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public final class

Formatter

extends Object
implements Closeable Flushable

java.lang.Object
↳	java.util.Formatter

Class Overview

The Formatter class is a String-formatting utility that is designed to work like the printf function of the C programming language. Its key methods are the format methods which create a formatted String by replacing a set of placeholders (format tokens) with formatted values. The style used to format each value is determined by the format token used. For example, the call
format("My decimal value is %d and my String is %s.", 3, "Hello");
returns the String
My decimal value is 3 and my String is Hello.

The format token consists of a percent sign, optionally followed by flags and precision arguments, and then a single character that indicates the type of value being formatted. If the type is a time/date, then the type character t is followed by an additional character that indicates how the date is to be formatted. The two characters <$ immediately following the % sign indicate that the previous value should be used again instead of moving on to the next value argument. A number n and a dollar sign immediately following the % sign make n the next argument to be used.

The available choices are the following:

Text value types
`s`	String	`format("%s, %s", "hello", "Hello");`	`hello, Hello`
`S`, `s`	String to capitals	`format("%S, %S", "hello", "Hello");`	`HELLO, HELLO`
`c`	Character	`format("%c, %c", 'd', 0x65);`	`d, e`
`C`	Character to capitals	`format("%C, %C", 'd', 0x65);`	`D, E`
Text option flags The value between the option and the type character indicates the minimum width in characters of the formatted value
`-`	Left justify (width value is required)	`format("%-3C, %3C", 'd', 0x65);`	`D , E`
Integer types
`d`	int, formatted as decimal	`format("%d, %d"1$, 35, 0x10);`	`35, 16`
`o`	int, formatted as octal	`format("%o, %o", 8, 010);`	`10, 10`
`X`, `x`	int, formatted as hexidecimal	`format("%x, %X", 10, 10);`	`a, A`
Integer option flags The value between the option and the type character indicates the minimum width in characters of the formatted value
`+`	lead with the number's sign	`format("%+d, %+4d", 5, 5);`	`+5, +5`
`-`	Left justify (width value is required)	`format("%-6dx", 5);`	`5 x`
`#`	Print the leading characters that indicate hexidecimal or octal (for use only with hex and octal types)	`format("%#o", 010);`	`010`
	A space indicates that non-negative numbers should have a leading space.	`format("x% d% 5d", 4, 4);`	`x 4 4`
`0`	Pad the number with leading zeros (width value is required)	`format("%07d, %03d", 4, 5555);`	`0000004, 5555`
`(`	Put parentheses around negative numbers (decimal only)	`format("%(d, %(d, %(6d", 12, -12, -12);`	`12, (12), (12)`
Float types A value immediately following the % symbol gives the minimum width in characters of the formatted value; if it is followed by a period and another integer, then the second value gives the precision (6 by default).
`f`	float (or double) formatted as a decimal, where the precision indicates the number of digits after the decimal.	`format("%f %<.1f %<1.5f %<10f %<6.0f", 123.456f);`	`123.456001 123.5 123.45600 123.456001 123`
`E`, `e`	float (or double) formatted in decimal exponential notation, where the precision indicates the number of significant digits.	`format("%E %<.1e %<1.5E %<10E %<6.0E", 123.456f);`	`1.234560E+02 1.2e+02 1.23456E+02 1.234560E+02 1E+02`
`G`, `g`	float (or double) formatted in decimal exponential notation , where the precision indicates the maximum number of significant digits.	`format("%G %<.1g %<1.5G %<10G %<6.0G", 123.456f);`	`123.456 1e+02 123.46 123.456 1E+02`
`A`, `a`	float (or double) formatted as a hexidecimal in exponential notation, where the precision indicates the number of significant digits.	`format("%A %<.1a %<1.5A %<10A %<6.0A", 123.456f);`	`0X1.EDD2F2P6 0x1.fp6 0X1.EDD2FP6 0X1.EDD2F2P6 0X1.FP6`
Float-type option flags See the Integer-type options. The options for float-types are the same as for integer types with one addition:
`,`	Use a comma in place of a decimal if the locale requires it.	`format(new Locale("fr"), "%,7.2f", 6.03f);`	`6,03`
Date types
`t`, `T`	Date	`format(new Locale("fr"), "%tB %TB", Calendar.getInstance(), Calendar.getInstance());`	`avril AVRIL`
Date format precisions The format precision character follows the `t`.
`A`, `a`	The day of the week	`format("%ta %tA", cal, cal);`	`Tue Tuesday`
`b`, `B`, `h`	The name of the month	`format("%tb %`	`Apr April Apr`
`C`	The century	`format("%tC\n", cal);`	`20`
`d`, `e`	The day of the month (with or without leading zeros)	`format("%td %te", cal, cal);`	`01 1`
`F`	The complete date formatted as YYYY-MM-DD	`format("%tF", cal);`	`2008-04-01`
`D`	The complete date formatted as MM/DD/YY (not corrected for locale)	`format(new Locale("en_US"), "%tD", cal); format(new Locale("en_UK"), " %tD", cal);`	`04/01/08 04/01/08`
`j`	The number of the day (from the beginning of the year).	`format("%tj\n", cal);`	`092`
`m`	The number of the month	`format("%tm\n", cal);`	`04`
`y`, `Y`	The year	`format("%ty %tY", cal, cal);`	`08 2008`
`H`, `I`, `k`, `l`	The hour of the day, in 12 or 24 hour format, with or without a leading zero	`format("%tH %tI %tk %tl", cal, cal, cal, cal);`	`16 04 16 4`
`p`	a.m. or p.m.	`format("%tp %Tp", cal, cal);`	`pm PM`
`M`, `S`, `L`, `N`	The minutes, seconds, milliseconds, and nanoseconds	`format("%tM %tS %tL %tN", cal, cal, cal, cal);`	`08 17 359 359000000`
`Z`, `z`	The time zone: its abbreviation or offset from GMT	`format("%tZ %tz", cal, cal);`	`CEST +0100`
`R`, `r`, `T`	The complete time	`format("%tR %tr %tT", cal, cal, cal);`	`16:15 04:15:32 PM 16:15:32`
`s`, `Q`	The number of seconds or milliseconds from "the epoch" (1 January 1970 00:00:00 UTC)	`format("%ts %tQ", cal, cal);`	`1207059412 1207059412656`
`c`	The complete time and date	`format("%tc", cal);`	`Tue Apr 01 16:19:17 CEST 2008`
Other data types
`B`, `b`	Boolean	`format("%b, %B", true, false);`	`true, FALSE`
`H`, `h`	Hashcode	`format("%h, %H", obj, obj);`	`190d11, 190D11`
`n`	line separator	`format("first%nsecond", "???");`	`first second`
Escape sequences
`%`	Escape the % character	`format("%d%%, %d", 50, 60);`	`50%, 60`

An instance of Formatter can be created to write the formatted output to standard types of output streams. Its functionality can also be accessed through the format methods of an output stream or of String:
System.out.println(String.format("%ty\n", cal));
System.out.format("%ty\n", cal);

The class is not multi-threaded safe. The user is responsible for maintaining a thread-safe design if a Formatter is accessed by multiple threads.

Summary

Nested Classes
public final class	Formatter.BigDecimalLayoutForm	The enumeration giving the available styles for formatting very large decimal numbers.

Public Constructors
	Formatter() Constructs a formatter.
	Formatter(Appendable a) Constructs a formatter of which the output is denoted.
	Formatter(Locale l) Constructs a formatter of which the locale is denoted.
	Formatter(Appendable a, Locale l) Constructs a formatter of which the output and locale is denoted.
	Formatter(String fileName) Constructs a formatter of which the filename is denoted.
	Formatter(String fileName, String csn) Constructs a formatter of which the filename and charset is denoted.
	Formatter(String fileName, String csn, Locale l) Constructs a formatter of which the filename, charset and locale is denoted.
	Formatter(File file) Constructs a formatter of which the file is denoted.
	Formatter(File file, String csn) Constructs a formatter of which the file and charset is denoted.
	Formatter(File file, String csn, Locale l) Constructs a formatter of which the file, charset and locale is denoted.
	Formatter(OutputStream os) Constructs a formatter of which the output destination is specified.
	Formatter(OutputStream os, String csn) Constructs a formatter of which the output destination and the charset is specified.
	Formatter(OutputStream os, String csn, Locale l) Constructs a formatter of which the output destination, the charset and the locale is specified.
	Formatter(PrintStream ps) Constructs a formatter of which the output destination is specified.

Public Methods
void	close() Closes the formatter.
void	flush() Flushes the formatter.
Formatter	format(Locale l, String format, Object... args) Writes a formatted string to the output destination of the formatter.
Formatter	format(String format, Object... args) Writes a formatted string to the output destination of the formatter.
IOException	ioException() Returns the last IOException thrown out by the formatter's output destination.
Locale	locale() Returns the locale of the formatter.
Appendable	out() Returns the output destination of the formatter.
String	toString() Returns the content by calling the toString() method of the output destination.

[Expand]

Inherited Methods

From class java.lang.Object

Object	clone() Returns a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o) Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison.
void	finalize() Called by the virtual machine when there are no longer any (non-weak) references to the receiver.
final Class<? extends Object>	getClass() Returns the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode() Returns an integer hash code for the receiver.
final void	notify() Causes one thread which is `wait` ing on the receiver to be made ready to run.
final void	notifyAll() Causes all threads which are `wait` ing on the receiver to be made ready to run.
String	toString() Returns a string containing a concise, human-readable description of the receiver.
final void	wait(long time, int frac) Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final void	wait(long time) Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final void	wait() Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by `notify` or `notifyAll`).

From interface java.io.Closeable

From interface java.io.Flushable

Public Constructors

public Formatter ()

Constructs a formatter. The output is a StringBuilder which can be achieved by invoking the out method and whose contents can be attained by calling the toString method. The locale for the formatter is the default locale of the JVM.

public Formatter (Appendable a)

Constructs a formatter of which the output is denoted. The locale for the formatter is the default locale of the JVM.

Parameters

a	The output of the formatter. If a is null, then a StringBuilder will be used.

public Formatter (Locale l)

Constructs a formatter of which the locale is denoted. The output destination is a StringBuilder which can be achieved by invoking the out method and whose contents can be attained by calling the toString method.

Parameters

l	The locale of the formatter. If l is null, then no localization will be used.

public Formatter (Appendable a, Locale l)

Constructs a formatter of which the output and locale is denoted.

Parameters

a	The output of the formatter. If a is null, then a StringBuilder will be used.
l	The locale of the formatter. If l is null, then no localization will be used.

public Formatter (String fileName)

Constructs a formatter of which the filename is denoted. The charset of the formatter is the default charset of JVM. The locale for the formatter is the default locale of the JVM.

Parameters

fileName	The filename of the file that is used as the output destination for the formatter. The file will be truncated to zero size if the file exists, or else a new file will be created. The output of the formatter is buffered.

Throws

FileNotFoundException	If the filename does not denote a normal and writable file, or a new file cannot be created or any error rises when opening or creating the file.
SecurityException	If there is a security manager and it denies writing to the file in checkWrite(file.getPath()).

public Formatter (String fileName, String csn)

Constructs a formatter of which the filename and charset is denoted. The locale for the formatter is the default locale of the JVM.

Parameters

fileName	The filename of the file that is used as the output destination for the formatter. The file will be truncated to zero size if the file exists, or else a new file will be created. The output of the formatter is buffered.
csn	The name of the charset for the formatter.

Throws

FileNotFoundException	If the filename does not denote a normal and writable file, or a new file cannot be created or any error rises when opening or creating the file.
SecurityException	If there is a security manager and it denies writing to the file in checkWrite(file.getPath()).
UnsupportedEncodingException	If the charset with the specified name is not supported.

public Formatter (String fileName, String csn, Locale l)

Constructs a formatter of which the filename, charset and locale is denoted.

Parameters

fileName	The filename of the file that is used as the output destination for the formatter. The file will be truncated to zero size if the file exists, or else a new file will be created. The output of the formatter is buffered.
csn	The name of the charset for the formatter.
l	The locale of the formatter. If l is null, then no localization will be used.

Throws

FileNotFoundException	If the filename does not denote a normal and writable file, or a new file cannot be created or any error rises when opening or creating the file.
SecurityException	If there is a security manager and it denies writing to the file in checkWrite(file.getPath()).
UnsupportedEncodingException	If the charset with the specified name is not supported.

public Formatter (File file)

Constructs a formatter of which the file is denoted. The charset of the formatter is the default charset of JVM. The locale for the formatter is the default locale of the JVM.

Parameters

file	The file that is used as the output destination for the formatter. The file will be truncated to zero size if the file exists, or else a new file will be created. The output of the formatter is buffered.

Throws

FileNotFoundException	If the file does not denote a normal and writable file, or a new file cannot be created or any error rises when opening or creating the file.
SecurityException	If there is a security manager and it denies writing to the file in checkWrite(file.getPath()).

public Formatter (File file, String csn)

Constructs a formatter of which the file and charset is denoted. The locale for the formatter is the default locale of the JVM.

Parameters

file	The file of the file that is used as the output destination for the formatter. The file will be truncated to zero size if the file exists, or else a new file will be created. The output of the formatter is buffered.
csn	The name of the charset for the formatter.

Throws

FileNotFoundException	If the file does not denote a normal and writable file, or a new file cannot be created or any error rises when opening or creating the file.
SecurityException	If there is a security manager and it denies writing to the file in checkWrite(file.getPath()).
UnsupportedEncodingException	If the charset with the specified name is not supported.

public Formatter (File file, String csn, Locale l)

Constructs a formatter of which the file, charset and locale is denoted.

Parameters

file	file that is used as the output destination for the formatter. The file will be truncated to zero size if the file exists, or else a new file will be created. The output of the formatter is buffered.
csn	The name of the charset for the formatter.
l	The locale of the formatter. If l is null, then no localization will be used.

Throws

FileNotFoundException	If the file does not denote a normal and writable file, or a new file cannot be created or any error rises when opening or creating the file.
SecurityException	If there is a security manager and it denies writing to the file in checkWrite(file.getPath()).
UnsupportedEncodingException	If the charset with the specified name is not supported.

public Formatter (OutputStream os)

Constructs a formatter of which the output destination is specified. The charset of the formatter is the default charset of JVM. The locale for the formatter is the default locale of the JVM.

Parameters

os	The stream used as the destination of the formatter.

public Formatter (OutputStream os, String csn)

Constructs a formatter of which the output destination and the charset is specified. The locale for the formatter is the default locale of the JVM.

Parameters

os	The stream used as the destination of the formatter.
csn	The name of the charset for the formatter.

Throws

UnsupportedEncodingException	If the charset with the specified name is not supported.

public Formatter (OutputStream os, String csn, Locale l)

Constructs a formatter of which the output destination, the charset and the locale is specified.

Parameters

os	The stream used as the destination of the formatter.
csn	The name of the charset for the formatter.
l	The locale of the formatter. If l is null, then no localization will be used.

Throws

UnsupportedEncodingException	If the charset with the specified name is not supported.

public Formatter (PrintStream ps)

Constructs a formatter of which the output destination is specified. The charset of the formatter is the default charset of JVM. The locale for the formatter is the default locale of the JVM.

Parameters

ps	The print stream used as destination of the formatter. If ps is null, then NullPointerExcepiton will be thrown out.

Public Methods

public void close ()

Closes the formatter. If the output destination is Closeable, then the method close() will be called on that destination. If the formatter has been closed, then calling the close will have no effect. Any method but the ioException() that is called after the formatter has been closed will raise a FormatterClosedException.

public void flush ()

Flushes the formatter. If the output destination is Flushable, then the method flush() will be called on that destination.

Throws

FormatterClosedException	If the formatter has been closed.

public Formatter format (Locale l, String format, Object... args)

Writes a formatted string to the output destination of the formatter.

Parameters

l	The locale used in the method. If locale is null, then no localization will be applied. This parameter does not influence the locale specified during construction.
format	A format string.
args	The arguments list used in the format() method. If there are more arguments than those specified by the format string, then the additional arguments are ignored.

Returns

This formatter.

Throws

IllegalFormatException	If the format string is illegal or incompatible with the arguments or the arguments are less than those required by the format string or any other illegal situation.
FormatterClosedException	If the formatter has been closed.

public Formatter format (String format, Object... args)

Writes a formatted string to the output destination of the formatter.

Parameters

format	A format string.
args	The arguments list used in the format() method. If there are more arguments than those specified by the format string, then the additional arguments are ignored.

Returns

This formatter.

Throws

IllegalFormatException	If the format string is illegal or incompatible with the arguments or the arguments are less than those required by the format string or any other illegal situation.
FormatterClosedException	If the formatter has been closed.

public IOException ioException ()

Returns the last IOException thrown out by the formatter's output destination. If the append() method of the destination will not throw IOException, the ioException() method will always return null.

Returns

The last IOException thrown out by the formatter's output destination.

public Locale locale ()

Returns the locale of the formatter.

Returns

The locale for the formatter and null for no locale.

Throws

FormatterClosedException	If the formatter has been closed.

public Appendable out ()

Returns the output destination of the formatter.

Returns

The output destination of the formatter.

Throws

FormatterClosedException	If the formatter has been closed.

public String toString ()

Returns the content by calling the toString() method of the output destination.

Returns

The content by calling the toString() method of the output destination.

Throws

FormatterClosedException	If the formatter has been closed.

Jan	FEB	Mar
	18
2008	2009	2010

Interfaces

Classes

Enums

Exceptions

Formatter

Class Overview

Summary

Public Constructors

public Formatter ()

public Formatter (Appendable a)

Parameters

public Formatter (Locale l)

Parameters

public Formatter (Appendable a, Locale l)

Parameters

public Formatter (String fileName)

Parameters

Throws

public Formatter (String fileName, String csn)

Parameters

Throws

public Formatter (String fileName, String csn, Locale l)

Parameters

Throws

public Formatter (File file)

Parameters

Throws

public Formatter (File file, String csn)

Parameters

Throws

public Formatter (File file, String csn, Locale l)

Parameters

Throws

public Formatter (OutputStream os)

Parameters

public Formatter (OutputStream os, String csn)

Parameters

Throws

public Formatter (OutputStream os, String csn, Locale l)

Parameters

Throws

public Formatter (PrintStream ps)

Parameters

Public Methods

public void close ()

public void flush ()

Throws

public Formatter format (Locale l, String format, Object... args)

Parameters

Returns

Throws

public Formatter format (String format, Object... args)

Parameters

Returns

Throws

public IOException ioException ()

Returns

public Locale locale ()

Returns

Throws

public Appendable out ()

Returns

Throws

public String toString ()

Returns

Throws