Serializable
, Cloneable
ChoiceFormat
, CompactNumberFormat
, DecimalFormat
public abstract class NumberFormat extends Format
NumberFormat
is the abstract base class for all number formats. This class provides the interface for formatting and parsing numbers. NumberFormat
also provides methods for determining which locales have number formats, and what their names are. NumberFormat
helps you to format and parse numbers for any locale. Your code can be completely independent of the locale conventions for decimal points, thousands-separators, or even the particular decimal digits used, or whether the number format is even decimal.
To format a number for the current Locale, use one of the factory class methods:
If you are formatting multiple numbers, it is more efficient to get the format and use it multiple times so that the system doesn't have to fetch the information about the local language and country conventions multiple times.myString = NumberFormat.getInstance().format(myNumber);
To format a number for a different Locale, specify it in the call toNumberFormat nf = NumberFormat.getInstance(); for (int i = 0; i < myNumber.length; ++i) { output.println(nf.format(myNumber[i]) + "; "); }
getInstance
. NumberFormat nf = NumberFormat.getInstance(Locale.FRENCH);
If the locale contains "nu" (numbers) and/or "rg" (region override) Unicode extensions, the decimal digits, and/or the country used for formatting are overridden. If both "nu" and "rg" are specified, the decimal digits from the "nu" extension supersedes the implicit one from the "rg" extension.
You can also use a NumberFormat
to parse numbers:
UsemyNumber = nf.parse(myString);
getInstance
or getNumberInstance
to get the normal number format. Use getIntegerInstance
to get an integer number format. Use getCurrencyInstance
to get the currency number format. Use getCompactNumberInstance
to get the compact number format to format a number in shorter form. For example, 2000
can be formatted as "2K"
in US locale
. Use getPercentInstance
to get a format for displaying percentages. With this format, a fraction like 0.53 is displayed as 53%. You can also control the display of numbers with such methods as setMinimumFractionDigits
. If you want even more control over the format or parsing, or want to give your users more control, you can try casting the NumberFormat
you get from the factory methods to a DecimalFormat
or CompactNumberFormat
depending on the factory method used. This will work for the vast majority of locales; just remember to put it in a try
block in case you encounter an unusual one.
NumberFormat and DecimalFormat are designed such that some controls work for formatting and others work for parsing. The following is the detailed description for each these control methods,
setParseIntegerOnly : only affects parsing, e.g. if true, "3456.78" → 3456 (and leaves the parse position just after index 6) if false, "3456.78" → 3456.78 (and leaves the parse position just after index 8) This is independent of formatting. If you want to not show a decimal point where there might be no digits after the decimal point, use setDecimalSeparatorAlwaysShown.
setDecimalSeparatorAlwaysShown : only affects formatting, and only where there might be no digits after the decimal point, such as with a pattern like "#,##0.##", e.g., if true, 3456.00 → "3,456." if false, 3456.00 → "3456" This is independent of parsing. If you want parsing to stop at the decimal point, use setParseIntegerOnly.
You can also use forms of the parse
and format
methods with ParsePosition
and FieldPosition
to allow you to:
FieldPosition
in your format call, with field
= INTEGER_FIELD
. On output, getEndIndex
will be set to the offset between the last character of the integer and the decimal. Add (desiredSpaceCount - getEndIndex) spaces at the front of the string. getEndIndex
. Then move the pen by (desiredPixelWidth - widthToAlignmentPoint) before drawing the text. It also works where there is no decimal, but possibly additional characters at the end, e.g., with parentheses in negative numbers: "(12)" for -12. Number 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.
format(double, StringBuffer, FieldPosition)
, format(long, StringBuffer, FieldPosition)
and parse(String, ParsePosition)
methods may throw NullPointerException
, if any of their parameter is null
. The subclass may provide its own implementation and specification about NullPointerException
. The default implementation provides rounding modes defined in RoundingMode
for formatting numbers. It uses the round half-even algorithm. To change the rounding mode use setRoundingMode
. The NumberFormat
returned by the static factory methods is configured to round floating point numbers using half-even rounding (see RoundingMode.HALF_EVEN
) for formatting.
Modifier and Type | Class | Description |
---|---|---|
static class |
NumberFormat.Field |
Defines constants that are used as attribute keys in the AttributedCharacterIterator returned from NumberFormat.formatToCharacterIterator and as field identifiers in FieldPosition . |
static enum |
NumberFormat.Style |
A number format style. |
Modifier and Type | Field | Description |
---|---|---|
static final int |
FRACTION_FIELD |
Field constant used to construct a FieldPosition object. |
static final int |
INTEGER_FIELD |
Field constant used to construct a FieldPosition object. |
Modifier | Constructor | Description |
---|---|---|
protected |
Sole constructor. |
Modifier and Type | Method | Description |
---|---|---|
Object |
clone() |
Overrides Cloneable. |
boolean |
equals |
Overrides equals. |
final String |
format |
Specialization of format. |
abstract StringBuffer |
format |
Specialization of format. |
final String |
format |
Specialization of format. |
abstract StringBuffer |
format |
Specialization of format. |
StringBuffer |
format |
Formats a number and appends the resulting text to the given string buffer. |
static Locale[] |
getAvailableLocales() |
Returns an array of all locales for which the get*Instance methods of this class can return localized instances. |
static NumberFormat |
getCompactNumberInstance() |
|
static NumberFormat |
getCompactNumberInstance |
Returns a compact number format for the specified locale and formatStyle . |
Currency |
getCurrency() |
Gets the currency used by this number format when formatting currency values. |
static final NumberFormat |
getCurrencyInstance() |
Returns a currency format for the current default FORMAT locale. |
static NumberFormat |
getCurrencyInstance |
Returns a currency format for the specified locale. |
static final NumberFormat |
getInstance() |
Returns a general-purpose number format for the current default FORMAT locale. |
static NumberFormat |
getInstance |
Returns a general-purpose number format for the specified locale. |
static final NumberFormat |
getIntegerInstance() |
Returns an integer number format for the current default FORMAT locale. |
static NumberFormat |
getIntegerInstance |
Returns an integer number format for the specified locale. |
int |
getMaximumFractionDigits() |
Returns the maximum number of digits allowed in the fraction portion of a number. |
int |
getMaximumIntegerDigits() |
Returns the maximum number of digits allowed in the integer portion of a number. |
int |
getMinimumFractionDigits() |
Returns the minimum number of digits allowed in the fraction portion of a number. |
int |
getMinimumIntegerDigits() |
Returns the minimum number of digits allowed in the integer portion of a number. |
static final NumberFormat |
getNumberInstance() |
Returns a general-purpose number format for the current default FORMAT locale. |
static NumberFormat |
getNumberInstance |
Returns a general-purpose number format for the specified locale. |
static final NumberFormat |
getPercentInstance() |
Returns a percentage format for the current default FORMAT locale. |
static NumberFormat |
getPercentInstance |
Returns a percentage format for the specified locale. |
RoundingMode |
getRoundingMode() |
Gets the RoundingMode used in this NumberFormat. |
int |
hashCode() |
Overrides hashCode. |
boolean |
isGroupingUsed() |
Returns true if grouping is used in this format. |
boolean |
isParseIntegerOnly() |
Returns true if this format will parse numbers as integers only. |
Number |
parse |
Parses text from the beginning of the given string to produce a number. |
abstract Number |
parse |
Returns a Long if possible (e.g., within the range [Long.MIN_VALUE, Long.MAX_VALUE] and with no decimals), otherwise a Double. |
final Object |
parseObject |
Parses text from a string to produce a Number . |
void |
setCurrency |
Sets the currency used by this number format when formatting currency values. |
void |
setGroupingUsed |
Set whether or not grouping will be used in this format. |
void |
setMaximumFractionDigits |
Sets the maximum number of digits allowed in the fraction portion of a number. maximumFractionDigits must be ≥ minimumFractionDigits. |
void |
setMaximumIntegerDigits |
Sets the maximum number of digits allowed in the integer portion of a number. maximumIntegerDigits must be ≥ minimumIntegerDigits. |
void |
setMinimumFractionDigits |
Sets the minimum number of digits allowed in the fraction portion of a number. minimumFractionDigits must be ≤ maximumFractionDigits. |
void |
setMinimumIntegerDigits |
Sets the minimum number of digits allowed in the integer portion of a number. minimumIntegerDigits must be ≤ maximumIntegerDigits. |
void |
setParseIntegerOnly |
Sets whether or not numbers should be parsed as integers only. |
void |
setRoundingMode |
Sets the RoundingMode used in this NumberFormat. |
format, formatToCharacterIterator, parseObject
public static final int INTEGER_FIELD
public static final int FRACTION_FIELD
protected NumberFormat()
public StringBuffer format(Object number, StringBuffer toAppendTo, FieldPosition pos)
Number
. This implementation extracts the number's value using Number.longValue()
for all integral type values that can be converted to long
without loss of information, including BigInteger
values with a bit length
of less than 64, and Number.doubleValue()
for all other types. It then calls format(long,java.lang.StringBuffer,java.text.FieldPosition)
or format(double,java.lang.StringBuffer,java.text.FieldPosition)
. This may result in loss of magnitude information and precision for BigInteger
and BigDecimal
values.
format
in class Format
number
- the number to formattoAppendTo
- the StringBuffer
to which the formatted text is to be appendedpos
- keeps track on the position of the field within the returned string. For example, for formatting a number 1234567.89
in Locale.US
locale, if the given fieldPosition
is INTEGER_FIELD
, the begin index and end index of fieldPosition
will be set to 0 and 9, respectively for the output string 1,234,567.89
.toAppendTo
IllegalArgumentException
- if number
is null or not an instance of Number
.NullPointerException
- if toAppendTo
or pos
is nullArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARYpublic final Object parseObject(String source, ParsePosition pos)
Number
. The method attempts to parse text starting at the index given by pos
. If parsing succeeds, then the index of pos
is updated to the index after the last character used (parsing does not necessarily use all characters up to the end of the string), and the parsed number is returned. The updated pos
can be used to indicate the starting point for the next call to this method. If an error occurs, then the index of pos
is not changed, the error index of pos
is set to the index of the character where the error occurred, and null is returned.
See the parse(String, ParsePosition)
method for more information on number parsing.
parseObject
in class Format
source
- A String
, part of which should be parsed.pos
- A ParsePosition
object with index and error index information as described above.Number
parsed from the string. In case of error, returns null.NullPointerException
- if source
or pos
is null.public final String format(double number)
number
- the double number to formatArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARYpublic final String format(long number)
number
- the long number to formatArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARYpublic abstract StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition pos)
number
- the double number to formattoAppendTo
- the StringBuffer to which the formatted text is to be appendedpos
- keeps track on the position of the field within the returned string. For example, for formatting a number 1234567.89
in Locale.US
locale, if the given fieldPosition
is INTEGER_FIELD
, the begin index and end index of fieldPosition
will be set to 0 and 9, respectively for the output string 1,234,567.89
.ArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARYpublic abstract StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition pos)
number
- the long number to formattoAppendTo
- the StringBuffer to which the formatted text is to be appendedpos
- keeps track on the position of the field within the returned string. For example, for formatting a number 123456789
in Locale.US
locale, if the given fieldPosition
is INTEGER_FIELD
, the begin index and end index of fieldPosition
will be set to 0 and 11, respectively for the output string 123,456,789
.ArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARYpublic abstract Number parse(String source, ParsePosition parsePosition)
source
- the String to parseparsePosition
- the parse positionpublic Number parse(String source) throws ParseException
See the parse(String, ParsePosition)
method for more information on number parsing.
source
- A String
whose beginning should be parsed.Number
parsed from the string.ParseException
- if the beginning of the specified string cannot be parsed.public boolean isParseIntegerOnly()
true
if numbers should be parsed as integers only; false
otherwisepublic void setParseIntegerOnly(boolean value)
value
- true
if numbers should be parsed as integers only; false
otherwisepublic static final NumberFormat getInstance()
FORMAT
locale. This is the same as calling getNumberInstance()
.NumberFormat
instance for general-purpose number formattingpublic static NumberFormat getInstance(Locale inLocale)
getNumberInstance(inLocale)
.inLocale
- the desired localeNumberFormat
instance for general-purpose number formattingpublic static final NumberFormat getNumberInstance()
FORMAT
locale. This is equivalent to calling getNumberInstance(Locale.getDefault(Locale.Category.FORMAT))
.
NumberFormat
instance for general-purpose number formattingpublic static NumberFormat getNumberInstance(Locale inLocale)
inLocale
- the desired localeNumberFormat
instance for general-purpose number formattingpublic static final NumberFormat getIntegerInstance()
FORMAT
locale. The returned number format is configured to round floating point numbers to the nearest integer using half-even rounding (see RoundingMode.HALF_EVEN
) for formatting, and to parse only the integer part of an input string (see isParseIntegerOnly
). This is equivalent to calling getIntegerInstance(Locale.getDefault(Locale.Category.FORMAT))
.
public static NumberFormat getIntegerInstance(Locale inLocale)
RoundingMode.HALF_EVEN
) for formatting, and to parse only the integer part of an input string (see isParseIntegerOnly
).inLocale
- the desired localepublic static final NumberFormat getCurrencyInstance()
FORMAT
locale. This is equivalent to calling getCurrencyInstance(Locale.getDefault(Locale.Category.FORMAT))
.
NumberFormat
instance for currency formattingpublic static NumberFormat getCurrencyInstance(Locale inLocale)
If the specified locale contains the "cf
" ( currency format style) Unicode extension, the returned currency format uses the style if it is available. Otherwise, the style uses the default "standard
" currency format. For example, if the style designates "account
", negative currency amounts use a pair of parentheses in some locales.
inLocale
- the desired localeNumberFormat
instance for currency formattingpublic static final NumberFormat getPercentInstance()
FORMAT
locale. This is equivalent to calling getPercentInstance(Locale.getDefault(Locale.Category.FORMAT))
.
NumberFormat
instance for percentage formattingpublic static NumberFormat getPercentInstance(Locale inLocale)
inLocale
- the desired localeNumberFormat
instance for percentage formattingpublic static NumberFormat getCompactNumberInstance()
NumberFormat
instance for compact number formattingpublic static NumberFormat getCompactNumberInstance(Locale locale, NumberFormat.Style formatStyle)
locale
and formatStyle
.locale
- the desired localeformatStyle
- the style for formatting a numberNumberFormat
instance for compact number formattingNullPointerException
- if locale
or formatStyle
is null
public static Locale[] getAvailableLocales()
get*Instance
methods of this class can return localized instances. The returned array represents the union of locales supported by the Java runtime and by installed NumberFormatProvider
implementations. At a minimum, the returned array must contain a Locale
instance equal to Locale.ROOT
and a Locale
instance equal to Locale.US
.NumberFormat
instances are available.public int hashCode()
public boolean equals(Object obj)
public Object clone()
public boolean isGroupingUsed()
true
if grouping is used; false
otherwisepublic void setGroupingUsed(boolean newValue)
newValue
- true
if grouping is used; false
otherwisepublic int getMaximumIntegerDigits()
public void setMaximumIntegerDigits(int newValue)
newValue
- the maximum number of integer digits to be shown; if less than zero, then zero is used. The concrete subclass may enforce an upper limit to this value appropriate to the numeric type being formatted.public int getMinimumIntegerDigits()
public void setMinimumIntegerDigits(int newValue)
newValue
- the minimum number of integer digits to be shown; if less than zero, then zero is used. The concrete subclass may enforce an upper limit to this value appropriate to the numeric type being formatted.public int getMaximumFractionDigits()
public void setMaximumFractionDigits(int newValue)
newValue
- the maximum number of fraction digits to be shown; if less than zero, then zero is used. The concrete subclass may enforce an upper limit to this value appropriate to the numeric type being formatted.public int getMinimumFractionDigits()
public void setMinimumFractionDigits(int newValue)
newValue
- the minimum number of fraction digits to be shown; if less than zero, then zero is used. The concrete subclass may enforce an upper limit to this value appropriate to the numeric type being formatted.public Currency getCurrency()
setCurrency
. The default implementation throws UnsupportedOperationException
.
null
UnsupportedOperationException
- if the number format class doesn't implement currency formattingpublic void setCurrency(Currency currency)
The default implementation throws UnsupportedOperationException
.
currency
- the new currency to be used by this number formatUnsupportedOperationException
- if the number format class doesn't implement currency formattingNullPointerException
- if currency
is nullpublic RoundingMode getRoundingMode()
RoundingMode
used in this NumberFormat. The default implementation of this method in NumberFormat always throws UnsupportedOperationException
. Subclasses which handle different rounding modes should override this method.RoundingMode
used for this NumberFormat.UnsupportedOperationException
- The default implementation always throws this exceptionpublic void setRoundingMode(RoundingMode roundingMode)
RoundingMode
used in this NumberFormat. The default implementation of this method in NumberFormat always throws UnsupportedOperationException
. Subclasses which handle different rounding modes should override this method.roundingMode
- The RoundingMode
to be usedUnsupportedOperationException
- The default implementation always throws this exceptionNullPointerException
- if roundingMode
is null
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