

Returns
  • a time formatter.
See Also

public TimeZone getTimeZone ()

Gets the time zone. This method is equivalent to the following call. 

getCalendar().getTimeZone()

Returns
  • the time zone associated with the calendar of DateFormat.

public int hashCode ()

Overrides hashCode

Returns
  • this object's hash code.

public boolean isLenient ()

Tell whether date/time parsing is to be lenient. This method is equivalent to the following call. 

getCalendar().isLenient()

Returns
  • true if the calendar is lenient; false otherwise.
See Also

public Date parse (String source)

Parses text from the beginning of the given string to produce a date. The method may not use the entire text of the given string.

See the parse(String, ParsePosition) method for more information on date parsing.

Parameters
source A String whose beginning should be parsed.
Returns
  • A Date parsed from the string.
Throws
ParseException if the beginning of the specified string cannot be parsed.

public abstract Date parse (String source, 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(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, or null if the input could not be parsed

public Object parseObject (String source, ParsePosition pos)

Parses text from a string to produce a 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.

Parameters
source A String, part of which should be parsed.
pos A ParsePosition object with index and error index information as described above.
Returns
  • A Date parsed from the string. In case of error, returns null.
Throws
NullPointerException if pos is null.

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.

Any TimeZone and {@linkplain #isLenient() leniency} values that have previously been set are overwritten by newCalendar's values.

Parameters
newCalendar the new Calendar to be used by the date format

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.

This method is equivalent to the following call. 

getCalendar().setLenient(lenient)

This leniency value is overwritten by a call to setCalendar().

Parameters
lenient when true, parsing is lenient
See Also

public void setNumberFormat (NumberFormat newNumberFormat)

Allows you to set the number formatter.

Parameters
newNumberFormat the given new NumberFormat.

public void setTimeZone (TimeZone zone)

Sets the time zone for the calendar of this 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.