Class DateFormat

java.lang.Object
java.text.Format
java.text.DateFormat
All Implemented Interfaces:
Serializable,Cloneable
Direct Known Subclasses:
SimpleDateFormat
public abstract classDateFormatextendsFormat
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 asSimpleDateFormat, allows for formatting (i.e., date → text), parsing (text → date), and normalization. The date is represented as aDate object or as the milliseconds since January 1, 1970, 00:00:00 GMT.

DateFormat provides static factory methods for obtaining default date/time formatters based on the default or a given locale and a number of formatting styles. The formatting styles includeFULL,LONG,MEDIUM, andSHORT. For any of the factory methods with the parameterstyle, an IllegalArgumentException will be thrown ifstyle is not equal to any of the defined formatting styles. 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 (Date myDate : dates) {    output.println(df.format(myDate) + "; ");}

To format a date for a different Locale, specify it in the call togetDateInstance().

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);

UsegetDateInstance to get the normal date format for that country. There are other static factory methods available. UsegetTimeInstance to get the time format for that country. UsegetDateTimeInstance to get a date and time format. You can pass in different options to these factory methods to control the length of the result; fromSHORT toMEDIUM toLONG toFULL. The exact result depends on the locale, but generally:

  • SHORT is the shortest and mainly numeric, such as12.13.52 or3:30pm
  • MEDIUM is longer, such asJan 12, 1952
  • LONG is even longer, such asJanuary 12, 1952 or3:30:32pm
  • FULL is the longest, such asTuesday, April 12, 1952 AD or 3:30:42pm PST.
For those fields with text, typically abbreviated text form is used withMEDIUM option, and full text form is used withLONG andFULL options.

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 theDateFormat you get from the factory methods to aSimpleDateFormat. This will work for the majority of countries; just remember to put it in atry block in case you encounter an unusual one.

You can also use forms of the parse and format methods withParsePosition andFieldPosition 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 usingDateTimeFormatter as an immutable and thread-safe alternative.
Implementation Requirements:
Since:
1.1
See Also:

  • Field Details

    • calendar

      protected Calendar calendar
      TheCalendar 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 aCalendar appropriate for theLocale associated with thisDateFormat.

    • numberFormat

      protected NumberFormat numberFormat
      The number formatter thatDateFormat uses to format numbers in dates and times. Subclasses should initialize this to a number format appropriate for the locale associated with thisDateFormat.

    • ERA_FIELD

      public static final int ERA_FIELD
      Useful constant for ERA field alignment. Used in FieldPosition of date/time formatting.
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    • YEAR_FIELD

      public static final int YEAR_FIELD
      Useful constant for YEAR field alignment. Used in FieldPosition of date/time formatting.
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    • MONTH_FIELD

      public static final int MONTH_FIELD
      Useful constant for MONTH field alignment. Used in FieldPosition of date/time formatting.
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    • DATE_FIELD

      public static final int DATE_FIELD
      Useful constant for DATE field alignment. Used in FieldPosition of date/time formatting.
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    • 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.
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    • 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.
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    • MINUTE_FIELD

      public static final int MINUTE_FIELD
      Useful constant for MINUTE field alignment. Used in FieldPosition of date/time formatting.
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    • SECOND_FIELD

      public static final int SECOND_FIELD
      Useful constant for SECOND field alignment. Used in FieldPosition of date/time formatting.
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    • MILLISECOND_FIELD

      public static final int MILLISECOND_FIELD
      Useful constant for MILLISECOND field alignment. Used in FieldPosition of date/time formatting.
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    • 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.
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    • 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.
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    • 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.
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    • 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.
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    • 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.
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    • AM_PM_FIELD

      public static final int AM_PM_FIELD
      Useful constant for AM_PM field alignment. Used in FieldPosition of date/time formatting.
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    • 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.
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    • 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.
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    • TIMEZONE_FIELD

      public static final int TIMEZONE_FIELD
      Useful constant for TIMEZONE field alignment. Used in FieldPosition of date/time formatting.
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    • FULL

      public static final int FULL
      Constant for full style pattern.
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    • LONG

      public static final int LONG
      Constant for long style pattern.
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    • MEDIUM

      public static final int MEDIUM
      Constant for medium style pattern.
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    • SHORT

      public static final int SHORT
      Constant for short style pattern.
      See Also:

    • DEFAULT

      public static final int DEFAULT
      Constant for default style pattern. Its value is MEDIUM.
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  • Constructor Details

    • DateFormat

      protected DateFormat()
      Create a new date format.

  • Method Details

    • format

      public final StringBuffer format(Object obj,StringBuffer toAppendTo,FieldPosition fieldPosition)
      Formats the givenObject into a date-time string. The formatted string is appended to the givenStringBuffer.
      Specified by:
      format in class Format
      Parameters:
      obj - Must be aDate or aNumber representing a millisecond offset from theEpoch.
      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 givenfieldPosition isYEAR_FIELD, the begin index and end index offieldPosition will be set to 0 and 4, respectively. Notice that if the same date-time field appears more than once in a pattern, thefieldPosition will be set for the first occurrence of that date-time field. For instance, formatting aDate to 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 offieldPosition will be set to 5 and 8, respectively, for the first occurrence of the timezone pattern character'z'.
      Returns:
      the string buffer passed in astoAppendTo, with formatted text appended.
      Throws:
      IllegalArgumentException - if theFormat cannot format the givenobj.
      See Also:

    • format

      public abstract StringBuffer format(Date date,StringBuffer toAppendTo,FieldPosition fieldPosition)
      Formats aDate into a date-time string. The formatted string is appended to the givenStringBuffer.
      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 givenfieldPosition isYEAR_FIELD, the begin index and end index offieldPosition will be set to 0 and 4, respectively. Notice that if the same date-time field appears more than once in a pattern, thefieldPosition will be set for the first occurrence of that date-time field. For instance, formatting aDate to 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 offieldPosition will be set to 5 and 8, respectively, for the first occurrence of the timezone pattern character'z'.
      Returns:
      the string buffer passed in astoAppendTo, with formatted text appended.

    • format

      public final String format(Date date)
      Formats aDate 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) throwsParseException
      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 theparse(String, ParsePosition) method for more information on date parsing.

      Parameters:
      source - AString whose beginning should be parsed.
      Returns:
      ADate 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, ifthis has the pattern"M/d/yy h:m a, z", then a time text"07/10/96 4:5 PM, PDT" will be parsed into aDate that is equivalent toDate(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 callingsetLenient(false).

      This parsing operation uses thecalendar to produce aDate. As a result, thecalendar's date-time fields and theTimeZone value may have been overwritten, depending on subclass implementations. Any TimeZone value that has previously been set by a call tosetTimeZone 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:
      ADate, ornull if the input could not be parsed

    • parseObject

      public Object parseObject(String source,ParsePosition pos)
      Parses text from a string to produce aDate.

      The method attempts to parse text starting at the index given bypos. If parsing succeeds, then the index ofpos 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 updatedpos can be used to indicate the starting point for the next call to this method. If an error occurs, then the index ofpos is not changed, the error index ofpos is set to the index of the character where the error occurred, and null is returned.

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

      Specified by:
      parseObject in class Format
      Parameters:
      source - AString, part of which should be parsed.
      pos - AParsePosition object with index and error index information as described above.
      Returns:
      ADate parsed from the string. In case of error, returns null.
      Throws:
      NullPointerException - ifsource orpos is null.

    • getTimeInstance

      public static final DateFormat getTimeInstance()
      Gets the time formatter with the default formatting style for the defaultFORMAT locale.

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

      Returns:
      a time formatter.
      See Also:

    • getTimeInstance

      public static final DateFormat getTimeInstance(int style)
      Gets the time formatter with the given formatting style for the defaultFORMAT locale.

      This is equivalent to callinggetTimeInstance(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)
      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 defaultFORMAT locale.

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

      Returns:
      a date formatter.
      See Also:

    • getDateInstance

      public static final DateFormat getDateInstance(int style)
      Gets the date formatter with the given formatting style for the defaultFORMAT locale.

      This is equivalent to callinggetDateInstance(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)
      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 defaultFORMAT locale.

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

      Returns:
      a date/time formatter.
      See Also:

    • 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 defaultFORMAT locale.

      This is equivalent to callinggetDateTimeInstance(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)
      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.
      Returns:
      a date/time formatter

    • getAvailableLocales

      public static Locale[] getAvailableLocales()
      Returns an array of all locales for which theget*Instance methods of this class can return localized instances. The returned array represents the union of locales supported by the Java runtime and by installedDateFormatProvider implementations. At a minimum, the returned array must contain aLocale instance equal toLocale.ROOT and aLocale instance equal toLocale.US.
      Returns:
      An array of locales for which localizedDateFormat instances are available.

    • 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.

      AnyTimeZone andleniency values that have previously been set are overwritten bynewCalendar's values.

      Parameters:
      newCalendar - the newCalendar 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 thisDateFormat object. This method is equivalent to the following call.
      getCalendar().setTimeZone(zone);

      TheTimeZone set by this method is overwritten by asetCalendar call.

      TheTimeZone 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()
      Gets the time zone. This method is equivalent to the following call.
      getCalendar().getTimeZone();
      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.

      This method is equivalent to the following call.

      getCalendar().setLenient(lenient);

      This leniency value is overwritten by a call tosetCalendar().

      Implementation Requirements:
      ASPACE_SEPARATOR in the input text will match any otherSPACE_SEPARATORs in the pattern with lenient parsing; otherwise, it will not match.
      Parameters:
      lenient - whentrue, parsing is lenient
      See Also:

    • isLenient

      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 thecalendar is lenient;false otherwise.
      See Also:

    • hashCode

      public int hashCode()
      Returns the hash code for thisDateFormat.
      Overrides:
      hashCode in class Object
      Implementation Requirements:
      This method calculates the hash code value using the value returned bygetNumberFormat().
      Returns:
      the hash code for thisDateFormat
      See Also:

    • equals

      public boolean equals(Object obj)
      Compares the specified object with thisDateFormat for equality. Returns true if the object is also aDateFormat and the two formats would format any value the same.
      Overrides:
      equals in class Object
      Implementation Requirements:
      This method performs an equality check with a notion of class identity based ongetClass(), rather thaninstanceof. Therefore, in the equals methods in subclasses, no instance of this class should compare as equal to an instance of a subclass.
      Parameters:
      obj - object to be compared for equality
      Returns:
      true if the specified object is equal to thisDateFormat
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    • clone

      public Object clone()
      Overrides Cloneable
      Overrides:
      clone in class Format
      Returns:
      a clone of this instance.
      See Also: