java.lang.Objectjava.util.Formatter
public final class Formatter
An interpreter for printf-style format strings. This class provides support for layout justification and alignment, common formats for numeric, string, and date/time data, and locale-specific output. Common Java types such as byte , BigDecimal , and Calendar are supported. Limited formatting customization for arbitrary user types is provided through the Formattable interface.
Formatters are not necessarily safe for multithreaded access. Thread safety is optional and is the responsibility of users of methods in this class.
Formatted printing for the Java language is heavily inspired by C's printf . Although the format strings are similar to C, some customizations have been made to accommodate the Java language and exploit some of its features. Also, Java formatting is more strict than C's; for example, if a conversion is incompatible with a flag, an exception will be thrown. In C inapplicable flags are silently ignored. The format strings are thus intended to be recognizable to C programmers but not necessarily completely compatible with those in C.
Examples of expected usage:
StringBuilder sb = new StringBuilder(); // Send all output to the Appendable object sb Formatter formatter = new Formatter(sb, Locale.US); // Explicit argument indices may be used to re-order output. formatter.format("%4$2s %3$2s %2$2s %1$2s", "a", "b", "c", "d") //->
->" d c b a" // Optional locale as the first argument can be used to get // locale-specific formatting of numbers. The precision and width can be // given to round and align the value. formatter.format(Locale.FRANCE, "e = %+10.4f", Math.E); //->
->"e = +2,7183" // The '(' numeric flag may be used to format negative numbers with // parentheses rather than a minus sign. Group separators are // automatically inserted. formatter.format("Amount gained or lost since last statement: $ %(,.2f", balanceDelta); //->
->"Amount gained or lost since last statement: $ (6,217.58)"
Convenience methods for common formatting requests exist as illustrated by the following invocations:
// Writes a formatted string to System.out. System.out.format("Local time: %tT", Calendar.getInstance()); //->
->"Local time: 13:34:18" // Writes formatted output to System.err. System.err.printf("Unable to open file '%1$s': %2$s", fileName, exception.getMessage()); //->
->"Unable to open file 'food': No such file or directory"
Like C's sprintf(3) , Strings may be formatted using the static method String.format :
// Format a string containing a date. import java.util.Calendar; import java.util.GregorianCalendar; import static java.util.Calendar.*; Calendar c = new GregorianCalendar(1995, MAY, 23); String s = String.format("Duke's Birthday: %1$tm %1$te,%1$tY", c); //->
->s == "Duke's Birthday: May 23, 1995"
This specification is divided into two sections. The first section, Summary , covers the basic formatting concepts. This section is intended for users who want to get started quickly and are familiar with formatted printing in other programming languages. The second section, Details , covers the specific implementation details. It is intended for users who want more precise specification of formatting behavior.
This section is intended to provide a brief overview of formatting concepts. For precise behavioral details, refer to the Details section.
Every method which produces formatted output requires a format string and an argument list . The format string is a String which may contain fixed text and one or more embedded format specifiers . Consider the following example:
This format string is the first argument to the format method. It contains three format specifiers " %1$tm ", " %1$te ", and " %1$tY " which indicate how the arguments should be processed and where they should be inserted in the text. The remaining portions of the format string are fixed text including "Dukes Birthday: " and any other spaces or punctuation. The argument list consists of all arguments passed to the method after the format string. In the above example, the argument list is of size one and consists of the Calendar object c .Calendar c = ...; String s = String.format("Duke's Birthday: %1$tm %1$te,%1$tY", c);
%[argument_index$][flags][width][.precision]conversion
The optional argument_index is a decimal integer indicating the position of the argument in the argument list. The first argument is referenced by " 1$ ", the second by " 2$ ", etc.
The optional flags is a set of characters that modify the output format. The set of valid flags depends on the conversion.
The optional width is a non-negative decimal integer indicating the minimum number of characters to be written to the output.
The optional precision is a non-negative decimal integer usually used to restrict the number of characters. The specific behavior depends on the conversion.
The required conversion is a character indicating how the argument should be formatted. The set of valid conversions for a given argument depends on the argument's data type.
%[argument_index$][flags][width]conversion
The optional argument_index , flags and width are defined as above.
The required conversion is a two character sequence. The first character is 't' or 'T' . The second character indicates the format to be used. These characters are similar to but not completely identical to those defined by GNU date and POSIX strftime(3c) .
%[flags][width]conversion
The optional flags and width is defined as above.
The required conversion is a character indicating content to be inserted in the output.
Conversions are divided into the following categories:
The following table summarizes the supported conversions. Conversions denoted by an upper-case character (i.e. 'B' , 'H' , 'S' , 'C' , 'X' , 'E' , 'G' , 'A' , and 'T' ) are the same as those for the corresponding lower-case conversion characters except that the result is converted to upper case according to the rules of the prevailing Locale . The result is equivalent to the following invocation of String.toUpperCase()
out.toUpperCase()
Conversion | Argument Category | Description |
---|---|---|
'b' , 'B' | general | If the argument arg is null , then the result is " false ". If arg is a boolean or Boolean , then the result is the string returned by String.valueOf() . Otherwise, the result is "true". |
'h' , 'H' | general | If the argument arg is null , then the result is " null ". Otherwise, the result is obtained by invoking Integer.toHexString(arg.hashCode()) . |
's' , 'S' | general | If the argument arg is null , then the result is " null ". If arg implements Formattable , then arg.formatTo is invoked. Otherwise, the result is obtained by invoking arg.toString() . |
'c' , 'C' | character | The result is a Unicode character |
'd' | integral | The result is formatted as a decimal integer |
'o' | integral | The result is formatted as an octal integer |
'x' , 'X' | integral | The result is formatted as a hexadecimal integer |
'e' , 'E' | floating point | The result is formatted as a decimal number in computerized scientific notation |
'f' | floating point | The result is formatted as a decimal number |
'g' , 'G' | floating point | The result is formatted using computerized scientific notation or decimal format, depending on the precision and the value after rounding. |
'a' , 'A' | floating point | The result is formatted as a hexadecimal floating-point number with a significand and an exponent |
't' , 'T' | date/time | Prefix for date and time conversion characters. See Date/Time Conversions . |
'%' | percent | The result is a literal '%' ( '\u0025' ) |
'n' | line separator | The result is the platform-specific line separator |
Any characters not explicitly defined as conversions are illegal and are reserved for future extensions.
The following date and time conversion suffix characters are defined for the 't' and 'T' conversions. The types are similar to but not completely identical to those defined by GNU date and POSIX strftime(3c) . Additional conversion types are provided to access Java-specific functionality (e.g. 'L' for milliseconds within the second).
The following conversion characters are used for formatting times:
'H' | Hour of the day for the 24-hour clock, formatted as two digits with a leading zero as necessary i.e. 00 - 23 . |
'I' | Hour for the 12-hour clock, formatted as two digits with a leading zero as necessary, i.e. 01 - 12 . |
'k' | Hour of the day for the 24-hour clock, i.e. 0 - 23 . |
'l' | Hour for the 12-hour clock, i.e. 1 - 12 . |
'M' | Minute within the hour formatted as two digits with a leading zero as necessary, i.e. 00 - 59 . |
'S' | Seconds within the minute, formatted as two digits with a leading zero as necessary, i.e. 00 - 60 (" 60 " is a special value required to support leap seconds). |
'L' | Millisecond within the second formatted as three digits with leading zeros as necessary, i.e. 000 - 999 . |
'N' | Nanosecond within the second, formatted as nine digits with leading zeros as necessary, i.e. 000000000 - 999999999 . |
'p' | Locale-specific morning or afternoon marker in lower case, e.g." am " or " pm ". Use of the conversion prefix 'T' forces this output to upper case. |
'z' | RFC 822 style numeric time zone offset from GMT, e.g. -0800 . |
'Z' | A string representing the abbreviation for the time zone. The Formatter's locale will supersede the locale of the argument (if any). |
's' | Seconds since the beginning of the epoch starting at 1 January 1970 00:00:00 UTC, i.e. Long.MIN_VALUE/1000 to Long.MAX_VALUE/1000 . |
'Q' | Milliseconds since the beginning of the epoch starting at 1 January 1970 00:00:00 UTC, i.e. Long.MIN_VALUE to Long.MAX_VALUE . |
The following conversion characters are used for formatting dates:
'B' | Locale-specific full month name , e.g. "January" , "February" . |
'b' | Locale-specific abbreviated month name , e.g. "Jan" , "Feb" . |
'h' | Same as 'b' . |
'A' | Locale-specific full name of the day of the week , e.g. "Sunday" , "Monday" |
'a' | Locale-specific short name of the day of the week , e.g. "Sun" , "Mon" |
'C' | Four-digit year divided by 100 , formatted as two digits with leading zero as necessary, i.e. 00 - 99 |
'Y' | Year, formatted as at least four digits with leading zeros as necessary, e.g. 0092 equals 92 CE for the Gregorian calendar. |
'y' | Last two digits of the year, formatted with leading zeros as necessary, i.e. 00 - 99 . |
'j' | Day of year, formatted as three digits with leading zeros as necessary, e.g. 001 - 366 for the Gregorian calendar. |
'm' | Month, formatted as two digits with leading zeros as necessary, i.e. 01 - 13 . |
'd' | Day of month, formatted as two digits with leading zeros as necessary, i.e. 01 - 31 |
'e' | Day of month, formatted as two digits, i.e. 1 - 31 . |
The following conversion characters are used for formatting common date/time compositions.
'R' | Time formatted for the 24-hour clock as "%tH:%tM" |
'T' | Time formatted for the 24-hour clock as "%tH:%tM:%tS" . |
'r' | Time formatted for the 12-hour clock as "%tI:%tM:%tS %Tp" . The location of the morning or afternoon marker ( '%Tp' ) may be locale-dependent. |
'D' | Date formatted as "%tm/%td/%ty" . |
'F' | ISO 8601 complete date formatted as "%tY-%tm-%td" . |
'c' | Date and time formatted as "%ta %tb %td %tT %tZ %tY" , e.g. "Sun Jul 20 16:17:00 EDT 1969" . |
Any characters not explicitly defined as date/time conversion suffixes are illegal and are reserved for future extensions.
The following table summarizes the supported flags. y means the flag is supported for the indicated argument types.
Flag | General | Character | Integral | Floating Point | Date/Time | Description |
---|---|---|---|---|---|---|
'-' | y | y | y | y | y | The result will be left-justified. |
'#' | y 1 | - | y 3 | y | - | The result should use a conversion-dependent alternate form |
'+' | - | - | y 4 | y | - | The result will always include a sign |
' ' | - | - | y 4 | y | - | The result will include a leading space for positive values |
'0' | - | - | y | y | - | The result will be zero-padded |
',' | - | - | y 2 | y 5 | - | The result will include locale-specific grouping separators |
'(' | - | - | y 4 | y 5 | - | The result will enclose negative numbers in parentheses |
1 Depends on the definition of Formattable .
2 For 'd' conversion only.
3 For 'o' , 'x' , and 'X' conversions only.
4 For 'd' , 'o' , 'x' , and 'X' conversions applied to BigInteger or 'd' applied to byte , Byte , short , Short , int and Integer , long , and Long .
5 For 'e' , 'E' , 'f' , 'g' , and 'G' conversions only.
Any characters not explicitly defined as flags are illegal and are reserved for future extensions.
The width is the minimum number of characters to be written to the output. For the line separator conversion, width is not applicable; if it is provided, an exception will be thrown.
For general argument types, the precision is the maximum number of characters to be written to the output.
For the floating-point conversions 'e' , 'E' , and 'f' the precision is the number of digits after the decimal separator. If the conversion is 'g' or 'G' , then the precision is the total number of digits in the resulting magnitude after rounding. If the conversion is 'a' or 'A' , then the precision must not be specified.
For character, integral, and date/time argument types and the percent and line separator conversions, the precision is not applicable; if a precision is provided, an exception will be thrown.
The argument index is a decimal integer indicating the position of the argument in the argument list. The first argument is referenced by " 1$ ", the second by " 2$ ", etc.
Another way to reference arguments by position is to use the
'<'
'<'
(
'\u003c'
) flag, which causes the argument for the previous format specifier to be re-used. For example, the following two statements would produce identical strings:
Calendar c = ...; String s1 = String.format("Duke's Birthday: %1$tm %1$te,%1$tY", c); String s2 = String.format("Duke's Birthday: %1$tm%<te,%<tY", c);
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This section is intended to provide behavioral details for formatting, including conditions and exceptions, supported data types, localization, and interactions between flags, conversions, and data types. For an overview of formatting concepts, refer to the Summary
Any characters not explicitly defined as conversions, date/time conversion suffixes, or flags are illegal and are reserved for future extensions. Use of such a character in a format string will cause an UnknownFormatConversionException or UnknownFormatFlagsException to be thrown.
If the format specifier contains a width or precision with an invalid value or which is otherwise unsupported, then a IllegalFormatWidthException or IllegalFormatPrecisionException respectively will be thrown.
If a format specifier contains a conversion character that is not applicable to the corresponding argument, then an IllegalFormatConversionException will be thrown.
All specified exceptions may be thrown by any of the format methods of Formatter as well as by any format convenience methods such as String.format and PrintStream.printf .
Conversions denoted by an upper-case character (i.e. 'B' , 'H' , 'S' , 'C' , 'X' , 'E' , 'G' , 'A' , and 'T' ) are the same as those for the corresponding lower-case conversion characters except that the result is converted to upper case according to the rules of the prevailing Locale . The result is equivalent to the following invocation of String.toUpperCase()
out.toUpperCase()
The following general conversions may be applied to any argument type:
'b' | '\u0062' |
Produces either "
true
" or "
false
" as returned by
Boolean.toString(boolean)
. If the argument is null , then the result is " false ". If the argument is a boolean or Boolean , then the result is the string returned by String.valueOf() . Otherwise, the result is " true ". If the '#' flag is given, then a FormatFlagsConversionMismatchException will be thrown. |
'B' | '\u0042' | The upper-case variant of 'b' . |
'h' | '\u0068' |
Produces a string representing the hash code value of the object. If the argument, arg is null , then the result is " null ". Otherwise, the result is obtained by invoking Integer.toHexString(arg.hashCode()) . If the '#' flag is given, then a FormatFlagsConversionMismatchException will be thrown. |
'H' | '\u0048' | The upper-case variant of 'h' . |
's' | '\u0073' |
Produces a string. If the argument is null , then the result is " null ". If the argument implements Formattable , then its formatTo method is invoked. Otherwise, the result is obtained by invoking the argument's toString() method. If the '#' flag is given and the argument is not a Formattable , then a FormatFlagsConversionMismatchException will be thrown. |
'S' | '\u0053' | The upper-case variant of 's' . |
After digits are obtained for the integer part, fractional part, and exponent (as appropriate for the data type), the following transformation is applied:
The following conversions may be applied to
float
,
Float
The following conversions may be applied
BigDecimal
The
format
method for this object which has a locale argument does not change this value.
An invocation of this method behaves in exactly the same way as the invocation
Depending on the specification of
toString
for the
Appendable
, the returned string may or may not contain the characters written to the destination. For instance, buffers typically return their contents in
toString()
, but streams cannot since the data is discarded.
Flushing a formatter writes any buffered output in the destination to the underlying stream.
Closing a formatter allows it to release resources it may be holding (such as open files). If the formatter is already closed, then invoking this method has no effect.
Attempting to invoke any methods except
ioException()
in this formatter after it has been closed will result in a
FormatterClosedException
.
If the destination's
append()
method never throws
IOException
, then this method will always return
null
.
The following
flags
The following flags apply to general conversions:
apply to general conversions:
'-'
'\u002d'
Left justifies the output. Spaces (
'\u0020'
) will be added at the end of the converted value as required to fill the minimum width of the field. If the width is not provided, then a
MissingFormatWidthException
will be thrown. If this flag is not given then the output will be right-justified.
'#'
'\u0023'
Requires the output use an alternate form. The definition of the form is specified by the conversion.
The width is the minimum number of characters to be written to the output.
' '
(
\u0020'
) until the total number of characters equals the width. The padding is on the left by default.
'-'
flag is given, then the padding will be on the right. If the width is not specified then there is no minimum.
The precision is the maximum number of characters to be written to the output.
precision
characters even if the width is greater than the precision. If the precision is not specified then there is no explicit limit on the number of characters.
Character
char
,
Character
byte
,
Byte
short
, and
Short
.
int
and
Integer
when
Character.isValidCodePoint(int)
true
.
false
then an
IllegalFormatCodePointException
will be thrown.
'c'
'\u0063'
Formats the argument as a Unicode character as described in
Unicode Character Representation
.
char
in the case where the argument represents a supplementary character.
If the
'#'
flag is given, then a
FormatFlagsConversionMismatchException
will be thrown.
'C'
'\u0043'
The upper-case variant of
'c'
.
The
'-'
flag defined for
General conversions
applies.
'#'
flag is given, then a
FormatFlagsConversionMismatchException
will be thrown.
The width is defined as for
General conversions
.
The precision is not applicable. If the precision is specified then an
IllegalFormatPrecisionException
will be thrown.
Numeric
Numeric conversions are divided into the following categories:
Numeric types will be formatted according to the following algorithm:
z
; that is
d -
'0'
+ z
.
If a decimal separator is present, a locale-specific
decimal separator
is substituted.
','
(
'\u002c'
) flag is given, then the locale-specific
grouping separator
is inserted by scanning the integer part of the string from least significant to most significant digits and inserting a separator at intervals defined by the locale's
grouping size
.
If the
'0'
flag is given, then the locale-specific
zero digits
are inserted after the sign character, if any, and before the first non-zero digit, until the length of the string is equal to the requested field width.
If the value is negative and the
'('
flag is given, then a
'('
(
'\u0028'
) is prepended and a
')'
(
'\u0029'
) is appended.
If the value is negative (or floating-point negative zero) and
'('
flag is not given, then a
'-'
(
'\u002d'
) is prepended.
If the
'+'
flag is given and the value is positive or zero (or floating-point positive zero), then a
'+'
(
'\u002b'
) will be prepended.
If the value is NaN or positive infinity the literal strings "NaN" or "Infinity" respectively, will be output.
'('
flag is given otherwise the output will be "-Infinity". These values are not localized.
Byte, Short, Integer, and Long
The following conversions may be applied to
byte
,
Byte
short
,
Short
int
and
Integer
long
, and
Long
.
'd'
'\u0054'
Formats the argument as a decimal integer. The
localization algorithm
is applied.
If the
'0'
flag is given and the value is negative, then the zero padding will occur after the sign.
If the
'#'
flag is given then a
FormatFlagsConversionMismatchException
will be thrown.
'o'
'\u006f'
Formats the argument as an integer in base eight. No localization is applied.
If
x
is negative then the result will be an unsigned value generated by adding 2
n
to the value where
n
is the number of bits in the type as returned by the static
SIZE
field in the
Byte
,
Short
,
Integer
, or
Long
classes as appropriate.
If the
'#'
flag is given then the output will always begin with the radix indicator
'0'
.
If the
'0'
flag is given then the output will be padded with leading zeros to the field width following any indication of sign.
If
'('
,
'+'
, '  ', or
','
flags are given then a
FormatFlagsConversionMismatchException
will be thrown.
'x'
'\u0078'
Formats the argument as an integer in base sixteen. No localization is applied.
If
x
is negative then the result will be an unsigned value generated by adding 2
n
to the value where
n
is the number of bits in the type as returned by the static
SIZE
field in the
Byte
,
Short
,
Integer
, or
Long
classes as appropriate.
If the
'#'
flag is given then the output will always begin with the radix indicator
"0x"
.
If the
'0'
flag is given then the output will be padded to the field width with leading zeros after the radix indicator or sign (if present).
If
'('
,
' '
,
'+'
, or
','
flags are given then a
FormatFlagsConversionMismatchException
will be thrown.
'X'
'\u0058'
The upper-case variant of
'x'
. The entire string representing the number will be converted to
upper case
'x'
(if any) and all hexadecimal digits
'a'
-
'f'
(
'\u0061'
-
'\u0066'
).
If the conversion is
'o'
,
'x'
, or
'X'
and both the
'#'
and the
'0'
flags are given, then result will contain the radix indicator (
'0'
for octal and
"0x"
or
"0X"
for hexadecimal), some number of zeros (based on the width), and the value.
If the
'-'
flag is not given, then the space padding will occur before the sign.
The following flags apply to numeric integral conversions:
'+'
'\u002b'
Requires the output to include a positive sign for all positive numbers. If this flag is not given then only negative values will include a sign.
If both the
'+'
and
' '
flags are given then an
IllegalFormatFlagsException
will be thrown.
' '
'\u0020'
Requires the output to include a single extra space (
'\u0020'
) for non-negative values.
If both the
'+'
and
' '
flags are given then an
IllegalFormatFlagsException
will be thrown.
'0'
'\u0030'
Requires the output to be padded with leading
zeros
to the minimum field width following any sign or radix indicator except when converting NaN or infinity. If the width is not provided, then a
MissingFormatWidthException
will be thrown.
If both the
'-'
and
'0'
flags are given then an
IllegalFormatFlagsException
will be thrown.
','
'\u002c'
Requires the output to include the locale-specific
group separators
as described in the
"group" section
of the localization algorithm.
'('
'\u0028'
Requires the output to prepend a
'('
(
'\u0028'
) and append a
')'
(
'\u0029'
) to negative values.
If no flags are given the default formatting is as follows:
The output is right-justified within the
width
Negative numbers begin with a
'-'
(
'\u002d'
)
Positive numbers and zero do not include a sign or extra leading space
No grouping separators are included
The width is the minimum number of characters to be written to the output. This includes any signs, digits, grouping separators, radix indicator, and parentheses.
'\u0020'
) until the total number of characters equals width. The padding is on the left by default.
'-'
flag is given then the padding will be on the right. If width is not specified then there is no minimum.
The precision is not applicable. If precision is specified then an
IllegalFormatPrecisionException
will be thrown.
The following conversions may be applied to
BigInteger
.
'd'
'\u0054'
Requires the output to be formatted as a decimal integer. The
localization algorithm
is applied.
If the
'#'
flag is given
FormatFlagsConversionMismatchException
will be thrown.
'o'
'\u006f'
Requires the output to be formatted as an integer in base eight. No localization is applied.
If
x
is negative then the result will be a signed value beginning with
'-'
(
'\u002d'
). Signed output is allowed for this type because unlike the primitive types it is not possible to create an unsigned equivalent without assuming an explicit data-type size.
If
x
is positive or zero and the
'+'
flag is given then the result will begin with
'+'
(
'\u002b'
).
If the
'#'
flag is given then the output will always begin with
'0'
prefix.
If the
'0'
flag is given then the output will be padded with leading zeros to the field width following any indication of sign.
If the
','
flag is given then a
FormatFlagsConversionMismatchException
will be thrown.
'x'
'\u0078'
Requires the output to be formatted as an integer in base sixteen. No localization is applied.
If
x
is negative then the result will be a signed value beginning with
'-'
(
'\u002d'
). Signed output is allowed for this type because unlike the primitive types it is not possible to create an unsigned equivalent without assuming an explicit data-type size.
If
x
is positive or zero and the
'+'
flag is given then the result will begin with
'+'
(
'\u002b'
).
If the
'#'
flag is given then the output will always begin with the radix indicator
"0x"
.
If the
'0'
flag is given then the output will be padded to the field width with leading zeros after the radix indicator or sign (if present).
If the
','
flag is given then a
FormatFlagsConversionMismatchException
will be thrown.
'X'
'\u0058'
The upper-case variant of
'x'
. The entire string representing the number will be converted to
upper case
'x'
(if any) and all hexadecimal digits
'a'
-
'f'
(
'\u0061'
-
'\u0066'
).
If the conversion is
'o'
,
'x'
, or
'X'
and both the
'#'
and the
'0'
flags are given, then result will contain the base indicator (
'0'
for octal and
"0x"
or
"0X"
for hexadecimal), some number of zeros (based on the width), and the value.
If the
'0'
flag is given and the value is negative, then the zero padding will occur after the sign.
If the
'-'
flag is not given, then the space padding will occur before the sign.
All
flags
defined for Byte, Short, Integer, and Long apply. The
default behavior
when no flags are given is the same as for Byte, Short, Integer, and Long.
The specification of
width
is the same as defined for Byte, Short, Integer, and Long.
The precision is not applicable. If precision is specified then an
IllegalFormatPrecisionException
will be thrown.
Float and Double
double
and
Double
.
'e'
'\u0065'
Requires the output to be formatted using
computerized scientific notation
. The
localization algorithm
is applied.
The formatting of the magnitude
m
depends upon its value.
If
m
is NaN or infinite, the literal strings "NaN" or "Infinity", respectively, will be output. These values are not localized.
If
m
is positive-zero or negative-zero, then the exponent will be
"+00"
.
Otherwise, the result is a string that represents the sign and magnitude (absolute value) of the argument. The formatting of the sign is described in the
localization algorithm
.
m
depends upon its value.
Let
n
be the unique integer such that 10
n
<=
m
< 10
n
+1
; then let
a
be the mathematically exact quotient of
m
and 10
n
so that 1 <=
a
< 10.
a
, as a single decimal digit, followed by the decimal separator followed by decimal digits representing the fractional part of
a
, followed by the exponent symbol
'e'
(
'\u0065'
), followed by the sign of the exponent, followed by a representation of
n
as a decimal integer, as produced by the method
Long.toString(long, int)
, and zero-padded to include at least two digits.
The number of digits in the result for the fractional part of
m
or
a
is equal to the precision.
6
. If the precision is less than the number of digits which would appear after the decimal point in the string returned by
Float.toString(float)
or
Double.toString(double)
respectively, then the value will be rounded using the
round half up algorithm
. Otherwise, zeros may be appended to reach the precision. For a canonical representation of the value, use
Float.toString(float)
or
Double.toString(double)
as appropriate.
If the
','
flag is given, then an
FormatFlagsConversionMismatchException
will be thrown.
'E'
'\u0045'
The upper-case variant of
'e'
.
'E'
(
'\u0045'
).
'g'
'\u0067'
Requires the output to be formatted in general scientific notation as described below. The
localization algorithm
is applied.
After rounding for the precision, the formatting of the resulting magnitude
m
depends on its value.
If
m
is greater than or equal to 10
-4
but less than 10
precision
then it is represented in
decimal format
.
If
m
is less than 10
-4
or greater than or equal to 10
precision
, then it is represented in
computerized scientific notation
.
The total number of significant digits in
m
is equal to the precision.
6
.
0
, then it is taken to be
1
.
If the
'#'
flag is given then an
FormatFlagsConversionMismatchException
will be thrown.
'G'
'\u0047'
The upper-case variant of
'g'
.
'f'
'\u0066'
Requires the output to be formatted using
decimal format
. The
localization algorithm
is applied.
The result is a string that represents the sign and magnitude (absolute value) of the argument. The formatting of the sign is described in the
localization algorithm
.
m
depends upon its value.
If
m
NaN or infinite, the literal strings "NaN" or "Infinity", respectively, will be output. These values are not localized.
The magnitude is formatted as the integer part of
m
, with no leading zeroes, followed by the decimal separator followed by one or more decimal digits representing the fractional part of
m
.
The number of digits in the result for the fractional part of
m
or
a
is equal to the precision.
6
. If the precision is less than the number of digits which would appear after the decimal point in the string returned by
Float.toString(float)
or
Double.toString(double)
respectively, then the value will be rounded using the
round half up algorithm
. Otherwise, zeros may be appended to reach the precision. For a canonical representation of the value,use
Float.toString(float)
or
Double.toString(double)
as appropriate.
'a'
'\u0061'
Requires the output to be formatted in hexadecimal exponential form. No localization is applied.
The result is a string that represents the sign and magnitude (absolute value) of the argument
x
.
If
x
is negative or a negative-zero value then the result will begin with
'-'
(
'\u002d'
).
If
x
is positive or a positive-zero value and the
'+'
flag is given then the result will begin with
'+'
(
'\u002b'
).
The formatting of the magnitude
m
depends upon its value.
If the value is NaN or infinite, the literal strings "NaN" or "Infinity", respectively, will be output.
If
m
is zero then it is represented by the string
"0x0.0p0"
.
If
m
is a
double
value with a normalized representation then substrings are used to represent the significand and exponent fields.
"0x1."
followed by the hexadecimal representation of the rest of the significand as a fraction.
'p'
(
'\u0070'
) followed by a decimal string of the unbiased exponent as if produced by invoking
Integer.toString
on the exponent value.
If
m
is a
double
value with a subnormal representation then the significand is represented by the characters
'0x0.'
followed by the hexadecimal representation of the rest of the significand as a fraction.
'p-1022'
. Note that there must be at least one nonzero digit in a subnormal significand.
If the
'('
or
','
flags are given, then a
FormatFlagsConversionMismatchException
will be thrown.
'A'
'\u0041'
The upper-case variant of
'a'
.
'x'
(
'\u0078'
) and
'p'
(
'\u0070'
and all hexadecimal digits
'a'
-
'f'
(
'\u0061'
-
'\u0066'
).
All
flags
defined for Byte, Short, Integer, and Long apply.
If the
'#'
flag is given, then the decimal separator will always be present.
If no flags are given the default formatting is as follows:
The output is right-justified within the
width
Negative numbers begin with a
'-'
Positive numbers and positive zero do not include a sign or extra leading space
No grouping separators are included
The decimal separator will only appear if a digit follows it
The width is the minimum number of characters to be written to the output. This includes any signs, digits, grouping separators, decimal separators, exponential symbol, radix indicator, parentheses, and strings representing infinity and NaN as applicable.
'\u0020'
) until the total number of characters equals width. The padding is on the left by default.
'-'
flag is given then the padding will be on the right. If width is not specified then there is no minimum.
If the conversion is
'e'
,
'E'
or
'f'
, then the precision is the number of digits after the decimal separator.
6
.
If the conversion is
'g'
or
'G'
, then the precision is the total number of significant digits in the resulting magnitude after rounding.
6
.
0
, then it is taken to be
1
.
If the conversion is
'a'
or
'A'
, then the precision is the number of hexadecimal digits after the decimal separator. If the precision is not provided, then all of the digits as returned by
Double.toHexString(double)
will be output.
BigDecimal
.
'e'
'\u0065'
Requires the output to be formatted using
computerized scientific notation
. The
localization algorithm
is applied.
The formatting of the magnitude
m
depends upon its value.
If
m
is positive-zero or negative-zero, then the exponent will be
"+00"
.
Otherwise, the result is a string that represents the sign and magnitude (absolute value) of the argument. The formatting of the sign is described in the
localization algorithm
.
m
depends upon its value.
Let
n
be the unique integer such that 10
n
<=
m
< 10
n
+1
; then let
a
be the mathematically exact quotient of
m
and 10
n
so that 1 <=
a
< 10.
a
, as a single decimal digit, followed by the decimal separator followed by decimal digits representing the fractional part of
a
, followed by the exponent symbol
'e'
(
'\u0065'
), followed by the sign of the exponent, followed by a representation of
n
as a decimal integer, as produced by the method
Long.toString(long, int)
, and zero-padded to include at least two digits.
The number of digits in the result for the fractional part of
m
or
a
is equal to the precision.
6
. If the precision is less than the number of digits which would appear after the decimal point in the string returned by
Float.toString(float)
or
Double.toString(double)
respectively, then the value will be rounded using the
round half up algorithm
. Otherwise, zeros may be appended to reach the precision. For a canonical representation of the value, use
BigDecimal.toString()
.
If the
','
flag is given, then an
FormatFlagsConversionMismatchException
will be thrown.
'E'
'\u0045'
The upper-case variant of
'e'
.
'E'
(
'\u0045'
).
'g'
'\u0067'
Requires the output to be formatted in general scientific notation as described below. The
localization algorithm
is applied.
After rounding for the precision, the formatting of the resulting magnitude
m
depends on its value.
If
m
is greater than or equal to 10
-4
but less than 10
precision
then it is represented in
decimal format
.
If
m
is less than 10
-4
or greater than or equal to 10
precision
, then it is represented in
computerized scientific notation
.
The total number of significant digits in
m
is equal to the precision.
6
.
0
, then it is taken to be
1
.
If the
'#'
flag is given then an
FormatFlagsConversionMismatchException
will be thrown.
'G'
'\u0047'
The upper-case variant of
'g'
.
'f'
'\u0066'
Requires the output to be formatted using
decimal format
. The
localization algorithm
is applied.
The result is a string that represents the sign and magnitude (absolute value) of the argument. The formatting of the sign is described in the
localization algorithm
.
m
depends upon its value.
The magnitude is formatted as the integer part of
m
, with no leading zeroes, followed by the decimal separator followed by one or more decimal digits representing the fractional part of
m
.
The number of digits in the result for the fractional part of
m
or
a
is equal to the precision.
6
. If the precision is less than the number of digits which would appear after the decimal point in the string returned by
Float.toString(float)
or
Double.toString(double)
respectively, then the value will be rounded using the
round half up algorithm
. Otherwise, zeros may be appended to reach the precision. For a canonical representation of the value, use
BigDecimal.toString()
.
All
flags
defined for Byte, Short, Integer, and Long apply.
If the
'#'
flag is given, then the decimal separator will always be present.
The
default behavior
when no flags are given is the same as for Float and Double.
The specification of
width
and
precision
is the same as defined for Float and Double.
Date/Time
This conversion may be applied to
long
,
Long
,
Calendar
, and
Date
.
't'
'\u0074'
Prefix for date and time conversion characters.
'T'
'\u0054'
The upper-case variant of
't'
.
The following date and time conversion character suffixes are defined for the
't'
and
'T'
conversions.
date
and POSIX
strftime(3c)
. Additional conversion types are provided to access Java-specific functionality (e.g.
'L'
for milliseconds within the second).
The following conversion characters are used for formatting times:
'H'
'\u0048'
Hour of the day for the 24-hour clock, formatted as two digits with a leading zero as necessary i.e.
00 - 23
.
00
corresponds to midnight.
'I'
'\u0049'
Hour for the 12-hour clock, formatted as two digits with a leading zero as necessary, i.e.
01 - 12
.
01
corresponds to one o'clock (either morning or afternoon).
'k'
'\u006b'
Hour of the day for the 24-hour clock, i.e.
0 - 23
.
0
corresponds to midnight.
'l'
'\u006c'
Hour for the 12-hour clock, i.e.
1 - 12
.
1
corresponds to one o'clock (either morning or afternoon).
'M'
'\u004d'
Minute within the hour formatted as two digits with a leading zero as necessary, i.e.
00 - 59
.
'S'
'\u0053'
Seconds within the minute, formatted as two digits with a leading zero as necessary, i.e.
00 - 60
("
60
" is a special value required to support leap seconds).
'L'
'\u004c'
Millisecond within the second formatted as three digits with leading zeros as necessary, i.e.
000 - 999
.
'N'
'\u004e'
Nanosecond within the second, formatted as nine digits with leading zeros as necessary, i.e.
000000000 - 999999999
. The precision of this value is limited by the resolution of the underlying operating system or hardware.
'p'
'\u0070'
Locale-specific
morning or afternoon
am
" or "
pm
".
'T'
forces this output to upper case.
'p'
produces lower-case output.
date
and POSIX
strftime(3c)
which produce upper-case output.)
'z'
'\u007a'
RFC 822
style numeric time zone offset from GMT, e.g.
-0800
.
'Z'
'\u005a'
A string representing the abbreviation for the time zone.
's'
'\u0073'
Seconds since the beginning of the epoch starting at 1 January 1970
00:00:00
UTC, i.e.
Long.MIN_VALUE/1000
to
Long.MAX_VALUE/1000
.
'Q'
'\u004f'
Milliseconds since the beginning of the epoch starting at 1 January 1970
00:00:00
UTC, i.e.
Long.MIN_VALUE
to
Long.MAX_VALUE
. The precision of this value is limited by the resolution of the underlying operating system or hardware.
The following conversion characters are used for formatting dates:
'B'
'\u0042'
Locale-specific
full month name
, e.g.
"January"
,
"February"
.
'b'
'\u0062'
Locale-specific
abbreviated month name
, e.g.
"Jan"
,
"Feb"
.
'h'
'\u0068'
Same as
'b'
.
'A'
'\u0041'
Locale-specific full name of the
day of the week
, e.g.
"Sunday"
,
"Monday"
'a'
'\u0061'
Locale-specific short name of the
day of the week
, e.g.
"Sun"
,
"Mon"
'C'
'\u0043'
Four-digit year divided by
100
, formatted as two digits with leading zero as necessary, i.e.
00 - 99
'Y'
'\u0059'
Year, formatted to at least four digits with leading zeros as necessary, e.g.
0092
equals
92
CE for the Gregorian calendar.
'y'
'\u0079'
Last two digits of the year, formatted with leading zeros as necessary, i.e.
00 - 99
.
'j'
'\u006a'
Day of year, formatted as three digits with leading zeros as necessary, e.g.
001 - 366
for the Gregorian calendar.
001
corresponds to the first day of the year.
'm'
'\u006d'
Month, formatted as two digits with leading zeros as necessary, i.e.
01 - 13
, where "
01
" is the first month of the year and ("
13
" is a special value required to support lunar calendars).
'd'
'\u0064'
Day of month, formatted as two digits with leading zeros as necessary, i.e.
01 - 31
, where "
01
" is the first day of the month.
'e'
'\u0065'
Day of month, formatted as two digits, i.e.
1 - 31
where "
1
" is the first day of the month.
The following conversion characters are used for formatting common date/time compositions.
'R'
'\u0052'
Time formatted for the 24-hour clock as
"%tH:%tM"
'T'
'\u0054'
Time formatted for the 24-hour clock as
"%tH:%tM:%tS"
.
'r'
'\u0072'
Time formatted for the 12-hour clock as
"%tI:%tM:%tS %Tp"
.
'%Tp'
) may be locale-dependent.
'D'
'\u0044'
Date formatted as
"%tm/%td/%ty"
.
'F'
'\u0046'
ISO 8601
"%tY-%tm-%td"
.
'c'
'\u0063'
Date and time formatted as
"%ta %tb %td %tT %tZ %tY"
, e.g.
"Sun Jul 20 16:17:00 EDT 1969"
.
The
'-'
flag defined for
General conversions
applies.
'#'
flag is given, then a
FormatFlagsConversionMismatchException
will be thrown.
The width is the minimum number of characters to be written to the output.
width
then the output will be padded by spaces (
'\u0020'
) until the total number of characters equals width. The padding is on the left by default.
'-'
flag is given then the padding will be on the right. If width is not specified then there is no minimum.
The precision is not applicable. If the precision is specified then an
IllegalFormatPrecisionException
will be thrown.
Percent
The conversion does not correspond to any argument.
'%'
The result is a literal
'%'
(
'\u0025'
)
The width is the minimum number of characters to be written to the output including the
'%'
.
width
then the output will be padded by spaces (
'\u0020'
) until the total number of characters equals width. The padding is on the left.
'%'
is output.
The
'-'
flag defined for
General conversions
applies. If any other flags are provided, then a
FormatFlagsConversionMismatchException
will be thrown.
The precision is not applicable. If the precision is specified an
IllegalFormatPrecisionException
will be thrown.
Line Separator
The conversion does not correspond to any argument.
'n'
the platform-specific line separator as returned by
System.getProperty("line.separator")
.
Flags, width, and precision are not applicable. If any are provided an
IllegalFormatFlagsException
,
IllegalFormatWidthException
, and
IllegalFormatPrecisionException
, respectively will be thrown.
Argument Index
Format specifiers can reference arguments in three ways:
Explicit indexing
is used when the format specifier contains an argument index. The argument index is a decimal integer indicating the position of the argument in the argument list.
1$
", the second by "
2$
", etc. An argument may be referenced more than once.
formatter.format("%4$s %3$s %2$s %1$s %4$s %3$s %2$s %1$s",
"a", "b", "c", "d")
// -> "d c b a d c b a"
Relative indexing
is used when the format specifier contains a
'
<'
(
'\u003c'
) flag which causes the argument for the previous format specifier to be re-used. If there is no previous argument, then a
MissingFormatArgumentException
is thrown.
formatter.format("%s %s %<s %<s", "a", "b", "c", "d")
// -> "a b b b"
// "c" and "d" are ignored because they are not referenced
Ordinary indexing
is used when the format specifier contains neither an argument index nor a
'
<'
flag. Each format specifier which uses ordinary indexing is assigned a sequential implicit index into argument list which is independent of the indices used by explicit or relative indexing.
formatter.format("%s %s %s %s", "a", "b", "c", "d")
// -> "a b c d"
It is possible to have a format string which uses all forms of indexing, for example:
formatter.format("%2$s %s %<s %s", "a", "b", "c", "d")
// -> "b a a b"
// "c" and "d" are ignored because they are not referenced
The maximum number of arguments is limited by the maximum dimension of a Java array as defined by the
Java Virtual Machine Specification
. If the argument index is does not correspond to an available argument, then a
MissingFormatArgumentException
is thrown.
If there are more arguments than format specifiers, the extra arguments are ignored.
Unless otherwise specified, passing a
null
argument to any method or constructor in this class will cause a
NullPointerException
Nested Class Summary
static class
Formatter.BigDecimalLayoutForm
Constructor Summary
Formatter
()
Constructs a new formatter.
Formatter
(
Appendable
Constructs a new formatter with the specified destination.
Formatter
(
Appendable
a,
Locale
Constructs a new formatter with the specified destination and locale.
Formatter
(
File
Constructs a new formatter with the specified file.
Formatter
(
File
file,
String
Constructs a new formatter with the specified file and charset.
Formatter
(
File
file,
String
csn,
Locale
Constructs a new formatter with the specified file, charset, and locale.
Formatter
(
Locale
Constructs a new formatter with the specified locale.
Formatter
(
OutputStream
Constructs a new formatter with the specified output stream.
Formatter
(
OutputStream
os,
String
Constructs a new formatter with the specified output stream and charset.
Formatter
(
OutputStream
os,
String
csn,
Locale
Constructs a new formatter with the specified output stream, charset, and locale.
Formatter
(
PrintStream
Constructs a new formatter with the specified print stream.
Formatter
(
String
Constructs a new formatter with the specified file name.
Formatter
(
String
fileName,
String
Constructs a new formatter with the specified file name and charset.
Formatter
(
String
fileName,
String
csn,
Locale
Constructs a new formatter with the specified file name, charset, and locale.
Method Summary
void
close
()
Closes this formatter.
void
flush
()
Flushes this formatter.
Formatter
format
(
Locale
l,
String
format,
Object
Writes a formatted string to this object's destination using the specified locale, format string, and arguments.
Formatter
format
(
String
format,
Object
Writes a formatted string to this object's destination using the specified format string and arguments.
IOException
ioException
()
Returns the
IOException
last thrown by this formatter's
Appendable
Locale
locale
()
Returns the locale set by the construction of this formatter.
Appendable
out
()
Returns the destination for the output.
String
toString
()
Returns the result of invoking
toString()
on the destination for the output.
Methods inherited from class java.lang.
Object
clone
,
equals
,
finalize
,
getClass
,
hashCode
,
notify
,
notifyAll
,
wait
,
wait
,
wait
Constructor Detail
Formatter
public Formatter ()
Constructs a new formatter.
The destination of the formatted output is a
StringBuilder
which may be retrieved by invoking
out()
and whose current content may be converted into a string by invoking
toString()
. The locale used is the
default locale
for this instance of the Java virtual machine.
Formatter
public Formatter ( Appendable a)
Constructs a new formatter with the specified destination.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
a - Destination for the formatted output. If
'#'
a
is
'\u0023'
null
Requires the output use an alternate form. The definition of the form is specified by the conversion.
then a
StringBuilder
will be created.
Formatter
public Formatter ( Locale l)
Constructs a new formatter with the specified locale.
The destination of the formatted output is a
StringBuilder
which may be retrieved by invoking
out()
and whose current content may be converted into a string by invoking
toString()
.
Parameters:
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Formatter
public Formatter ( Appendable a,
Locale l)
Constructs a new formatter with the specified destination and locale.
Parameters:
a - Destination for the formatted output. If
a
is
null
then a
StringBuilder
will be created.
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Formatter
public Formatter ( String fileName)
throws FileNotFoundException
Constructs a new formatter with the specified file name.
The charset used is the
default charset
for this instance of the Java virtual machine.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
fileName - The name of the file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
Throws:
SecurityException
- If a security manager is present and
checkWrite(fileName)
denies write access to the file
FileNotFoundException
- If the given file name does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
Formatter
public Formatter ( String fileName,
String csn)
throws FileNotFoundException,
UnsupportedEncodingException
Constructs a new formatter with the specified file name and charset.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
fileName - The name of the file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn - The name of a supported
charset
Throws:
FileNotFoundException
- If the given file name does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException
- If a security manager is present and
checkWrite(fileName)
denies write access to the file
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public Formatter ( String fileName,
String csn,
Locale l)
throws FileNotFoundException,
UnsupportedEncodingException
Constructs a new formatter with the specified file name, charset, and locale.
Parameters:
fileName - The name of the file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn - The name of a supported
charset
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Throws:
FileNotFoundException
- If the given file name does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException
- If a security manager is present and
checkWrite(fileName)
denies write access to the file
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public Formatter ( File file)
throws FileNotFoundException
Constructs a new formatter with the specified file.
The charset used is the
default charset
for this instance of the Java virtual machine.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
file - The file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
Throws:
SecurityException
- If a security manager is present and
checkWrite(file.getPath())
denies write access to the file
FileNotFoundException
- If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
Formatter
public Formatter ( File file,
String csn)
throws FileNotFoundException,
UnsupportedEncodingException
Constructs a new formatter with the specified file and charset.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
file - The file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn - The name of a supported
charset
Throws:
FileNotFoundException
- If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException
- If a security manager is present and
checkWrite(file.getPath())
denies write access to the file
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public Formatter ( File file,
String csn,
Locale l)
throws FileNotFoundException,
UnsupportedEncodingException
Constructs a new formatter with the specified file, charset, and locale.
Parameters:
file - The file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn - The name of a supported
charset
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Throws:
FileNotFoundException
- If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException
- If a security manager is present and
checkWrite(file.getPath())
denies write access to the file
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public Formatter ( PrintStream ps)
Constructs a new formatter with the specified print stream.
The locale used is the
default locale
for this instance of the Java virtual machine.
Characters are written to the given
PrintStream
object and are therefore encoded using that object's charset.
Formatter
public Formatter ( OutputStream os)
Constructs a new formatter with the specified output stream.
The charset used is the
default charset
for this instance of the Java virtual machine.
The locale used is the
default locale
for this instance of the Java virtual machine.
Formatter
public Formatter ( OutputStream os,
String csn)
throws UnsupportedEncodingException
Constructs a new formatter with the specified output stream and charset.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
os - The output stream to use as the destination of this formatter. The output will be buffered.
csn - The name of a supported
charset
Throws:
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public Formatter ( OutputStream os,
String csn,
Locale l)
throws UnsupportedEncodingException
Constructs a new formatter with the specified output stream, charset, and locale.
Parameters:
os - The output stream to use as the destination of this formatter. The output will be buffered.
csn - The name of a supported
charset
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Throws:
UnsupportedEncodingException
- If the named charset is not supported
Method Detail
The
width
is the minimum number of characters to be written to the output. If the length of the converted value is less than the width then the output will be padded by
' '
(
\u0020'
) until the total number of characters equals the width. The padding is on the left by default. If the
'-'
flag is given, then the padding will be on the right. If the width is not specified then there is no minimum.
The precision is the maximum number of characters to be written to the output. The precision is applied before the width, thus the output will be truncated to
precision
characters even if the width is greater than the precision. If the precision is not specified then there is no explicit limit on the number of characters.
Character
This conversion may be applied to
char
and
Character
. It may also be applied to the types
byte
,
Byte
,
short
, and
Short
,
int
and
Integer
when
Character.isValidCodePoint(int)
returns
true
. If it returns
false
then an
IllegalFormatCodePointException
will be thrown.
'c'
'\u0063'
Formats the argument as a Unicode character as described in
Unicode Character Representation
. This may be more than one 16-bit
char
in the case where the argument represents a supplementary character.
If the
'#'
flag is given, then a
FormatFlagsConversionMismatchException
will be thrown.
'C'
'\u0043'
The upper-case variant of
'c'
.
The
'-'
flag defined for
General conversions
applies. If the
'#'
flag is given, then a
FormatFlagsConversionMismatchException
will be thrown.
The width is defined as for
General conversions
.
The precision is not applicable. If the precision is specified then an
IllegalFormatPrecisionException
will be thrown.
Numeric
Numeric conversions are divided into the following categories:
Numeric types will be formatted according to the following algorithm:
After digits are obtained for the integer part, fractional part, and exponent (as appropriate for the data type), the following transformation is applied:
Each digit character
d
in the string is replaced by a locale-specific digit computed relative to the current locale's
zero digit
z
; that is
d -
'0'
+ z
.
If a decimal separator is present, a locale-specific
decimal separator
is substituted.
If the
','
(
'\u002c'
)
flag
is given, then the locale-specific
grouping separator
is inserted by scanning the integer part of the string from least significant to most significant digits and inserting a separator at intervals defined by the locale's
grouping size
.
If the
'0'
flag is given, then the locale-specific
zero digits
are inserted after the sign character, if any, and before the first non-zero digit, until the length of the string is equal to the requested field width.
If the value is negative and the
'('
flag is given, then a
'('
(
'\u0028'
) is prepended and a
')'
(
'\u0029'
) is appended.
If the value is negative (or floating-point negative zero) and
'('
flag is not given, then a
'-'
(
'\u002d'
) is prepended.
If the
'+'
flag is given and the value is positive or zero (or floating-point positive zero), then a
'+'
(
'\u002b'
) will be prepended.
If the value is NaN or positive infinity the literal strings "NaN" or "Infinity" respectively, will be output. If the value is negative infinity, then the output will be "(Infinity)" if the
'('
flag is given otherwise the output will be "-Infinity". These values are not localized.
Byte, Short, Integer, and Long
The following conversions may be applied to
byte
,
Byte
,
short
,
Short
,
int
and
Integer
,
long
, and
Long
.
'd'
'\u0054'
Formats the argument as a decimal integer. The
localization algorithm
is applied.
If the
'0'
flag is given and the value is negative, then the zero padding will occur after the sign.
If the
'#'
flag is given then a
FormatFlagsConversionMismatchException
will be thrown.
'o'
'\u006f'
Formats the argument as an integer in base eight. No localization is applied.
If
x
is negative then the result will be an unsigned value generated by adding 2
n
to the value where
n
is the number of bits in the type as returned by the static
SIZE
field in the
Byte
,
Short
,
Integer
, or
Long
classes as appropriate.
If the
'#'
flag is given then the output will always begin with the radix indicator
'0'
.
If the
'0'
flag is given then the output will be padded with leading zeros to the field width following any indication of sign.
If
'('
,
'+'
, '  ', or
','
flags are given then a
FormatFlagsConversionMismatchException
will be thrown.
'x'
'\u0078'
Formats the argument as an integer in base sixteen. No localization is applied.
If
x
is negative then the result will be an unsigned value generated by adding 2
n
to the value where
n
is the number of bits in the type as returned by the static
SIZE
field in the
Byte
,
Short
,
Integer
, or
Long
classes as appropriate.
If the
'#'
flag is given then the output will always begin with the radix indicator
"0x"
.
If the
'0'
flag is given then the output will be padded to the field width with leading zeros after the radix indicator or sign (if present).
If
'('
,
' '
,
'+'
, or
','
flags are given then a
FormatFlagsConversionMismatchException
will be thrown.
'X'
'\u0058'
The upper-case variant of
'x'
. The entire string representing the number will be converted to
upper case
including the
'x'
(if any) and all hexadecimal digits
'a'
-
'f'
(
'\u0061'
-
'\u0066'
).
If the conversion is
'o'
,
'x'
, or
'X'
and both the
'#'
and the
'0'
flags are given, then result will contain the radix indicator (
'0'
for octal and
"0x"
or
"0X"
for hexadecimal), some number of zeros (based on the width), and the value.
If the
'-'
flag is not given, then the space padding will occur before the sign.
The following
flags
apply to numeric integral conversions:
'+'
'\u002b'
Requires the output to include a positive sign for all positive numbers. If this flag is not given then only negative values will include a sign.
If both the
'+'
and
' '
flags are given then an
IllegalFormatFlagsException
will be thrown.
' '
'\u0020'
Requires the output to include a single extra space (
'\u0020'
) for non-negative values.
If both the
'+'
and
' '
flags are given then an
IllegalFormatFlagsException
will be thrown.
'0'
'\u0030'
Requires the output to be padded with leading
zeros
to the minimum field width following any sign or radix indicator except when converting NaN or infinity. If the width is not provided, then a
MissingFormatWidthException
will be thrown.
If both the
'-'
and
'0'
flags are given then an
IllegalFormatFlagsException
will be thrown.
','
'\u002c'
Requires the output to include the locale-specific
group separators
as described in the
"group" section
of the localization algorithm.
'('
'\u0028'
Requires the output to prepend a
'('
(
'\u0028'
) and append a
')'
(
'\u0029'
) to negative values.
If no
flags
are given the default formatting is as follows:
The output is right-justified within the
width
Negative numbers begin with a
'-'
(
'\u002d'
)
Positive numbers and zero do not include a sign or extra leading space
No grouping separators are included
The
width
is the minimum number of characters to be written to the output. This includes any signs, digits, grouping separators, radix indicator, and parentheses. If the length of the converted value is less than the width then the output will be padded by spaces (
'\u0020'
) until the total number of characters equals width. The padding is on the left by default. If
'-'
flag is given then the padding will be on the right. If width is not specified then there is no minimum.
The precision is not applicable. If precision is specified then an
IllegalFormatPrecisionException
will be thrown.
The following conversions may be applied to
BigInteger
.
'd'
'\u0054'
Requires the output to be formatted as a decimal integer. The
localization algorithm
is applied.
If the
'#'
flag is given
FormatFlagsConversionMismatchException
will be thrown.
'o'
'\u006f'
Requires the output to be formatted as an integer in base eight. No localization is applied.
If
x
is negative then the result will be a signed value beginning with
'-'
(
'\u002d'
). Signed output is allowed for this type because unlike the primitive types it is not possible to create an unsigned equivalent without assuming an explicit data-type size.
If
x
is positive or zero and the
'+'
flag is given then the result will begin with
'+'
(
'\u002b'
).
If the
'#'
flag is given then the output will always begin with
'0'
prefix.
If the
'0'
flag is given then the output will be padded with leading zeros to the field width following any indication of sign.
If the
','
flag is given then a
FormatFlagsConversionMismatchException
will be thrown.
'x'
'\u0078'
Requires the output to be formatted as an integer in base sixteen. No localization is applied.
If
x
is negative then the result will be a signed value beginning with
'-'
(
'\u002d'
). Signed output is allowed for this type because unlike the primitive types it is not possible to create an unsigned equivalent without assuming an explicit data-type size.
If
x
is positive or zero and the
'+'
flag is given then the result will begin with
'+'
(
'\u002b'
).
If the
'#'
flag is given then the output will always begin with the radix indicator
"0x"
.
If the
'0'
flag is given then the output will be padded to the field width with leading zeros after the radix indicator or sign (if present).
If the
','
flag is given then a
FormatFlagsConversionMismatchException
will be thrown.
'X'
'\u0058'
The upper-case variant of
'x'
. The entire string representing the number will be converted to
upper case
including the
'x'
(if any) and all hexadecimal digits
'a'
-
'f'
(
'\u0061'
-
'\u0066'
).
If the conversion is
'o'
,
'x'
, or
'X'
and both the
'#'
and the
'0'
flags are given, then result will contain the base indicator (
'0'
for octal and
"0x"
or
"0X"
for hexadecimal), some number of zeros (based on the width), and the value.
If the
'0'
flag is given and the value is negative, then the zero padding will occur after the sign.
If the
'-'
flag is not given, then the space padding will occur before the sign.
All
flags
defined for Byte, Short, Integer, and Long apply. The
default behavior
when no flags are given is the same as for Byte, Short, Integer, and Long.
The specification of
width
is the same as defined for Byte, Short, Integer, and Long.
The precision is not applicable. If precision is specified then an
IllegalFormatPrecisionException
will be thrown.
The following conversions may be applied to
float
,
Float
,
double
and
Double
.
'e'
'\u0065'
Requires the output to be formatted using
computerized scientific notation
. The
localization algorithm
is applied.
The formatting of the magnitude
m
depends upon its value.
If
m
is NaN or infinite, the literal strings "NaN" or "Infinity", respectively, will be output. These values are not localized.
If
m
is positive-zero or negative-zero, then the exponent will be
"+00"
.
Otherwise, the result is a string that represents the sign and magnitude (absolute value) of the argument. The formatting of the sign is described in the
localization algorithm
. The formatting of the magnitude
m
depends upon its value.
Let
n
be the unique integer such that 10
n
<=
m
< 10
n
+1
; then let
a
be the mathematically exact quotient of
m
and 10
n
so that 1 <=
a
< 10. The magnitude is then represented as the integer part of
a
, as a single decimal digit, followed by the decimal separator followed by decimal digits representing the fractional part of
a
, followed by the exponent symbol
'e'
(
'\u0065'
), followed by the sign of the exponent, followed by a representation of
n
as a decimal integer, as produced by the method
Long.toString(long, int)
, and zero-padded to include at least two digits.
The number of digits in the result for the fractional part of
m
or
a
is equal to the precision. If the precision is not specified then the default value is
6
. If the precision is less than the number of digits which would appear after the decimal point in the string returned by
Float.toString(float)
or
Double.toString(double)
respectively, then the value will be rounded using the
round half up algorithm
. Otherwise, zeros may be appended to reach the precision. For a canonical representation of the value, use
Float.toString(float)
or
Double.toString(double)
as appropriate.
If the
','
flag is given, then an
FormatFlagsConversionMismatchException
will be thrown.
'E'
'\u0045'
The upper-case variant of
'e'
. The exponent symbol will be
'E'
(
'\u0045'
).
'g'
'\u0067'
Requires the output to be formatted in general scientific notation as described below. The
localization algorithm
is applied.
After rounding for the precision, the formatting of the resulting magnitude
m
depends on its value.
If
m
is greater than or equal to 10
-4
but less than 10
precision
then it is represented in
decimal format
.
If
m
is less than 10
-4
or greater than or equal to 10
precision
, then it is represented in
computerized scientific notation
.
The total number of significant digits in
m
is equal to the precision. If the precision is not specified, then the default value is
6
. If the precision is
0
, then it is taken to be
1
.
If the
'#'
flag is given then an
FormatFlagsConversionMismatchException
will be thrown.
'G'
'\u0047'
The upper-case variant of
'g'
.
'f'
'\u0066'
Requires the output to be formatted using
decimal format
. The
localization algorithm
is applied.
The result is a string that represents the sign and magnitude (absolute value) of the argument. The formatting of the sign is described in the
localization algorithm
. The formatting of the magnitude
m
depends upon its value.
If
m
NaN or infinite, the literal strings "NaN" or "Infinity", respectively, will be output. These values are not localized.
The magnitude is formatted as the integer part of
m
, with no leading zeroes, followed by the decimal separator followed by one or more decimal digits representing the fractional part of
m
.
The number of digits in the result for the fractional part of
m
or
a
is equal to the precision. If the precision is not specified then the default value is
6
. If the precision is less than the number of digits which would appear after the decimal point in the string returned by
Float.toString(float)
or
Double.toString(double)
respectively, then the value will be rounded using the
round half up algorithm
. Otherwise, zeros may be appended to reach the precision. For a canonical representation of the value,use
Float.toString(float)
or
Double.toString(double)
as appropriate.
'a'
'\u0061'
Requires the output to be formatted in hexadecimal exponential form. No localization is applied.
The result is a string that represents the sign and magnitude (absolute value) of the argument
x
.
If
x
is negative or a negative-zero value then the result will begin with
'-'
(
'\u002d'
).
If
x
is positive or a positive-zero value and the
'+'
flag is given then the result will begin with
'+'
(
'\u002b'
).
The formatting of the magnitude
m
depends upon its value.
If the value is NaN or infinite, the literal strings "NaN" or "Infinity", respectively, will be output.
If
m
is zero then it is represented by the string
"0x0.0p0"
.
If
m
is a
double
value with a normalized representation then substrings are used to represent the significand and exponent fields. The significand is represented by the characters
"0x1."
followed by the hexadecimal representation of the rest of the significand as a fraction. The exponent is represented by
'p'
(
'\u0070'
) followed by a decimal string of the unbiased exponent as if produced by invoking
Integer.toString
on the exponent value.
If
m
is a
double
value with a subnormal representation then the significand is represented by the characters
'0x0.'
followed by the hexadecimal representation of the rest of the significand as a fraction. The exponent is represented by
'p-1022'
. Note that there must be at least one nonzero digit in a subnormal significand.
If the
'('
or
','
flags are given, then a
FormatFlagsConversionMismatchException
will be thrown.
'A'
'\u0041'
The upper-case variant of
'a'
. The entire string representing the number will be converted to upper case including the
'x'
(
'\u0078'
) and
'p'
(
'\u0070'
and all hexadecimal digits
'a'
-
'f'
(
'\u0061'
-
'\u0066'
).
All
flags
defined for Byte, Short, Integer, and Long apply.
If the
'#'
flag is given, then the decimal separator will always be present.
If no
flags
are given the default formatting is as follows:
The output is right-justified within the
width
Negative numbers begin with a
'-'
Positive numbers and positive zero do not include a sign or extra leading space
No grouping separators are included
The decimal separator will only appear if a digit follows it
The
width
is the minimum number of characters to be written to the output. This includes any signs, digits, grouping separators, decimal separators, exponential symbol, radix indicator, parentheses, and strings representing infinity and NaN as applicable. If the length of the converted value is less than the width then the output will be padded by spaces (
'\u0020'
) until the total number of characters equals width. The padding is on the left by default. If the
'-'
flag is given then the padding will be on the right. If width is not specified then there is no minimum.
If the
conversion
is
'e'
,
'E'
or
'f'
, then the precision is the number of digits after the decimal separator. If the precision is not specified, then it is assumed to be
6
.
If the conversion is
'g'
or
'G'
, then the precision is the total number of significant digits in the resulting magnitude after rounding. If the precision is not specified, then the default value is
6
. If the precision is
0
, then it is taken to be
1
.
If the conversion is
'a'
or
'A'
, then the precision is the number of hexadecimal digits after the decimal separator. If the precision is not provided, then all of the digits as returned by
Double.toHexString(double)
will be output.
The following conversions may be applied
BigDecimal
.
'e'
'\u0065'
Requires the output to be formatted using
computerized scientific notation
. The
localization algorithm
is applied.
The formatting of the magnitude
m
depends upon its value.
If
m
is positive-zero or negative-zero, then the exponent will be
"+00"
.
Otherwise, the result is a string that represents the sign and magnitude (absolute value) of the argument. The formatting of the sign is described in the
localization algorithm
. The formatting of the magnitude
m
depends upon its value.
Let
n
be the unique integer such that 10
n
<=
m
< 10
n
+1
; then let
a
be the mathematically exact quotient of
m
and 10
n
so that 1 <=
a
< 10. The magnitude is then represented as the integer part of
a
, as a single decimal digit, followed by the decimal separator followed by decimal digits representing the fractional part of
a
, followed by the exponent symbol
'e'
(
'\u0065'
), followed by the sign of the exponent, followed by a representation of
n
as a decimal integer, as produced by the method
Long.toString(long, int)
, and zero-padded to include at least two digits.
The number of digits in the result for the fractional part of
m
or
a
is equal to the precision. If the precision is not specified then the default value is
6
. If the precision is less than the number of digits which would appear after the decimal point in the string returned by
Float.toString(float)
or
Double.toString(double)
respectively, then the value will be rounded using the
round half up algorithm
. Otherwise, zeros may be appended to reach the precision. For a canonical representation of the value, use
BigDecimal.toString()
.
If the
','
flag is given, then an
FormatFlagsConversionMismatchException
will be thrown.
'E'
'\u0045'
The upper-case variant of
'e'
. The exponent symbol will be
'E'
(
'\u0045'
).
'g'
'\u0067'
Requires the output to be formatted in general scientific notation as described below. The
localization algorithm
is applied.
After rounding for the precision, the formatting of the resulting magnitude
m
depends on its value.
If
m
is greater than or equal to 10
-4
but less than 10
precision
then it is represented in
decimal format
.
If
m
is less than 10
-4
or greater than or equal to 10
precision
, then it is represented in
computerized scientific notation
.
The total number of significant digits in
m
is equal to the precision. If the precision is not specified, then the default value is
6
. If the precision is
0
, then it is taken to be
1
.
If the
'#'
flag is given then an
FormatFlagsConversionMismatchException
will be thrown.
'G'
'\u0047'
The upper-case variant of
'g'
.
'f'
'\u0066'
Requires the output to be formatted using
decimal format
. The
localization algorithm
is applied.
The result is a string that represents the sign and magnitude (absolute value) of the argument. The formatting of the sign is described in the
localization algorithm
. The formatting of the magnitude
m
depends upon its value.
The magnitude is formatted as the integer part of
m
, with no leading zeroes, followed by the decimal separator followed by one or more decimal digits representing the fractional part of
m
.
The number of digits in the result for the fractional part of
m
or
a
is equal to the precision. If the precision is not specified then the default value is
6
. If the precision is less than the number of digits which would appear after the decimal point in the string returned by
Float.toString(float)
or
Double.toString(double)
respectively, then the value will be rounded using the
round half up algorithm
. Otherwise, zeros may be appended to reach the precision. For a canonical representation of the value, use
BigDecimal.toString()
.
All
flags
defined for Byte, Short, Integer, and Long apply.
If the
'#'
flag is given, then the decimal separator will always be present.
The
default behavior
when no flags are given is the same as for Float and Double.
The specification of
width
and
precision
is the same as defined for Float and Double.
Date/Time
This conversion may be applied to
long
,
Long
,
Calendar
, and
Date
.
't'
'\u0074'
Prefix for date and time conversion characters.
'T'
'\u0054'
The upper-case variant of
't'
.
The following date and time conversion character suffixes are defined for the
't'
and
'T'
conversions. The types are similar to but not completely identical to those defined by GNU
date
and POSIX
strftime(3c)
. Additional conversion types are provided to access Java-specific functionality (e.g.
'L'
for milliseconds within the second).
The following conversion characters are used for formatting times:
'H'
'\u0048'
Hour of the day for the 24-hour clock, formatted as two digits with a leading zero as necessary i.e.
00 - 23
.
00
corresponds to midnight.
'I'
'\u0049'
Hour for the 12-hour clock, formatted as two digits with a leading zero as necessary, i.e.
01 - 12
.
01
corresponds to one o'clock (either morning or afternoon).
'k'
'\u006b'
Hour of the day for the 24-hour clock, i.e.
0 - 23
.
0
corresponds to midnight.
'l'
'\u006c'
Hour for the 12-hour clock, i.e.
1 - 12
.
1
corresponds to one o'clock (either morning or afternoon).
'M'
'\u004d'
Minute within the hour formatted as two digits with a leading zero as necessary, i.e.
00 - 59
.
'S'
'\u0053'
Seconds within the minute, formatted as two digits with a leading zero as necessary, i.e.
00 - 60
("
60
" is a special value required to support leap seconds).
'L'
'\u004c'
Millisecond within the second formatted as three digits with leading zeros as necessary, i.e.
000 - 999
.
'N'
'\u004e'
Nanosecond within the second, formatted as nine digits with leading zeros as necessary, i.e.
000000000 - 999999999
. The precision of this value is limited by the resolution of the underlying operating system or hardware.
'p'
'\u0070'
Locale-specific
morning or afternoon
marker in lower case, e.g."
am
" or "
pm
". Use of the conversion prefix
'T'
forces this output to upper case. (Note that
'p'
produces lower-case output. This is different from GNU
date
and POSIX
strftime(3c)
which produce upper-case output.)
'z'
'\u007a'
RFC 822
style numeric time zone offset from GMT, e.g.
-0800
.
'Z'
'\u005a'
A string representing the abbreviation for the time zone.
's'
'\u0073'
Seconds since the beginning of the epoch starting at 1 January 1970
00:00:00
UTC, i.e.
Long.MIN_VALUE/1000
to
Long.MAX_VALUE/1000
.
'Q'
'\u004f'
Milliseconds since the beginning of the epoch starting at 1 January 1970
00:00:00
UTC, i.e.
Long.MIN_VALUE
to
Long.MAX_VALUE
. The precision of this value is limited by the resolution of the underlying operating system or hardware.
The following conversion characters are used for formatting dates:
'B'
'\u0042'
Locale-specific
full month name
, e.g.
"January"
,
"February"
.
'b'
'\u0062'
Locale-specific
abbreviated month name
, e.g.
"Jan"
,
"Feb"
.
'h'
'\u0068'
Same as
'b'
.
'A'
'\u0041'
Locale-specific full name of the
day of the week
, e.g.
"Sunday"
,
"Monday"
'a'
'\u0061'
Locale-specific short name of the
day of the week
, e.g.
"Sun"
,
"Mon"
'C'
'\u0043'
Four-digit year divided by
100
, formatted as two digits with leading zero as necessary, i.e.
00 - 99
'Y'
'\u0059'
Year, formatted to at least four digits with leading zeros as necessary, e.g.
0092
equals
92
CE for the Gregorian calendar.
'y'
'\u0079'
Last two digits of the year, formatted with leading zeros as necessary, i.e.
00 - 99
.
'j'
'\u006a'
Day of year, formatted as three digits with leading zeros as necessary, e.g.
001 - 366
for the Gregorian calendar.
001
corresponds to the first day of the year.
'm'
'\u006d'
Month, formatted as two digits with leading zeros as necessary, i.e.
01 - 13
, where "
01
" is the first month of the year and ("
13
" is a special value required to support lunar calendars).
'd'
'\u0064'
Day of month, formatted as two digits with leading zeros as necessary, i.e.
01 - 31
, where "
01
" is the first day of the month.
'e'
'\u0065'
Day of month, formatted as two digits, i.e.
1 - 31
where "
1
" is the first day of the month.
The following conversion characters are used for formatting common date/time compositions.
'R'
'\u0052'
Time formatted for the 24-hour clock as
"%tH:%tM"
'T'
'\u0054'
Time formatted for the 24-hour clock as
"%tH:%tM:%tS"
.
'r'
'\u0072'
Time formatted for the 12-hour clock as
"%tI:%tM:%tS %Tp"
. The location of the morning or afternoon marker (
'%Tp'
) may be locale-dependent.
'D'
'\u0044'
Date formatted as
"%tm/%td/%ty"
.
'F'
'\u0046'
ISO 8601
complete date formatted as
"%tY-%tm-%td"
.
'c'
'\u0063'
Date and time formatted as
"%ta %tb %td %tT %tZ %tY"
, e.g.
"Sun Jul 20 16:17:00 EDT 1969"
.
The
'-'
flag defined for
General conversions
applies. If the
'#'
flag is given, then a
FormatFlagsConversionMismatchException
will be thrown.
The
width
is the minimum number of characters to be written to the output. If the length of the converted value is less than the
width
then the output will be padded by spaces (
'\u0020'
) until the total number of characters equals width. The padding is on the left by default. If the
'-'
flag is given then the padding will be on the right. If width is not specified then there is no minimum.
The precision is not applicable. If the precision is specified then an
IllegalFormatPrecisionException
will be thrown.
Percent
The conversion does not correspond to any argument.
'%'
The result is a literal
'%'
(
'\u0025'
)
The
width
is the minimum number of characters to be written to the output including the
'%'
. If the length of the converted value is less than the
width
then the output will be padded by spaces (
'\u0020'
) until the total number of characters equals width. The padding is on the left. If width is not specified then just the
'%'
is output.
The
'-'
flag defined for
General conversions
applies. If any other flags are provided, then a
FormatFlagsConversionMismatchException
will be thrown.
The precision is not applicable. If the precision is specified an
IllegalFormatPrecisionException
will be thrown.
Line Separator
The conversion does not correspond to any argument.
'n'
the platform-specific line separator as returned by
System.getProperty("line.separator")
.
Flags, width, and precision are not applicable. If any are provided an
IllegalFormatFlagsException
,
IllegalFormatWidthException
, and
IllegalFormatPrecisionException
, respectively will be thrown.
Argument Index
Format specifiers can reference arguments in three ways:
Explicit indexing
is used when the format specifier contains an argument index. The argument index is a decimal integer indicating the position of the argument in the argument list. The first argument is referenced by "
1$
", the second by "
2$
", etc. An argument may be referenced more than once.
formatter.format("%4$s %3$s %2$s %1$s %4$s %3$s %2$s %1$s",
"a", "b", "c", "d")
// -> "d c b a d c b a"
Relative indexing
is used when the format specifier contains a
'<'
(
'\u003c'
) flag which causes the argument for the previous format specifier to be re-used. If there is no previous argument, then a
MissingFormatArgumentException
formatter.format("%s %s %<s %<s", "a", "b", "c", "d")
// -> "a b b b"
// "c" and "d" are ignored because they are not referenced
Ordinary indexing
is used when the format specifier contains neither an argument index nor a
'<'
flag. Each format specifier which uses ordinary indexing is assigned a sequential implicit index into argument list which is independent of the indices used by explicit or relative indexing.
formatter.format("%s %s %s %s", "a", "b", "c", "d")
// -> "a b c d"
It is possible to have a format string which uses all forms of indexing, for example:
formatter.format("%2$s %s %<s %s", "a", "b", "c", "d")
// -> "b a a b"
// "c" and "d" are ignored because they are not referenced
The maximum number of arguments is limited by the maximum dimension of a Java array as defined by the
Java Virtual Machine Specification
. If the argument index is does not correspond to an available argument, then a
MissingFormatArgumentException
is thrown.
If there are more arguments than format specifiers, the extra arguments are ignored.
Unless otherwise specified, passing a
null
argument to any method or constructor in this class will cause a
NullPointerException
to be thrown.
Nested Class Summary
static class
Formatter.BigDecimalLayoutForm
Constructor Summary
Formatter
()
Constructs a new formatter.
Formatter
(
Appendable
Constructs a new formatter with the specified destination.
Formatter
(
Appendable
a,
Locale
Constructs a new formatter with the specified destination and locale.
Formatter
(
File
Constructs a new formatter with the specified file.
Formatter
(
File
file,
String
Constructs a new formatter with the specified file and charset.
Formatter
(
File
file,
String
csn,
Locale
Constructs a new formatter with the specified file, charset, and locale.
Formatter
(
Locale
Constructs a new formatter with the specified locale.
Formatter
(
OutputStream
Constructs a new formatter with the specified output stream.
Formatter
(
OutputStream
os,
String
Constructs a new formatter with the specified output stream and charset.
Formatter
(
OutputStream
os,
String
csn,
Locale
Constructs a new formatter with the specified output stream, charset, and locale.
Formatter
(
PrintStream
Constructs a new formatter with the specified print stream.
Formatter
(
String
Constructs a new formatter with the specified file name.
Formatter
(
String
fileName,
String
Constructs a new formatter with the specified file name and charset.
Formatter
(
String
fileName,
String
csn,
Locale
Constructs a new formatter with the specified file name, charset, and locale.
Method Summary
void
close
()
Closes this formatter.
void
flush
()
Flushes this formatter.
Formatter
format
(
Locale
l,
String
format,
Object
Writes a formatted string to this object's destination using the specified locale, format string, and arguments.
Formatter
format
(
String
format,
Object
Writes a formatted string to this object's destination using the specified format string and arguments.
IOException
ioException
()
Returns the
IOException
last thrown by this formatter's
Appendable
Locale
locale
()
Returns the locale set by the construction of this formatter.
Appendable
out
()
Returns the destination for the output.
String
toString
()
Returns the result of invoking
toString()
on the destination for the output.
Methods inherited from class java.lang.
Object
clone
,
equals
,
finalize
,
getClass
,
hashCode
,
notify
,
notifyAll
,
wait
,
wait
,
wait
Constructor Detail
Formatter
public
Formatter
()
Constructs a new formatter.
The destination of the formatted output is a
StringBuilder
which may be retrieved by invoking
out()
and whose current content may be converted into a string by invoking
toString()
. The locale used is the
default locale
for this instance of the Java virtual machine.
Formatter
public
Formatter
(
Appendable
a)
Constructs a new formatter with the specified destination.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
a - Destination for the formatted output. If
a
is
null
then a
StringBuilder
will be created.
Formatter
public
Formatter
(
Locale
l)
Constructs a new formatter with the specified locale.
The destination of the formatted output is a
StringBuilder
which may be retrieved by invoking
out()
and whose current content may be converted into a string by invoking
toString()
.
Parameters:
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Formatter
public
Formatter
(
Appendable
a,
Locale
l)
Constructs a new formatter with the specified destination and locale.
Parameters:
a - Destination for the formatted output. If
a
is
null
then a
StringBuilder
will be created.
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Formatter
public
Formatter
(
String
fileName)
throws
FileNotFoundException
Constructs a new formatter with the specified file name.
The charset used is the
default charset
for this instance of the Java virtual machine.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
fileName - The name of the file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
Throws:
SecurityException
- If a security manager is present and
checkWrite(fileName)
denies write access to the file
FileNotFoundException
- If the given file name does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
Formatter
public
Formatter
(
String
fileName,
String
csn)
throws
FileNotFoundException
,
UnsupportedEncodingException
Constructs a new formatter with the specified file name and charset.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
fileName - The name of the file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn - The name of a supported
charset
Throws:
FileNotFoundException
- If the given file name does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException
- If a security manager is present and
checkWrite(fileName)
denies write access to the file
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public
Formatter
(
String
fileName,
String
csn,
Locale
l)
throws
FileNotFoundException
,
UnsupportedEncodingException
Constructs a new formatter with the specified file name, charset, and locale.
Parameters:
fileName - The name of the file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn - The name of a supported
charset
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Throws:
FileNotFoundException
- If the given file name does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException
- If a security manager is present and
checkWrite(fileName)
denies write access to the file
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public
Formatter
(
File
file)
throws
FileNotFoundException
Constructs a new formatter with the specified file.
The charset used is the
default charset
for this instance of the Java virtual machine.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
file - The file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
Throws:
SecurityException
- If a security manager is present and
checkWrite(file.getPath())
denies write access to the file
FileNotFoundException
- If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
Formatter
public
Formatter
(
File
file,
String
csn)
throws
FileNotFoundException
,
UnsupportedEncodingException
Constructs a new formatter with the specified file and charset.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
file - The file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn - The name of a supported
charset
Throws:
FileNotFoundException
- If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException
- If a security manager is present and
checkWrite(file.getPath())
denies write access to the file
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public
Formatter
(
File
file,
String
csn,
Locale
l)
throws
FileNotFoundException
,
UnsupportedEncodingException
Constructs a new formatter with the specified file, charset, and locale.
Parameters:
file - The file to use as the destination of this formatter. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn - The name of a supported
charset
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Throws:
FileNotFoundException
- If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException
- If a security manager is present and
checkWrite(file.getPath())
denies write access to the file
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public
Formatter
(
PrintStream
ps)
Constructs a new formatter with the specified print stream.
The locale used is the
default locale
for this instance of the Java virtual machine.
Characters are written to the given
PrintStream
object and are therefore encoded using that object's charset.
Formatter
public
Formatter
(
OutputStream
os)
Constructs a new formatter with the specified output stream.
The charset used is the
default charset
for this instance of the Java virtual machine.
The locale used is the
default locale
for this instance of the Java virtual machine.
Formatter
public
Formatter
(
OutputStream
os,
String
csn)
throws
UnsupportedEncodingException
Constructs a new formatter with the specified output stream and charset.
The locale used is the
default locale
for this instance of the Java virtual machine.
Parameters:
os - The output stream to use as the destination of this formatter. The output will be buffered.
csn - The name of a supported
charset
Throws:
UnsupportedEncodingException
- If the named charset is not supported
Formatter
public
Formatter
(
OutputStream
os,
String
csn,
Locale
l)
throws
UnsupportedEncodingException
Constructs a new formatter with the specified output stream, charset, and locale.
Parameters:
os - The output stream to use as the destination of this formatter. The output will be buffered.
csn - The name of a supported
charset
l - The
locale
to apply during formatting. If
l
is
null
then no localization is applied.
Throws:
UnsupportedEncodingException
- If the named charset is not supported
Method Detail
locale
public Locale locale()
out
public Appendable out()
toString
public String toString()
Formatter f = new Formatter();
f.format("Last reboot at %tc", lastRebootDate);
String s = f.toString();
//
->
-> s == "Last reboot at Sat Jan 01 00:00:00 PST 2000"
out().toString()
flush
public void flush()
close
public void close()
ioException
public IOException ioException()
format
public Formatter format(String format,
Object... args)
format
public Formatter format(Locale l,
String format,
Object... args)