Added in API level 1

Summary: Nested Classes | Protected Ctors | Methods | Inherited Methods

Format

public abstract class Format
extends Object implements Cloneable, Serializable

java.lang.Object
↳	java.text.Format

Known direct subclasses DateFormat, MessageFormat, NumberFormat, SelectFormat, UFormat DateFormat DateFormat is an abstract class for date/time formatting subclasses which formats and parses dates or time in a language-independent manner.  MessageFormat MessageFormat provides a means to produce concatenated messages in a language-neutral way.  NumberFormat NumberFormat is the abstract base class for all number formats.  SelectFormat SelectFormat supports the creation of internationalized messages by selecting phrases based on keywords.  UFormat An abstract class that extends Format to provide additional ICU protocol, specifically, the getLocale() API.

Known indirect subclasses ChoiceFormat, CompactDecimalFormat, DateFormat, DateIntervalFormat, DecimalFormat, MeasureFormat, MessageFormat, NumberFormat, PluralFormat, SimpleDateFormat, TimeZoneFormat ChoiceFormat A ChoiceFormat allows you to attach a format to a range of numbers.  CompactDecimalFormat Formats numbers in compact (abbreviated) notation, like "1.2K" instead of "1200".  DateFormat [icu enhancement] ICU's replacement for DateFormat. Methods, fields, and other functionality specific to ICU are labeled '[icu]'.  DateIntervalFormat DateIntervalFormat is a class for formatting and parsing date intervals in a language-independent manner.  DecimalFormat [icu enhancement] ICU's replacement for DecimalFormat. Methods, fields, and other functionality specific to ICU are labeled '[icu]'.  MeasureFormat A formatter for Measure objects.  MessageFormat [icu enhancement] ICU's replacement for MessageFormat. Methods, fields, and other functionality specific to ICU are labeled '[icu]'.  NumberFormat [icu enhancement] ICU's replacement for NumberFormat. Methods, fields, and other functionality specific to ICU are labeled '[icu]'.  PluralFormat PluralFormat supports the creation of internationalized messages with plural inflection.  SimpleDateFormat [icu enhancement] ICU's replacement for SimpleDateFormat. Methods, fields, and other functionality specific to ICU are labeled '[icu]'.  TimeZoneFormat TimeZoneFormat supports time zone display name formatting and parsing.

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Format is an abstract base class for formatting locale-sensitive information such as dates, messages, and numbers.

Format defines the programming interface for formatting locale-sensitive objects into Strings (the format method) and for parsing Strings back into objects (the parseObject method).

Generally, a format's parseObject method must be able to parse any string formatted by its format method. However, there may be exceptional cases where this is not possible. For example, a format method might create two adjacent integer numbers with no separator in between, and in this case the parseObject could not tell which digits belong to which number.

Subclassing

The Java Platform provides three specialized subclasses of Format-- DateFormat, MessageFormat, and NumberFormat--for formatting dates, messages, and numbers, respectively.

Concrete subclasses must implement three methods:

1. format(Object obj, StringBuffer toAppendTo, FieldPosition pos)
2. formatToCharacterIterator(Object obj)
3. parseObject(String source, ParsePosition pos)

These general methods allow polymorphic parsing and formatting of objects and are used, for example, by MessageFormat. Subclasses often also provide additional format methods for specific input types as well as parse methods for specific result types. Any parse method that does not take a ParsePosition argument should throw ParseException when no text in the required format is at the beginning of the input text.

Most subclasses will also implement the following factory methods:

1. getInstance for getting a useful format object appropriate for the current locale
2. getInstance(Locale) for getting a useful format object appropriate for the specified locale

In addition, some subclasses may also implement other getXxxxInstance methods for more specialized control. For example, the NumberFormat class provides getPercentInstance and getCurrencyInstance methods for getting specialized number formatters.

Subclasses of Format that allow programmers to create objects for locales (with getInstance(Locale) for example) must also implement the following class method:

 public static Locale[] getAvailableLocales()
 

And finally subclasses may define a set of constants to identify the various fields in the formatted output. These constants are used to create a FieldPosition object which identifies what information is contained in the field and its position in the formatted result. These constants should be named item_FIELD where item identifies the field. For examples of these constants, see ERA_FIELD and its friends in DateFormat.

Synchronization

Formats are generally 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:

• ParsePosition
• FieldPosition
• NumberFormat
• DateFormat
• MessageFormat

Summary

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

Protected constructors
Format() Sole constructor.

Public methods
Object	clone() Creates and returns a copy of this object.
final String	format(Object obj) Formats an object to produce a string.
abstract StringBuffer	format(Object obj, StringBuffer toAppendTo, FieldPosition pos) Formats an object and appends the resulting text to a given string buffer.
AttributedCharacterIterator	formatToCharacterIterator(Object obj) Formats an Object producing an AttributedCharacterIterator.
Object	parseObject(String source) Parses text from the beginning of the given string to produce an object.
abstract Object	parseObject(String source, ParsePosition pos) Parses text from a string to produce an object.

Inherited methods

From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Protected constructors

Format

Added in API level 1

protected Format ()

Sole constructor. (For invocation by subclass constructors, typically implicit.)

Public methods

clone

Added in API level 1

public Object clone ()

Creates and returns a copy of this object.

Returns
Object	a clone of this instance.

format

Added in API level 1

public final String format (Object obj)

Formats an object to produce a string. This is equivalent to

format(obj, new StringBuffer(), new FieldPosition(0)).toString();

Parameters
obj	Object: The object to format

Returns
String	Formatted string.

Throws
IllegalArgumentException	if the Format cannot format the given object

format

Added in API level 1

public abstract StringBuffer format (Object obj, 
                StringBuffer toAppendTo, 
                FieldPosition pos)

Formats an object and appends the resulting text to a given string buffer. If the pos argument identifies a field used by the format, then its indices are set to the beginning and end of the first such field encountered.

Parameters
obj	Object: The object to format
toAppendTo	StringBuffer: where the text is to be appended
pos	FieldPosition: A FieldPosition identifying a field in the formatted text

Returns
StringBuffer	the string buffer passed in as toAppendTo, with formatted text appended

Throws
NullPointerException	if toAppendTo or pos is null
IllegalArgumentException	if the Format cannot format the given object

formatToCharacterIterator

Added in API level 1

public AttributedCharacterIterator formatToCharacterIterator (Object obj)

Formats an Object producing an AttributedCharacterIterator. You can use the returned AttributedCharacterIterator to build the resulting String, as well as to determine information about the resulting String.

Each attribute key of the AttributedCharacterIterator will be of type Field. It is up to each Format implementation to define what the legal values are for each attribute in the AttributedCharacterIterator, but typically the attribute key is also used as the attribute value.

The default implementation creates an AttributedCharacterIterator with no attributes. Subclasses that support fields should override this and create an AttributedCharacterIterator with meaningful attributes.

Parameters
obj	Object: The object to format

Returns
AttributedCharacterIterator	AttributedCharacterIterator describing the formatted value.

Throws
NullPointerException	if obj is null.
IllegalArgumentException	when the Format cannot format the given object.

parseObject

Added in API level 1

public Object parseObject (String source)

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

Parameters
source	String: A String whose beginning should be parsed.

Returns
Object	An Object parsed from the string.

Throws
ParseException	if the beginning of the specified string cannot be parsed.
NullPointerException	if source is null.

parseObject

Added in API level 1

public abstract Object parseObject (String source, 
                ParsePosition pos)

Parses text from a string to produce an object.

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 object 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.

Parameters
source	String: A String, part of which should be parsed.
pos	ParsePosition: A ParsePosition object with index and error index information as described above.

Returns
Object	An Object parsed from the string. In case of error, returns null.

Throws
NullPointerException	if source or pos is null.