jdk.text.DecimalFormat

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DecimalFormat is a concrete subclass of NumberFormat that formats decimal numbers. It has a variety of features designed to make it possible to parse and format numbers in any locale, including support for Western, Arabic, and Indic digits. It also supports different kinds of numbers, including integers (123), fixed-point numbers (123.4), scientific notation (1.23E4), percentages (12%), and currency amounts ($123). All of these can be localized.

To obtain a NumberFormat for a specific locale, including the default locale, call one of NumberFormat's factory methods, such as getInstance(). In general, do not call the DecimalFormat constructors directly, since the NumberFormat factory methods may return subclasses other than DecimalFormat. If you need to customize the format object, do something like this:

NumberFormat f = NumberFormat.getInstance(loc); if (f instanceof DecimalFormat) { ((DecimalFormat) f).setDecimalSeparatorAlwaysShown(true); }

A DecimalFormat comprises a pattern and a set of symbols. The pattern may be set directly using applyPattern(), or indirectly using the API methods. The symbols are stored in a DecimalFormatSymbols object. When using the NumberFormat factory methods, the pattern and symbols are read from localized ResourceBundles.

Patterns

DecimalFormat patterns have the following syntax:

Pattern: PositivePattern PositivePattern ; NegativePattern PositivePattern: Prefixopt Number Suffixopt NegativePattern: Prefixopt Number Suffixopt Prefix: any Unicode characters except \uFFFE, \uFFFF, and special characters Suffix: any Unicode characters except \uFFFE, \uFFFF, and special characters Number: Integer Exponentopt Integer . Fraction Exponentopt Integer: MinimumInteger # # Integer # , Integer MinimumInteger: 0 0 MinimumInteger 0 , MinimumInteger Fraction: MinimumFractionopt OptionalFractionopt MinimumFraction: 0 MinimumFractionopt OptionalFraction: # OptionalFractionopt Exponent: E MinimumExponent MinimumExponent: 0 MinimumExponentopt

A DecimalFormat pattern contains a positive and negative subpattern, for example, "#,##0.00;(#,##0.00)". Each subpattern has a prefix, numeric part, and suffix. The negative subpattern is optional; if absent, then the positive subpattern prefixed with the localized minus sign ('-' in most locales) is used as the negative subpattern. That is, "0.00" alone is equivalent to "0.00;-0.00". If there is an explicit negative subpattern, it serves only to specify the negative prefix and suffix; the number of digits, minimal digits, and other characteristics are all the same as the positive pattern. That means that "#,##0.0#;(#)" produces precisely the same behavior as "#,##0.0#;(#,##0.0#)".

The prefixes, suffixes, and various symbols used for infinity, digits, thousands separators, decimal separators, etc. may be set to arbitrary values, and they will appear properly during formatting. However, care must be taken that the symbols and strings do not conflict, or parsing will be unreliable. For example, either the positive and negative prefixes or the suffixes must be distinct for DecimalFormat.parse() to be able to distinguish positive from negative values. (If they are identical, then DecimalFormat will behave as if no negative subpattern was specified.) Another example is that the decimal separator and thousands separator should be distinct characters, or parsing will be impossible.

The grouping separator is commonly used for thousands, but in some countries it separates ten-thousands. The grouping size is a constant number of digits between the grouping characters, such as 3 for 100,000,000 or 4 for 1,0000,0000. If you supply a pattern with multiple grouping characters, the interval between the last one and the end of the integer is the one that is used. So "#,##,###,####" == "######,####" == "##,####,####".

Special Pattern Characters

Many characters in a pattern are taken literally; they are matched during parsing and output unchanged during formatting. Special characters, on the other hand, stand for other characters, strings, or classes of characters. They must be quoted, unless noted otherwise, if they are to appear in the prefix or suffix as literals.

The characters listed here are used in non-localized patterns. Localized patterns use the corresponding characters taken from this formatter's DecimalFormatSymbols object instead, and these characters lose their special status. Two exceptions are the currency sign and quote, which are not localized.

     Symbol
     Location
     Localized?
     Meaning

     0
     Number
     Yes
     Digit

     #
     Number
     Yes
     Digit, zero shows as absent

     .
     Number
     Yes
     Decimal separator or monetary decimal separator

     -
     Number
     Yes
     Minus sign

     ,
     Number
     Yes
     Grouping separator

     E
     Number
     Yes
     Separates mantissa and exponent in scientific notation.
         Need not be quoted in prefix or suffix.

     ;
     Subpattern boundary
     Yes
     Separates positive and negative subpatterns

     %
     Prefix or suffix
     Yes
     Multiply by 100 and show as percentage

     \u2030
     Prefix or suffix
     Yes
     Multiply by 1000 and show as per mille value

     ¤ (\u00A4)
     Prefix or suffix
     No
     Currency sign, replaced by currency symbol.  If
         doubled, replaced by international currency symbol.
         If present in a pattern, the monetary decimal separator
         is used instead of the decimal separator.

     '
     Prefix or suffix
     No
     Used to quote special characters in a prefix or suffix,
         for example, "'#'#" formats 123 to
         "#123".  To create a single quote
         itself, use two in a row: "# o''clock".

Scientific Notation

Numbers in scientific notation are expressed as the product of a mantissa and a power of ten, for example, 1234 can be expressed as 1.234 x 10^3. The mantissa is often in the range 1.0 ≤ x < 10.0, but it need not be. DecimalFormat can be instructed to format and parse scientific notation only via a pattern; there is currently no factory method that creates a scientific notation format. In a pattern, the exponent character immediately followed by one or more digit characters indicates scientific notation. Example: "0.###E0" formats the number 1234 as "1.234E3".

The number of digit characters after the exponent character gives the minimum exponent digit count. There is no maximum. Negative exponents are formatted using the localized minus sign, not the prefix and suffix from the pattern. This allows patterns such as "0.###E0 m/s".

The minimum and maximum number of integer digits are interpreted together:

If the maximum number of integer digits is greater than their minimum number and greater than 1, it forces the exponent to be a multiple of the maximum number of integer digits, and the minimum number of integer digits to be interpreted as 1. The most common use of this is to generate engineering notation, in which the exponent is a multiple of three, e.g., "##0.#####E0". Using this pattern, the number 12345 formats to "12.345E3", and 123456 formats to "123.456E3".

Otherwise, the minimum number of integer digits is achieved by adjusting the exponent. Example: 0.00123 formatted with "00.###E0" yields "12.3E-4".

The number of significant digits in the mantissa is the sum of the minimum integer and maximum fraction digits, and is unaffected by the maximum integer digits. For example, 12345 formatted with "##0.##E0" is "12.3E3". To show all digits, set the significant digits count to zero. The number of significant digits does not affect parsing.

Exponential patterns may not contain grouping separators.

Rounding

DecimalFormat provides rounding modes defined in RoundingMode for formatting. By default, it uses RoundingMode.HALF_EVEN.

Digits

For formatting, DecimalFormat uses the ten consecutive characters starting with the localized zero digit defined in the DecimalFormatSymbols object as digits. For parsing, these digits as well as all Unicode decimal digits, as defined by Character.digit, are recognized.

Special Values

NaN is formatted as a string, which typically has a single character \uFFFD. This string is determined by the DecimalFormatSymbols object. This is the only value for which the prefixes and suffixes are not used.

Infinity is formatted as a string, which typically has a single character \u221E, with the positive or negative prefixes and suffixes applied. The infinity string is determined by the DecimalFormatSymbols object.

Negative zero ("-0") parses to

BigDecimal(0) if isParseBigDecimal() is true, Long(0) if isParseBigDecimal() is false and isParseIntegerOnly() is true, Double(-0.0) if both isParseBigDecimal() and isParseIntegerOnly() are false.

Synchronization

Decimal formats are generally not synchronized. It is recommended to create separate format instances for each thread. If multiple threads access a format concurrently, it must be synchronized externally.

Example

<strong>// Print out a number using the localized number, integer, currency, // and percent format for each locale</strong> Locale[] locales = NumberFormat.getAvailableLocales(); double myNumber = -1234.56; NumberFormat form; for (int j = 0; j < 4; +j) { System.out.println("FORMAT"); for (int i = 0; i < locales.length; +i) { if (locales[i].getCountry().length() == 0) { continue; // Skip language-only locales } System.out.print(locales[i].getDisplayName()); switch (j) { case 0: form = NumberFormat.getInstance(locales[i]); break; case 1: form = NumberFormat.getIntegerInstance(locales[i]); break; case 2: form = NumberFormat.getCurrencyInstance(locales[i]); break; default: form = NumberFormat.getPercentInstance(locales[i]); break; } if (form instanceof DecimalFormat) { System.out.print(": " ((DecimalFormat) form).toPattern()); } System.out.print(" -> " form.format(myNumber)); try { System.out.println(" -> " form.parse(form.format(myNumber))); } catch (ParseException e) {} } }

DecimalFormat is a concrete subclass of
NumberFormat that formats decimal numbers. It has a variety of
features designed to make it possible to parse and format numbers in any
locale, including support for Western, Arabic, and Indic digits.  It also
supports different kinds of numbers, including integers (123), fixed-point
numbers (123.4), scientific notation (1.23E4), percentages (12%), and
currency amounts ($123).  All of these can be localized.

To obtain a NumberFormat for a specific locale, including the
default locale, call one of NumberFormat's factory methods, such
as getInstance().  In general, do not call the
DecimalFormat constructors directly, since the
NumberFormat factory methods may return subclasses other than
DecimalFormat. If you need to customize the format object, do
something like this:



NumberFormat f = NumberFormat.getInstance(loc);
if (f instanceof DecimalFormat) {
    ((DecimalFormat) f).setDecimalSeparatorAlwaysShown(true);
}

A DecimalFormat comprises a pattern and a set of
symbols.  The pattern may be set directly using
applyPattern(), or indirectly using the API methods.  The
symbols are stored in a DecimalFormatSymbols object.  When using
the NumberFormat factory methods, the pattern and symbols are
read from localized ResourceBundles.

Patterns

DecimalFormat patterns have the following syntax:


Pattern:
        PositivePattern
        PositivePattern ; NegativePattern
PositivePattern:
        Prefixopt Number Suffixopt
NegativePattern:
        Prefixopt Number Suffixopt
Prefix:
        any Unicode characters except \uFFFE, \uFFFF, and special characters
Suffix:
        any Unicode characters except \uFFFE, \uFFFF, and special characters
Number:
        Integer Exponentopt
        Integer . Fraction Exponentopt
Integer:
        MinimumInteger
        #
        # Integer
        # , Integer
MinimumInteger:
        0
        0 MinimumInteger
        0 , MinimumInteger
Fraction:
        MinimumFractionopt OptionalFractionopt
MinimumFraction:
        0 MinimumFractionopt
OptionalFraction:
        # OptionalFractionopt
Exponent:
        E MinimumExponent
MinimumExponent:
        0 MinimumExponentopt

A DecimalFormat pattern contains a positive and negative
subpattern, for example, "#,##0.00;(#,##0.00)".  Each
subpattern has a prefix, numeric part, and suffix. The negative subpattern
is optional; if absent, then the positive subpattern prefixed with the
localized minus sign ('-' in most locales) is used as the
negative subpattern. That is, "0.00" alone is equivalent to
"0.00;-0.00".  If there is an explicit negative subpattern, it
serves only to specify the negative prefix and suffix; the number of digits,
minimal digits, and other characteristics are all the same as the positive
pattern. That means that "#,##0.0#;(#)" produces precisely
the same behavior as "#,##0.0#;(#,##0.0#)".

The prefixes, suffixes, and various symbols used for infinity, digits,
thousands separators, decimal separators, etc. may be set to arbitrary
values, and they will appear properly during formatting.  However, care must
be taken that the symbols and strings do not conflict, or parsing will be
unreliable.  For example, either the positive and negative prefixes or the
suffixes must be distinct for DecimalFormat.parse() to be able
to distinguish positive from negative values.  (If they are identical, then
DecimalFormat will behave as if no negative subpattern was
specified.)  Another example is that the decimal separator and thousands
separator should be distinct characters, or parsing will be impossible.

The grouping separator is commonly used for thousands, but in some
countries it separates ten-thousands. The grouping size is a constant number
of digits between the grouping characters, such as 3 for 100,000,000 or 4 for
1,0000,0000.  If you supply a pattern with multiple grouping characters, the
interval between the last one and the end of the integer is the one that is
used. So "#,##,###,####" == "######,####" ==
"##,####,####".

Special Pattern Characters

Many characters in a pattern are taken literally; they are matched during
parsing and output unchanged during formatting.  Special characters, on the
other hand, stand for other characters, strings, or classes of characters.
They must be quoted, unless noted otherwise, if they are to appear in the
prefix or suffix as literals.

The characters listed here are used in non-localized patterns.  Localized
patterns use the corresponding characters taken from this formatter's
DecimalFormatSymbols object instead, and these characters lose
their special status.  Two exceptions are the currency sign and quote, which
are not localized.




         Symbol
         Location
         Localized?
         Meaning

         0
         Number
         Yes
         Digit

         #
         Number
         Yes
         Digit, zero shows as absent

         .
         Number
         Yes
         Decimal separator or monetary decimal separator

         -
         Number
         Yes
         Minus sign

         ,
         Number
         Yes
         Grouping separator

         E
         Number
         Yes
         Separates mantissa and exponent in scientific notation.
             Need not be quoted in prefix or suffix.

         ;
         Subpattern boundary
         Yes
         Separates positive and negative subpatterns

         %
         Prefix or suffix
         Yes
         Multiply by 100 and show as percentage

         \u2030
         Prefix or suffix
         Yes
         Multiply by 1000 and show as per mille value

         ¤ (\u00A4)
         Prefix or suffix
         No
         Currency sign, replaced by currency symbol.  If
             doubled, replaced by international currency symbol.
             If present in a pattern, the monetary decimal separator
             is used instead of the decimal separator.

         '
         Prefix or suffix
         No
         Used to quote special characters in a prefix or suffix,
             for example, "'#'#" formats 123 to
             "#123".  To create a single quote
             itself, use two in a row: "# o''clock".



Scientific Notation

Numbers in scientific notation are expressed as the product of a mantissa
and a power of ten, for example, 1234 can be expressed as 1.234 x 10^3.  The
mantissa is often in the range 1.0 ≤ x < 10.0, but it need not
be.
DecimalFormat can be instructed to format and parse scientific
notation only via a pattern; there is currently no factory method
that creates a scientific notation format.  In a pattern, the exponent
character immediately followed by one or more digit characters indicates
scientific notation.  Example: "0.###E0" formats the number
1234 as "1.234E3".


The number of digit characters after the exponent character gives the
minimum exponent digit count.  There is no maximum.  Negative exponents are
formatted using the localized minus sign, not the prefix and suffix
from the pattern.  This allows patterns such as "0.###E0 m/s".

The minimum and maximum number of integer digits are interpreted
together:


If the maximum number of integer digits is greater than their minimum number
and greater than 1, it forces the exponent to be a multiple of the maximum
number of integer digits, and the minimum number of integer digits to be
interpreted as 1.  The most common use of this is to generate
engineering notation, in which the exponent is a multiple of three,
e.g., "##0.#####E0". Using this pattern, the number 12345
formats to "12.345E3", and 123456 formats to
"123.456E3".

Otherwise, the minimum number of integer digits is achieved by adjusting the
exponent.  Example: 0.00123 formatted with "00.###E0" yields
"12.3E-4".


The number of significant digits in the mantissa is the sum of the
minimum integer and maximum fraction digits, and is
unaffected by the maximum integer digits.  For example, 12345 formatted with
"##0.##E0" is "12.3E3". To show all digits, set
the significant digits count to zero.  The number of significant digits
does not affect parsing.

Exponential patterns may not contain grouping separators.


Rounding

DecimalFormat provides rounding modes defined in
RoundingMode for formatting.  By default, it uses
RoundingMode.HALF_EVEN.

Digits

For formatting, DecimalFormat uses the ten consecutive
characters starting with the localized zero digit defined in the
DecimalFormatSymbols object as digits. For parsing, these
digits as well as all Unicode decimal digits, as defined by
Character.digit, are recognized.

Special Values

NaN is formatted as a string, which typically has a single character
\uFFFD.  This string is determined by the
DecimalFormatSymbols object.  This is the only value for which
the prefixes and suffixes are not used.

Infinity is formatted as a string, which typically has a single character
\u221E, with the positive or negative prefixes and suffixes
applied.  The infinity string is determined by the
DecimalFormatSymbols object.

Negative zero ("-0") parses to

BigDecimal(0) if isParseBigDecimal() is
true,
Long(0) if isParseBigDecimal() is false
    and isParseIntegerOnly() is true,
Double(-0.0) if both isParseBigDecimal()
and isParseIntegerOnly() are false.


Synchronization


Decimal formats are generally not synchronized.
It is recommended to create separate format instances for each thread.
If multiple threads access a format concurrently, it must be synchronized
externally.

Example



<strong>// Print out a number using the localized number, integer, currency,
// and percent format for each locale</strong>
Locale[] locales = NumberFormat.getAvailableLocales();
double myNumber = -1234.56;
NumberFormat form;
for (int j = 0; j < 4; +j) {
    System.out.println("FORMAT");
    for (int i = 0; i < locales.length; +i) {
        if (locales[i].getCountry().length() == 0) {
           continue; // Skip language-only locales
        }
        System.out.print(locales[i].getDisplayName());
        switch (j) {
        case 0:
            form = NumberFormat.getInstance(locales[i]); break;
        case 1:
            form = NumberFormat.getIntegerInstance(locales[i]); break;
        case 2:
            form = NumberFormat.getCurrencyInstance(locales[i]); break;
        default:
            form = NumberFormat.getPercentInstance(locales[i]); break;
        }
        if (form instanceof DecimalFormat) {
            System.out.print(": "  ((DecimalFormat) form).toPattern());
        }
        System.out.print(" -> "  form.format(myNumber));
        try {
            System.out.println(" -> "  form.parse(form.format(myNumber)));
        } catch (ParseException e) {}
    }
}

jdk.text.DecimalFormat

->decimal-formatclj

apply-localized-patternclj

apply-patternclj

cloneclj

decimal-separator-always-shown?clj

equalsclj

formatclj

format-to-character-iteratorclj

get-currencyclj

get-decimal-format-symbolsclj

get-grouping-sizeclj

get-maximum-fraction-digitsclj

get-maximum-integer-digitsclj

get-minimum-fraction-digitsclj

get-minimum-integer-digitsclj

get-multiplierclj

get-negative-prefixclj

get-negative-suffixclj

get-positive-prefixclj

get-positive-suffixclj

get-rounding-modeclj

hash-codeclj

parseclj

parse-big-decimal?clj

set-currencyclj

set-decimal-format-symbolsclj

set-decimal-separator-always-shownclj

set-grouping-sizeclj

set-grouping-usedclj

set-maximum-fraction-digitsclj

set-maximum-integer-digitsclj

set-minimum-fraction-digitsclj

set-minimum-integer-digitsclj

set-multiplierclj

set-negative-prefixclj

set-negative-suffixclj

set-parse-big-decimalclj

set-positive-prefixclj

set-positive-suffixclj

set-rounding-modeclj

to-localized-patternclj

to-patternclj

->decimal-format^clj

apply-localized-pattern^clj

apply-pattern^clj

clone^clj

decimal-separator-always-shown?^clj

equals^clj

format^clj

format-to-character-iterator^clj

get-currency^clj

get-decimal-format-symbols^clj

get-grouping-size^clj

get-maximum-fraction-digits^clj

get-maximum-integer-digits^clj

get-minimum-fraction-digits^clj

get-minimum-integer-digits^clj

get-multiplier^clj

get-negative-prefix^clj

get-negative-suffix^clj

get-positive-prefix^clj

get-positive-suffix^clj

get-rounding-mode^clj

hash-code^clj

parse^clj

parse-big-decimal?^clj

set-currency^clj

set-decimal-format-symbols^clj

set-decimal-separator-always-shown^clj

set-grouping-size^clj

set-grouping-used^clj

set-maximum-fraction-digits^clj

set-maximum-integer-digits^clj

set-minimum-fraction-digits^clj

set-minimum-integer-digits^clj

set-multiplier^clj

set-negative-prefix^clj

set-negative-suffix^clj

set-parse-big-decimal^clj

set-positive-prefix^clj

set-positive-suffix^clj

set-rounding-mode^clj

to-localized-pattern^clj

to-pattern^clj