java.text
Class DateFormat

java.lang.Object
  |
  +--java.text.Format
        |
        +--java.text.DateFormat

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 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 < a.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(Locale.FRANCE);
 

You can use a DateFormat to parse also.

  myDate = df.parse(myString);
 

Use getDate to get the normal date format for that country. There are other static factory methods available. Use getTime to get the time format for that country. Use getDateTime 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.

See Also:

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

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 text) Parse a date/time string.
abstract Date	parse(String text, ParsePosition pos) Parse a date/time string according to the given parse position.
Object	parseObject(String source, ParsePosition pos) Parse a date/time string into an Object.
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, 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.

YEAR_FIELD

public static final int YEAR_FIELD

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

MONTH_FIELD

public static final int MONTH_FIELD

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

DATE_FIELD

public static final int DATE_FIELD

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

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.

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.

MINUTE_FIELD

public static final int MINUTE_FIELD

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

SECOND_FIELD

public static final int SECOND_FIELD

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

MILLISECOND_FIELD

public static final int MILLISECOND_FIELD

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

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.

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.

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.

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.

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.

AM_PM_FIELD

public static final int AM_PM_FIELD

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

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.

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.

TIMEZONE_FIELD

public static final int TIMEZONE_FIELD

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

FULL

public static final int FULL

Constant for full style pattern.

LONG

public static final int LONG

Constant for long style pattern.

MEDIUM

public static final int MEDIUM

Constant for medium style pattern.

SHORT

public static final int SHORT

Constant for short style pattern.

DEFAULT

public static final int DEFAULT

Constant for default style pattern.

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.

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 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'.

Returns:

the formatted time string.

Overrides:

format in class Format

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 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'.

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 text)
           throws ParseException

Parse a date/time string.

Parameters:

text - The date/time string to be parsed

Returns:

A Date, or null if the input could not be parsed

Throws:

ParseException - If the given string cannot be parsed as a date.

See Also:

parse(String, ParsePosition)

parse

public abstract 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).

Parameters:

text - 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)

Parse a date/time string into an Object. This convenience method simply calls parse(String, ParsePosition).

Overrides:

parseObject in class Format

See Also:

parse(String, ParsePosition)

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

equals

public boolean equals(Object obj)

Overrides equals

Overrides:

equals in class Object

clone

public Object clone()

Overrides Cloneable

Overrides:

clone in class Format