- java.lang.Object
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- java.text.Format
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- java.text.NumberFormat
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- All Implemented Interfaces:
Serializable,Cloneable
- Direct Known Subclasses:
ChoiceFormat,DecimalFormat
public abstract class NumberFormat extends Format
NumberFormatis the abstract base class for all number formats. This class provides the interface for formatting and parsing numbers.NumberFormatalso provides methods for determining which locales have number formats, and what their names are.NumberFormathelps 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
NumberFormatto parse numbers:
UsemyNumber = nf.parse(myString);getInstanceorgetNumberInstanceto get the normal number format. UsegetIntegerInstanceto get an integer number format. UsegetCurrencyInstanceto get the currency number format. And usegetPercentInstanceto 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 theNumberFormatyou get from the factory methods to aDecimalFormat. This will work for the vast majority of locales; just remember to put it in atryblock 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
parseandformatmethods withParsePositionandFieldPositionto allow you to:- progressively parse through pieces of a string
- align the decimal point and other areas
- If you are using a monospaced font with spacing for alignment,
you can pass the
FieldPositionin your format call, withfield=INTEGER_FIELD. On output,getEndIndexwill 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. - If you are using proportional fonts,
instead of padding with spaces, measure the width
of the string in pixels from the start to
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.
Synchronization
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.
- Implementation Requirements:
- The
format(double, StringBuffer, FieldPosition),format(long, StringBuffer, FieldPosition)andparse(String, ParsePosition)methods may throwNullPointerException, if any of their parameter isnull. The subclass may provide its own implementation and specification aboutNullPointerException.The default implementation provides rounding modes defined in
RoundingModefor formatting numbers. It uses the round half-even algorithm. To change the rounding mode usesetRoundingMode. TheNumberFormatreturned by the static factory methods is configured to round floating point numbers using half-even rounding (seeRoundingMode.HALF_EVEN) for formatting. - Since:
- 1.1
- See Also:
DecimalFormat,ChoiceFormat, Serialized Form
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Nested Class Summary
Nested Classes Modifier and Type Class Description static classNumberFormat.FieldDefines constants that are used as attribute keys in theAttributedCharacterIteratorreturned fromNumberFormat.formatToCharacterIteratorand as field identifiers inFieldPosition.
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Field Summary
Fields Modifier and Type Field Description static intFRACTION_FIELDField constant used to construct a FieldPosition object.static intINTEGER_FIELDField constant used to construct a FieldPosition object.
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Constructor Summary
Constructors Modifier Constructor Description protectedNumberFormat()Sole constructor.
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description Objectclone()Overrides Cloneable.booleanequals(Object obj)Overrides equals.Stringformat(double number)Specialization of format.abstract StringBufferformat(double number, StringBuffer toAppendTo, FieldPosition pos)Specialization of format.Stringformat(long number)Specialization of format.abstract StringBufferformat(long number, StringBuffer toAppendTo, FieldPosition pos)Specialization of format.StringBufferformat(Object number, StringBuffer toAppendTo, FieldPosition pos)Formats a number and appends the resulting text to the given string buffer.static Locale[]getAvailableLocales()Returns an array of all locales for which theget*Instancemethods of this class can return localized instances.CurrencygetCurrency()Gets the currency used by this number format when formatting currency values.static NumberFormatgetCurrencyInstance()Returns a currency format for the current defaultFORMATlocale.static NumberFormatgetCurrencyInstance(Locale inLocale)Returns a currency format for the specified locale.static NumberFormatgetInstance()Returns a general-purpose number format for the current defaultFORMATlocale.static NumberFormatgetInstance(Locale inLocale)Returns a general-purpose number format for the specified locale.static NumberFormatgetIntegerInstance()Returns an integer number format for the current defaultFORMATlocale.static NumberFormatgetIntegerInstance(Locale inLocale)Returns an integer number format for the specified locale.intgetMaximumFractionDigits()Returns the maximum number of digits allowed in the fraction portion of a number.intgetMaximumIntegerDigits()Returns the maximum number of digits allowed in the integer portion of a number.intgetMinimumFractionDigits()Returns the minimum number of digits allowed in the fraction portion of a number.intgetMinimumIntegerDigits()Returns the minimum number of digits allowed in the integer portion of a number.static NumberFormatgetNumberInstance()Returns a general-purpose number format for the current defaultFORMATlocale.static NumberFormatgetNumberInstance(Locale inLocale)Returns a general-purpose number format for the specified locale.static NumberFormatgetPercentInstance()Returns a percentage format for the current defaultFORMATlocale.static NumberFormatgetPercentInstance(Locale inLocale)Returns a percentage format for the specified locale.RoundingModegetRoundingMode()Gets theRoundingModeused in this NumberFormat.inthashCode()Overrides hashCode.booleanisGroupingUsed()Returns true if grouping is used in this format.booleanisParseIntegerOnly()Returns true if this format will parse numbers as integers only.Numberparse(String source)Parses text from the beginning of the given string to produce a number.abstract Numberparse(String source, ParsePosition parsePosition)Returns a Long if possible (e.g., within the range [Long.MIN_VALUE, Long.MAX_VALUE] and with no decimals), otherwise a Double.ObjectparseObject(String source, ParsePosition pos)Parses text from a string to produce aNumber.voidsetCurrency(Currency currency)Sets the currency used by this number format when formatting currency values.voidsetGroupingUsed(boolean newValue)Set whether or not grouping will be used in this format.voidsetMaximumFractionDigits(int newValue)Sets the maximum number of digits allowed in the fraction portion of a number. maximumFractionDigits must be ≥ minimumFractionDigits.voidsetMaximumIntegerDigits(int newValue)Sets the maximum number of digits allowed in the integer portion of a number. maximumIntegerDigits must be ≥ minimumIntegerDigits.voidsetMinimumFractionDigits(int newValue)Sets the minimum number of digits allowed in the fraction portion of a number. minimumFractionDigits must be ≤ maximumFractionDigits.voidsetMinimumIntegerDigits(int newValue)Sets the minimum number of digits allowed in the integer portion of a number. minimumIntegerDigits must be ≤ maximumIntegerDigits.voidsetParseIntegerOnly(boolean value)Sets whether or not numbers should be parsed as integers only.voidsetRoundingMode(RoundingMode roundingMode)Sets theRoundingModeused in this NumberFormat.-
Methods declared in class java.text.Format
format, formatToCharacterIterator, parseObject
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Field Detail
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INTEGER_FIELD
public static final int INTEGER_FIELD
Field constant used to construct a FieldPosition object. Signifies that the position of the integer part of a formatted number should be returned.- See Also:
FieldPosition, Constant Field Values
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FRACTION_FIELD
public static final int FRACTION_FIELD
Field constant used to construct a FieldPosition object. Signifies that the position of the fraction part of a formatted number should be returned.- See Also:
FieldPosition, Constant Field Values
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Method Detail
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format
public StringBuffer format(Object number, StringBuffer toAppendTo, FieldPosition pos)
Formats a number and appends the resulting text to the given string buffer. The number can be of any subclass ofNumber.This implementation extracts the number's value using
Number.longValue()for all integral type values that can be converted tolongwithout loss of information, includingBigIntegervalues with abit lengthof less than 64, andNumber.doubleValue()for all other types. It then callsformat(long,java.lang.StringBuffer,java.text.FieldPosition)orformat(double,java.lang.StringBuffer,java.text.FieldPosition). This may result in loss of magnitude information and precision forBigIntegerandBigDecimalvalues.- Specified by:
formatin classFormat- Parameters:
number- the number to formattoAppendTo- theStringBufferto 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 number1234567.89inLocale.USlocale, if the givenfieldPositionisINTEGER_FIELD, the begin index and end index offieldPositionwill be set to 0 and 9, respectively for the output string1,234,567.89.- Returns:
- the value passed in as
toAppendTo - Throws:
IllegalArgumentException- ifnumberis null or not an instance ofNumber.NullPointerException- iftoAppendToorposis nullArithmeticException- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
FieldPosition
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parseObject
public final Object parseObject(String source, ParsePosition pos)
Parses text from a string to produce aNumber.The method attempts to parse text starting at the index given by
pos. If parsing succeeds, then the index ofposis 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 updatedposcan be used to indicate the starting point for the next call to this method. If an error occurs, then the index ofposis not changed, the error index ofposis 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.- Specified by:
parseObjectin classFormat- Parameters:
source- AString, part of which should be parsed.pos- AParsePositionobject with index and error index information as described above.- Returns:
- A
Numberparsed from the string. In case of error, returns null. - Throws:
NullPointerException- ifsourceorposis null.
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format
public final String format(double number)
Specialization of format.- Parameters:
number- the double number to format- Returns:
- the formatted String
- Throws:
ArithmeticException- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
Format.format(java.lang.Object)
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format
public final String format(long number)
Specialization of format.- Parameters:
number- the long number to format- Returns:
- the formatted String
- Throws:
ArithmeticException- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
Format.format(java.lang.Object)
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format
public abstract StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition pos)
Specialization of format.- Parameters:
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 number1234567.89inLocale.USlocale, if the givenfieldPositionisINTEGER_FIELD, the begin index and end index offieldPositionwill be set to 0 and 9, respectively for the output string1,234,567.89.- Returns:
- the formatted StringBuffer
- Throws:
ArithmeticException- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
Format.format(java.lang.Object)
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format
public abstract StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition pos)
Specialization of format.- Parameters:
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 number123456789inLocale.USlocale, if the givenfieldPositionisINTEGER_FIELD, the begin index and end index offieldPositionwill be set to 0 and 11, respectively for the output string123,456,789.- Returns:
- the formatted StringBuffer
- Throws:
ArithmeticException- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
Format.format(java.lang.Object)
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parse
public abstract Number parse(String source, ParsePosition parsePosition)
Returns a Long if possible (e.g., within the range [Long.MIN_VALUE, Long.MAX_VALUE] and with no decimals), otherwise a Double. If IntegerOnly is set, will stop at a decimal point (or equivalent; e.g., for rational numbers "1 2/3", will stop after the 1). Does not throw an exception; if no object can be parsed, index is unchanged!- Parameters:
source- the String to parseparsePosition- the parse position- Returns:
- the parsed value
- See Also:
isParseIntegerOnly(),Format.parseObject(java.lang.String, java.text.ParsePosition)
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parse
public Number parse(String source) throws ParseException
Parses text from the beginning of the given string to produce a number. The method may not use the entire text of the given string.See the
parse(String, ParsePosition)method for more information on number parsing.- Parameters:
source- AStringwhose beginning should be parsed.- Returns:
- A
Numberparsed from the string. - Throws:
ParseException- if the beginning of the specified string cannot be parsed.
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isParseIntegerOnly
public boolean isParseIntegerOnly()
Returns true if this format will parse numbers as integers only. For example in the English locale, with ParseIntegerOnly true, the string "1234." would be parsed as the integer value 1234 and parsing would stop at the "." character. Of course, the exact format accepted by the parse operation is locale dependent and determined by sub-classes of NumberFormat.- Returns:
trueif numbers should be parsed as integers only;falseotherwise
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setParseIntegerOnly
public void setParseIntegerOnly(boolean value)
Sets whether or not numbers should be parsed as integers only.- Parameters:
value-trueif numbers should be parsed as integers only;falseotherwise- See Also:
isParseIntegerOnly()
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getInstance
public static final NumberFormat getInstance()
Returns a general-purpose number format for the current defaultFORMATlocale. This is the same as callinggetNumberInstance().- Returns:
- the
NumberFormatinstance for general-purpose number formatting
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getInstance
public static NumberFormat getInstance(Locale inLocale)
Returns a general-purpose number format for the specified locale. This is the same as callinggetNumberInstance(inLocale).- Parameters:
inLocale- the desired locale- Returns:
- the
NumberFormatinstance for general-purpose number formatting
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getNumberInstance
public static final NumberFormat getNumberInstance()
Returns a general-purpose number format for the current defaultFORMATlocale.This is equivalent to calling
getNumberInstance(Locale.getDefault(Locale.Category.FORMAT)).- Returns:
- the
NumberFormatinstance for general-purpose number formatting - See Also:
Locale.getDefault(java.util.Locale.Category),Locale.Category.FORMAT
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getNumberInstance
public static NumberFormat getNumberInstance(Locale inLocale)
Returns a general-purpose number format for the specified locale.- Parameters:
inLocale- the desired locale- Returns:
- the
NumberFormatinstance for general-purpose number formatting
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getIntegerInstance
public static final NumberFormat getIntegerInstance()
Returns an integer number format for the current defaultFORMATlocale. The returned number format is configured to round floating point numbers to the nearest integer using half-even rounding (seeRoundingMode.HALF_EVEN) for formatting, and to parse only the integer part of an input string (seeisParseIntegerOnly).This is equivalent to calling
getIntegerInstance(Locale.getDefault(Locale.Category.FORMAT)).- Returns:
- a number format for integer values
- Since:
- 1.4
- See Also:
getRoundingMode(),Locale.getDefault(java.util.Locale.Category),Locale.Category.FORMAT
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getIntegerInstance
public static NumberFormat getIntegerInstance(Locale inLocale)
Returns an integer number format for the specified locale. The returned number format is configured to round floating point numbers to the nearest integer using half-even rounding (seeRoundingMode.HALF_EVEN) for formatting, and to parse only the integer part of an input string (seeisParseIntegerOnly).- Parameters:
inLocale- the desired locale- Returns:
- a number format for integer values
- Since:
- 1.4
- See Also:
getRoundingMode()
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getCurrencyInstance
public static final NumberFormat getCurrencyInstance()
Returns a currency format for the current defaultFORMATlocale.This is equivalent to calling
getCurrencyInstance(Locale.getDefault(Locale.Category.FORMAT)).- Returns:
- the
NumberFormatinstance for currency formatting - See Also:
Locale.getDefault(java.util.Locale.Category),Locale.Category.FORMAT
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getCurrencyInstance
public static NumberFormat getCurrencyInstance(Locale inLocale)
Returns a currency format for the specified locale.- Parameters:
inLocale- the desired locale- Returns:
- the
NumberFormatinstance for currency formatting
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getPercentInstance
public static final NumberFormat getPercentInstance()
Returns a percentage format for the current defaultFORMATlocale.This is equivalent to calling
getPercentInstance(Locale.getDefault(Locale.Category.FORMAT)).- Returns:
- the
NumberFormatinstance for percentage formatting - See Also:
Locale.getDefault(java.util.Locale.Category),Locale.Category.FORMAT
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getPercentInstance
public static NumberFormat getPercentInstance(Locale inLocale)
Returns a percentage format for the specified locale.- Parameters:
inLocale- the desired locale- Returns:
- the
NumberFormatinstance for percentage formatting
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getAvailableLocales
public static Locale[] getAvailableLocales()
Returns an array of all locales for which theget*Instancemethods of this class can return localized instances. The returned array represents the union of locales supported by the Java runtime and by installedNumberFormatProviderimplementations. It must contain at least aLocaleinstance equal toLocale.US.- Returns:
- An array of locales for which localized
NumberFormatinstances are available.
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hashCode
public int hashCode()
Overrides hashCode.- Overrides:
hashCodein classObject- Returns:
- the receiver's hash.
- See Also:
Object.equals(java.lang.Object)
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equals
public boolean equals(Object obj)
Overrides equals.- Overrides:
equalsin classObject- Parameters:
obj- Object the object to compare with this object.- Returns:
- boolean
trueif the object is the same as this objectfalseif it is different from this object. - See Also:
Object.hashCode()
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clone
public Object clone()
Overrides Cloneable.
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isGroupingUsed
public boolean isGroupingUsed()
Returns true if grouping is used in this format. For example, in the English locale, with grouping on, the number 1234567 might be formatted as "1,234,567". The grouping separator as well as the size of each group is locale dependent and is determined by sub-classes of NumberFormat.- Returns:
trueif grouping is used;falseotherwise- See Also:
setGroupingUsed(boolean)
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setGroupingUsed
public void setGroupingUsed(boolean newValue)
Set whether or not grouping will be used in this format.- Parameters:
newValue-trueif grouping is used;falseotherwise- See Also:
isGroupingUsed()
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getMaximumIntegerDigits
public int getMaximumIntegerDigits()
Returns the maximum number of digits allowed in the integer portion of a number.- Returns:
- the maximum number of digits
- See Also:
setMaximumIntegerDigits(int)
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setMaximumIntegerDigits
public void setMaximumIntegerDigits(int newValue)
Sets the maximum number of digits allowed in the integer portion of a number. maximumIntegerDigits must be ≥ minimumIntegerDigits. If the new value for maximumIntegerDigits is less than the current value of minimumIntegerDigits, then minimumIntegerDigits will also be set to the new value.- Parameters:
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.- See Also:
getMaximumIntegerDigits()
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getMinimumIntegerDigits
public int getMinimumIntegerDigits()
Returns the minimum number of digits allowed in the integer portion of a number.- Returns:
- the minimum number of digits
- See Also:
setMinimumIntegerDigits(int)
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setMinimumIntegerDigits
public void setMinimumIntegerDigits(int newValue)
Sets the minimum number of digits allowed in the integer portion of a number. minimumIntegerDigits must be ≤ maximumIntegerDigits. If the new value for minimumIntegerDigits exceeds the current value of maximumIntegerDigits, then maximumIntegerDigits will also be set to the new value- Parameters:
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.- See Also:
getMinimumIntegerDigits()
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getMaximumFractionDigits
public int getMaximumFractionDigits()
Returns the maximum number of digits allowed in the fraction portion of a number.- Returns:
- the maximum number of digits.
- See Also:
setMaximumFractionDigits(int)
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setMaximumFractionDigits
public void setMaximumFractionDigits(int newValue)
Sets the maximum number of digits allowed in the fraction portion of a number. maximumFractionDigits must be ≥ minimumFractionDigits. If the new value for maximumFractionDigits is less than the current value of minimumFractionDigits, then minimumFractionDigits will also be set to the new value.- Parameters:
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.- See Also:
getMaximumFractionDigits()
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getMinimumFractionDigits
public int getMinimumFractionDigits()
Returns the minimum number of digits allowed in the fraction portion of a number.- Returns:
- the minimum number of digits
- See Also:
setMinimumFractionDigits(int)
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setMinimumFractionDigits
public void setMinimumFractionDigits(int newValue)
Sets the minimum number of digits allowed in the fraction portion of a number. minimumFractionDigits must be ≤ maximumFractionDigits. If the new value for minimumFractionDigits exceeds the current value of maximumFractionDigits, then maximumIntegerDigits will also be set to the new value- Parameters:
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.- See Also:
getMinimumFractionDigits()
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getCurrency
public Currency getCurrency()
Gets the currency used by this number format when formatting currency values. The initial value is derived in a locale dependent way. The returned value may be null if no valid currency could be determined and no currency has been set usingsetCurrency.The default implementation throws
UnsupportedOperationException.- Returns:
- the currency used by this number format, or
null - Throws:
UnsupportedOperationException- if the number format class doesn't implement currency formatting- Since:
- 1.4
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setCurrency
public void setCurrency(Currency currency)
Sets the currency used by this number format when formatting currency values. This does not update the minimum or maximum number of fraction digits used by the number format.The default implementation throws
UnsupportedOperationException.- Parameters:
currency- the new currency to be used by this number format- Throws:
UnsupportedOperationException- if the number format class doesn't implement currency formattingNullPointerException- ifcurrencyis null- Since:
- 1.4
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getRoundingMode
public RoundingMode getRoundingMode()
Gets theRoundingModeused in this NumberFormat. The default implementation of this method in NumberFormat always throwsUnsupportedOperationException. Subclasses which handle different rounding modes should override this method.- Returns:
- The
RoundingModeused for this NumberFormat. - Throws:
UnsupportedOperationException- The default implementation always throws this exception- Since:
- 1.6
- See Also:
setRoundingMode(RoundingMode)
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setRoundingMode
public void setRoundingMode(RoundingMode roundingMode)
Sets theRoundingModeused in this NumberFormat. The default implementation of this method in NumberFormat always throwsUnsupportedOperationException. Subclasses which handle different rounding modes should override this method.- Parameters:
roundingMode- TheRoundingModeto be used- Throws:
UnsupportedOperationException- The default implementation always throws this exceptionNullPointerException- ifroundingModeis null- Since:
- 1.6
- See Also:
getRoundingMode()
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