DateFormat

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## java.text
Class DateFormat

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

All Implemented Interfaces:
  Serializable, Cloneable

Direct Known Subclasses:
  SimpleDateFormat

    public abstract class DateFormat

extends Format

DateFormat is an abstract class for date/time formatting subclasses which formats and parses dates or time in a language-independent manner. The date/time formatting subclass, such as SimpleDateFormat, allows for formatting (i.e., date -> text), parsing (text -> date), and normalization. The date is represented as a `Date` object or as the milliseconds since January 1, 1970, 00:00:00 GMT.

DateFormat provides many class methods for obtaining default date/time formatters based on the default or a given locale and a number of formatting styles. The formatting styles include FULL, LONG, MEDIUM, and SHORT. More detail and examples of using these styles are provided in the method descriptions.

DateFormat helps you to format and parse dates for any locale. Your code can be completely independent of the locale conventions for months, days of the week, or even the calendar format: lunar vs. solar.

To format a date for the current Locale, use one of the static factory methods:

      myString = DateFormat.getDateInstance().format(myDate);

If you are formatting multiple dates, it is more efficient to get the format and use it multiple times so that the system doesn't have to fetch the information about the local language and country conventions multiple times.

      DateFormat df = DateFormat.getDateInstance();
      for (int i = 0; i < 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.

Version:
  1.44, 10/25/05
Author:
  Mark Davis, Chen-Lieh Huang, Alan Liu
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.
`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.
`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.

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
`getClass, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### 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

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.
  See Also:
    `Cloneable`

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