- java.lang.Object
-
- java.text.Format
-
- java.text.NumberFormat
-
- All Implemented Interfaces:
- Serializable, Cloneable
- Direct Known Subclasses:
- ChoiceFormat, 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:
myString = NumberFormat.getInstance().format(myNumber);
NumberFormat nf = NumberFormat.getInstance(); for (int i = 0; i < myNumber.length; ++i) { output.println(nf.format(myNumber[i]) + "; "); }
getInstance
.NumberFormat nf = NumberFormat.getInstance(Locale.FRENCH);
NumberFormat
to parse numbers:myNumber = nf.parse(myString);
getInstance
orgetNumberInstance
to get the normal number format. UsegetIntegerInstance
to get an integer number format. UsegetCurrencyInstance
to get the currency number format. And usegetPercentInstance
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 theNumberFormat
you get from the factory methods to aDecimalFormat
. This will work for the vast majority of locales; just remember to put it in atry
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
andformat
methods withParsePosition
andFieldPosition
to 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
FieldPosition
in your format call, withfield
=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. - 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.
- See Also:
DecimalFormat
,ChoiceFormat
, Serialized Form
-
-
Nested Class Summary
Nested Classes Modifier and Type Class and Description static class
NumberFormat.Field
Defines constants that are used as attribute keys in theAttributedCharacterIterator
returned fromNumberFormat.formatToCharacterIterator
and as field identifiers inFieldPosition
.
-
Field Summary
Fields Modifier and Type Field and Description static int
FRACTION_FIELD
Field constant used to construct a FieldPosition object.static int
INTEGER_FIELD
Field constant used to construct a FieldPosition object.
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Constructor Summary
Constructors Modifier Constructor and Description protected
NumberFormat()
Sole constructor.
-
Method Summary
Methods Modifier and Type Method and Description Object
clone()
Overrides Cloneableboolean
equals(Object obj)
Overrides equalsString
format(double number)
Specialization of format.abstract StringBuffer
format(double number, StringBuffer toAppendTo, FieldPosition pos)
Specialization of format.String
format(long number)
Specialization of format.abstract StringBuffer
format(long number, StringBuffer toAppendTo, FieldPosition pos)
Specialization of format.StringBuffer
format(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*Instance
methods of this class can return localized instances.Currency
getCurrency()
Gets the currency used by this number format when formatting currency values.static NumberFormat
getCurrencyInstance()
Returns a currency format for the current default locale.static NumberFormat
getCurrencyInstance(Locale inLocale)
Returns a currency format for the specified locale.static NumberFormat
getInstance()
Returns a general-purpose number format for the current default locale.static NumberFormat
getInstance(Locale inLocale)
Returns a general-purpose number format for the specified locale.static NumberFormat
getIntegerInstance()
Returns an integer number format for the current default locale.static NumberFormat
getIntegerInstance(Locale inLocale)
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 NumberFormat
getNumberInstance()
Returns a general-purpose number format for the current default locale.static NumberFormat
getNumberInstance(Locale inLocale)
Returns a general-purpose number format for the specified locale.static NumberFormat
getPercentInstance()
Returns a percentage format for the current default locale.static NumberFormat
getPercentInstance(Locale inLocale)
Returns a percentage format for the specified locale.RoundingMode
getRoundingMode()
Gets theRoundingMode
used in this NumberFormat.int
hashCode()
Overrides hashCodeboolean
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(String source)
Parses text from the beginning of the given string to produce a number.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.Object
parseObject(String source, ParsePosition pos)
Parses text from a string to produce aNumber
.void
setCurrency(Currency currency)
Sets the currency used by this number format when formatting currency values.void
setGroupingUsed(boolean newValue)
Set whether or not grouping will be used in this format.void
setMaximumFractionDigits(int newValue)
Sets the maximum number of digits allowed in the fraction portion of a number.void
setMaximumIntegerDigits(int newValue)
Sets the maximum number of digits allowed in the integer portion of a number.void
setMinimumFractionDigits(int newValue)
Sets the minimum number of digits allowed in the fraction portion of a number.void
setMinimumIntegerDigits(int newValue)
Sets the minimum number of digits allowed in the integer portion of a number.void
setParseIntegerOnly(boolean value)
Sets whether or not numbers should be parsed as integers only.void
setRoundingMode(RoundingMode roundingMode)
Sets theRoundingMode
used in this NumberFormat.-
Methods inherited from class java.text.Format
format, formatToCharacterIterator, parseObject
-
-
-
-
Field Detail
-
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
-
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
-
-
Constructor Detail
-
NumberFormat
protected NumberFormat()
Sole constructor. (For invocation by subclass constructors, typically implicit.)
-
-
Method Detail
-
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 tolong
without loss of information, includingBigInteger
values with abit length
of 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 forBigInteger
andBigDecimal
values.- Specified by:
format
in classFormat
- Parameters:
number
- the number to formattoAppendTo
- theStringBuffer
to which the formatted text is to be appendedpos
- On input: an alignment field, if desired. On output: the offsets of the alignment field.- Returns:
- the value passed in as
toAppendTo
- Throws:
IllegalArgumentException
- ifnumber
is null or not an instance ofNumber
.NullPointerException
- iftoAppendTo
orpos
is nullArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
FieldPosition
-
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 ofpos
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 updatedpos
can be used to indicate the starting point for the next call to this method. If an error occurs, then the index ofpos
is not changed, the error index ofpos
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.- Specified by:
parseObject
in classFormat
- Parameters:
source
- AString
, part of which should be parsed.pos
- AParsePosition
object with index and error index information as described above.- Returns:
- A
Number
parsed from the string. In case of error, returns null. - Throws:
NullPointerException
- ifpos
is null.
-
format
public final String format(double number)
Specialization of format.- Throws:
ArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
Format.format(java.lang.Object)
-
format
public final String format(long number)
Specialization of format.- Throws:
ArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
Format.format(java.lang.Object)
-
format
public abstract StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition pos)
Specialization of format.- Throws:
ArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
Format.format(java.lang.Object)
-
format
public abstract StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition pos)
Specialization of format.- Throws:
ArithmeticException
- if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY- See Also:
Format.format(java.lang.Object)
-
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!
-
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
- AString
whose beginning should be parsed.- Returns:
- A
Number
parsed from the string. - Throws:
ParseException
- if the beginning of the specified string cannot be parsed.
-
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 dependant and determined by sub-classes of NumberFormat.
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setParseIntegerOnly
public void setParseIntegerOnly(boolean value)
Sets whether or not numbers should be parsed as integers only.- See Also:
isParseIntegerOnly()
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getInstance
public static final NumberFormat getInstance()
Returns a general-purpose number format for the current default locale. This is the same as callinggetNumberInstance()
.
-
getInstance
public static NumberFormat getInstance(Locale inLocale)
Returns a general-purpose number format for the specified locale. This is the same as callinggetNumberInstance(inLocale)
.
-
getNumberInstance
public static final NumberFormat getNumberInstance()
Returns a general-purpose number format for the current default locale.
-
getNumberInstance
public static NumberFormat getNumberInstance(Locale inLocale)
Returns a general-purpose number format for the specified locale.
-
getIntegerInstance
public static final NumberFormat getIntegerInstance()
Returns an integer number format for the current default 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
).- Returns:
- a number format for integer values
- Since:
- 1.4
- See Also:
getRoundingMode()
-
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
).- Returns:
- a number format for integer values
- Since:
- 1.4
- See Also:
getRoundingMode()
-
getCurrencyInstance
public static final NumberFormat getCurrencyInstance()
Returns a currency format for the current default locale.
-
getCurrencyInstance
public static NumberFormat getCurrencyInstance(Locale inLocale)
Returns a currency format for the specified locale.
-
getPercentInstance
public static final NumberFormat getPercentInstance()
Returns a percentage format for the current default locale.
-
getPercentInstance
public static NumberFormat getPercentInstance(Locale inLocale)
Returns a percentage format for the specified locale.
-
getAvailableLocales
public static Locale[] getAvailableLocales()
Returns an array of all locales for which theget*Instance
methods of this class can return localized instances. The returned array represents the union of locales supported by the Java runtime and by installedNumberFormatProvider
implementations. It must contain at least aLocale
instance equal toLocale.US
.- Returns:
- An array of locales for which localized
NumberFormat
instances are available.
-
hashCode
public int hashCode()
Overrides hashCode- Overrides:
hashCode
in classObject
- Returns:
- a hash code value for this object.
- See Also:
Object.equals(java.lang.Object)
,System.identityHashCode(java.lang.Object)
-
equals
public boolean equals(Object obj)
Overrides equals- Overrides:
equals
in classObject
- Parameters:
obj
- the reference object with which to compare.- Returns:
true
if this object is the same as the obj argument;false
otherwise.- See Also:
Object.hashCode()
,HashMap
-
clone
public Object clone()
Overrides Cloneable
-
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 dependant and is determined by sub-classes of NumberFormat.- See Also:
setGroupingUsed(boolean)
-
setGroupingUsed
public void setGroupingUsed(boolean newValue)
Set whether or not grouping will be used in this format.- See Also:
isGroupingUsed()
-
getMaximumIntegerDigits
public int getMaximumIntegerDigits()
Returns the maximum number of digits allowed in the integer portion of a number.- 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()
-
getMinimumIntegerDigits
public int getMinimumIntegerDigits()
Returns the minimum number of digits allowed in the integer portion of a number.- See Also:
setMinimumIntegerDigits(int)
-
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()
-
getMaximumFractionDigits
public int getMaximumFractionDigits()
Returns the maximum number of digits allowed in the fraction portion of a number.- See Also:
setMaximumFractionDigits(int)
-
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()
-
getMinimumFractionDigits
public int getMinimumFractionDigits()
Returns the minimum number of digits allowed in the fraction portion of a number.- See Also:
setMinimumFractionDigits(int)
-
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()
-
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
-
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
- ifcurrency
is null- Since:
- 1.4
-
getRoundingMode
public RoundingMode getRoundingMode()
Gets theRoundingMode
used 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
RoundingMode
used for this NumberFormat. - Throws:
UnsupportedOperationException
- The default implementation always throws this exception- Since:
- 1.6
- See Also:
setRoundingMode(RoundingMode)
-
setRoundingMode
public void setRoundingMode(RoundingMode roundingMode)
Sets theRoundingMode
used 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
- TheRoundingMode
to be used- Throws:
UnsupportedOperationException
- The default implementation always throws this exceptionNullPointerException
- ifroundingMode
is null- Since:
- 1.6
- See Also:
getRoundingMode()
-
-
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Dokument erstellt 11/06/2005, zuletzt geändert 04/03/2020
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