java.text
Class DateFormat

java.lang.Object
  java.text.Format
      java.text.DateFormat

All Implemented Interfaces:

Cloneable, Serializable

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 < a.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:

Format, NumberFormat, SimpleDateFormat, Calendar, GregorianCalendar, TimeZone, Serialized Form

Nested Class Summary

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

static int	AM_PM_FIELD Useful constant for AM_PM field alignment.
protected Calendar	calendar The calendar that DateFormat uses to produce the time field values needed to implement date and time formatting.
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.

Constructor Summary

protected

DateFormat() Create a new date format.

Method Summary

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() Gets the set of locales for which DateFormats are installed.
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.

Methods inherited from class java.text.Format

format, formatToCharacterIterator, parseObject

Methods inherited from class java.lang.Object

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

Field Detail

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.

ERA_FIELD

public static final int ERA_FIELD

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

See Also:

Constant Field Values

YEAR_FIELD

public static final int YEAR_FIELD

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

See Also:

Constant Field Values

MONTH_FIELD

public static final int MONTH_FIELD

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

See Also:

Constant Field Values

DATE_FIELD

public static final int DATE_FIELD

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

See Also:

Constant Field Values

HOUR_OF_DAY1_FIELD

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.

See Also:

Constant Field Values

HOUR_OF_DAY0_FIELD

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.

See Also:

Constant Field Values

MINUTE_FIELD

public static final int MINUTE_FIELD

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

See Also:

Constant Field Values

SECOND_FIELD

public static final int SECOND_FIELD

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

See Also:

Constant Field Values

MILLISECOND_FIELD

public static final int MILLISECOND_FIELD

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

See Also:

Constant Field Values

DAY_OF_WEEK_FIELD

public static final int DAY_OF_WEEK_FIELD

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

See Also:

Constant Field Values

DAY_OF_YEAR_FIELD

public static final int DAY_OF_YEAR_FIELD

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

See Also:

Constant Field Values

DAY_OF_WEEK_IN_MONTH_FIELD

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.

See Also:

Constant Field Values

WEEK_OF_YEAR_FIELD

public static final int WEEK_OF_YEAR_FIELD

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

See Also:

Constant Field Values

WEEK_OF_MONTH_FIELD

public static final int WEEK_OF_MONTH_FIELD

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

See Also:

Constant Field Values

AM_PM_FIELD

public static final int AM_PM_FIELD

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

See Also:

Constant Field Values

HOUR1_FIELD

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.

See Also:

Constant Field Values

HOUR0_FIELD

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.

See Also:

Constant Field Values

TIMEZONE_FIELD

public static final int TIMEZONE_FIELD

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

See Also:

Constant Field Values

FULL

public static final int FULL

Constant for full style pattern.

See Also:

Constant Field Values

LONG

public static final int LONG

Constant for long style pattern.

See Also:

Constant Field Values

MEDIUM

public static final int MEDIUM

Constant for medium style pattern.

See Also:

Constant Field Values

SHORT

public static final int SHORT

Constant for short style pattern.

See Also:

Constant Field Values

DEFAULT

public static final int DEFAULT

Constant for default style pattern. Its value is MEDIUM.

See Also:

Constant Field Values

Constructor Detail

DateFormat

protected DateFormat()

Create a new date format.

Method Detail

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.

Specified by:

format in class Format

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 formatted time string.

See Also:

Format

format

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 formatted date/time string.

format

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.

parse

public Date parse(String source)
           throws ParseException

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.

parse

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(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).

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

See Also:

setLenient(boolean)

parseObject

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.

Specified by:

parseObject in class Format

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.

getTimeInstance

public static final DateFormat getTimeInstance()

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

Returns:

a time formatter.

getTimeInstance

public static final DateFormat getTimeInstance(int style)

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

Parameters:

style - the given formatting style. For example, SHORT for "h:mm a" in the US locale.

Returns:

a time formatter.

getTimeInstance

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.

getDateInstance

public static final DateFormat getDateInstance()

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

Returns:

a date formatter.

getDateInstance

public static final DateFormat getDateInstance(int style)

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

Parameters:

style - the given formatting style. For example, SHORT for "M/d/yy" in the US locale.

Returns:

a date formatter.

getDateInstance

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.

getDateTimeInstance

public static final DateFormat getDateTimeInstance()

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

Returns:

a date/time formatter.

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.

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.

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.

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()

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

getAvailableLocales

public static Locale[] getAvailableLocales()

Gets the set of locales for which DateFormats are installed.

Returns:

the set of locales for which DateFormats are installed.

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.

Parameters:

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

getCalendar

public Calendar getCalendar()

Gets the calendar associated with this date/time formatter.

Returns:

the calendar associated with this date/time formatter.

setNumberFormat

public void setNumberFormat(NumberFormat newNumberFormat)

Allows you to set the number formatter.

Parameters:

newNumberFormat - the given new NumberFormat.

getNumberFormat

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.

setTimeZone

public void setTimeZone(TimeZone zone)

Sets the time zone for the calendar of this DateFormat object.

Parameters:

zone - the given new time zone.

getTimeZone

public TimeZone getTimeZone()

Gets the time zone.

Returns:

the time zone associated with the calendar of DateFormat.

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.

Parameters:

lenient - when true, parsing is lenient

See Also:

Calendar.setLenient(boolean)

isLenient

public boolean isLenient()

Tell whether date/time parsing is to be lenient.

hashCode

public int hashCode()

Overrides hashCode

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

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

equals

public boolean equals(Object obj)

Overrides equals

Overrides:

equals in class Object

Parameters:

obj - the reference object with which to compare.

Returns:

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

See Also:

Object.hashCode(), Hashtable

clone

public Object clone()

Overrides Cloneable

Overrides:

clone in class Format

Returns:

a clone of this instance.