com.ibm.icu.text

Class NumberFormat

Known Direct Subclasses:
DecimalFormat, RuleBasedNumberFormat

public abstract class NumberFormat
extends UFormat

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.

This is an enhanced version of NumberFormat that is based on the standard version in the JDK. New or changed functionality is labeled NEW or CHANGED.

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);
 
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.
 NumberFormat nf = NumberFormat.getInstance();
 for (int i = 0; i <32a.length; ++i) {
     output.println(nf.format(myNumber[i]) + "; ");
 }
 
To format a number for a different Locale, specify it in the call to getInstance.
 NumberFormat nf = NumberFormat.getInstance(Locale.FRENCH);
 
You can also use a NumberFormat to parse numbers:
 myNumber = nf.parse(myString);
 
Use 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. And 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. 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 is 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 '6') if false, "3456.78" -> 3456.78 (and leaves the parse position just after '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 on DecimalFormat.

You can also use forms of the parse and format methods with ParsePosition and FieldPosition to allow you to:

For example, you can align numbers in two ways:
  1. If you are using a monospaced font with spacing for alignment, you can pass the 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.
  2. 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.

DecimalFormat

DecimalFormat is the concrete implementation of NumberFormat, and the NumberFormat API is essentially an abstraction from DecimalFormat's API. Refer to DecimalFormat for more information about this API. see DecimalFormat see java.text.ChoiceFormat

Authors:
Mark Davis
Helena Shih
Alan Liu

Nested Class Summary

static class
NumberFormat.NumberFormatFactory
A NumberFormatFactory is used to register new number formats.
static class
NumberFormat.SimpleNumberFormatFactory
A NumberFormatFactory that supports a single locale.

Field Summary

static int
FRACTION_FIELD
Field constant used to construct a FieldPosition object.
static int
INTEGER_FIELD
Field constant used to construct a FieldPosition object.

Constructor Summary

NumberFormat()
Empty constructor.

Method Summary

Object
clone()
Overrides Cloneable.
boolean
equals(Object obj)
Overrides equals.
String
format(BigInteger number)
NEW Convenience method to format a BigInteger.
abstract StringBuffer
format(BigInteger number, StringBuffer toAppendTo, FieldPosition pos)
NEW Format a BigInteger.
StringBuffer
format(Object number, StringBuffer toAppendTo, FieldPosition pos)
CHANGED Format an object.
String
format(BigDecimal number)
NEW Convenience method to format an ICU BigDecimal.
abstract StringBuffer
format(BigDecimal number, StringBuffer toAppendTo, FieldPosition pos)
NEW Format a BigDecimal.
String
format(CurrencyAmount currAmt)
NEW Convenience method to format a CurrencyAmount.
StringBuffer
format(CurrencyAmount currAmt, StringBuffer toAppendTo, FieldPosition pos)
NEW Format a CurrencyAmount.
String
format(double number)
Specialization of format.
abstract StringBuffer
format(double number, StringBuffer toAppendTo, FieldPosition pos)
Specialization of format.
String
format(BigDecimal number)
NEW Convenience method to format a BigDecimal.
abstract StringBuffer
format(BigDecimal number, StringBuffer toAppendTo, FieldPosition pos)
NEW Format a BigDecimal.
String
format(long number)
Specialization of format.
abstract StringBuffer
format(long number, StringBuffer toAppendTo, FieldPosition pos)
Specialization of format.
static Locale[]
getAvailableLocales()
Get the list of Locales for which NumberFormats are available.
static ULocale[]
getAvailableULocales()
Get the list of Locales for which NumberFormats are available.
Currency
getCurrency()
Gets the Currency object used to display currency amounts.
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
getCurrencyInstance(ULocale inLocale)
Returns a currency format for the specified locale.
protected Currency
getEffectiveCurrency()
Returns the currency in effect for this formatter.
static NumberFormat
getInstance()
Returns the default number format for the current default locale.
static NumberFormat
getInstance(Locale inLocale)
Returns the default number format for the specified locale.
static NumberFormat
getInstance(ULocale inLocale)
Returns the default 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.
static NumberFormat
getIntegerInstance(ULocale 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
getNumberInstance(ULocale inLocale)
Returns a general-purpose number format for the specified locale.
protected static String
getPattern(Locale forLocale, int choice)
Deprecated. ICU 3.4 subclassers should override getPattern(ULocale, int) instead of this method.
protected static String
getPattern(ULocale forLocale, int choice)
Returns the pattern for the provided locale and choice.
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.
static NumberFormat
getPercentInstance(ULocale inLocale)
Returns a percentage format for the specified locale.
static NumberFormat
getScientificInstance()
NEW Returns a scientific format for the current default locale.
static NumberFormat
getScientificInstance(Locale inLocale)
NEW Returns a scientific format for the specified locale.
static NumberFormat
getScientificInstance(ULocale inLocale)
NEW Returns a scientific format for the specified locale.
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(String text)
Parses text from the beginning of the given string to produce a number.
abstract Number
parse(String text, 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 parsePosition)
static Object
registerFactory(NumberFormat.NumberFormatFactory factory)
Registers a new NumberFormatFactory.
void
setCurrency(Currency theCurrency)
Sets the Currency object used to display currency amounts.
void
setGroupingUsed(boolean newValue)
Sets 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.
static boolean
unregister(Object registryKey)
Unregister the factory or instance associated with this key (obtained from registerInstance or registerFactory).

Methods inherited from class com.ibm.icu.text.UFormat

getLocale

Field Details

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.
Field Value:
1

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.
Field Value:
0

Constructor Details

NumberFormat

public NumberFormat()
Empty constructor. Public for compatibily with JDK which lets the compiler generate a default public constructor even though this is an abstract class.

Method Details

clone

public Object clone()
Overrides Cloneable.

equals

public boolean equals(Object obj)
Overrides equals. Two NumberFormats are equal if they are of the same class and the settings (groupingUsed, parseIntegerOnly, maximumIntegerDigits, etc. are equal.
Parameters:
obj - the object to compare against
Returns:
true if the object is equal to this.

format

public final String format(BigInteger number)
NEW Convenience method to format a BigInteger.

format

public abstract StringBuffer format(BigInteger number,
                                    StringBuffer toAppendTo,
                                    FieldPosition pos)
NEW Format a BigInteger.

format

public StringBuffer format(Object number,
                           StringBuffer toAppendTo,
                           FieldPosition pos)
CHANGED Format an object. Change: recognizes BigInteger and BigDecimal objects.

format

public final String format(BigDecimal number)
NEW Convenience method to format an ICU BigDecimal.

format

public abstract StringBuffer format(BigDecimal number,
                                    StringBuffer toAppendTo,
                                    FieldPosition pos)
NEW Format a BigDecimal.

format

public final String format(CurrencyAmount currAmt)
NEW Convenience method to format a CurrencyAmount.

format

public StringBuffer format(CurrencyAmount currAmt,
                           StringBuffer toAppendTo,
                           FieldPosition pos)
NEW Format a CurrencyAmount.

format

public final String format(double number)
Specialization of format.

format

public abstract StringBuffer format(double number,
                                    StringBuffer toAppendTo,
                                    FieldPosition pos)
Specialization of format.

format

public final String format(BigDecimal number)
NEW Convenience method to format a BigDecimal.

format

public abstract StringBuffer format(BigDecimal number,
                                    StringBuffer toAppendTo,
                                    FieldPosition pos)
NEW Format a BigDecimal.

format

public final String format(long number)
Specialization of format.

format

public abstract StringBuffer format(long number,
                                    StringBuffer toAppendTo,
                                    FieldPosition pos)
Specialization of format.

getAvailableLocales

public static Locale[] getAvailableLocales()
Get the list of Locales for which NumberFormats are available.
Returns:
the available locales

getAvailableULocales

public static ULocale[] getAvailableULocales()
Get the list of Locales for which NumberFormats are available.
Returns:
the available locales

getCurrency

public Currency getCurrency()
Gets the Currency object used to display currency amounts. This may be null.

getCurrencyInstance

public static final NumberFormat getCurrencyInstance()
Returns a currency format for the current default locale.
Returns:
a number format for currency

getCurrencyInstance

public static NumberFormat getCurrencyInstance(Locale inLocale)
Returns a currency format for the specified locale.
Returns:
a number format for currency

getCurrencyInstance

public static NumberFormat getCurrencyInstance(ULocale inLocale)
Returns a currency format for the specified locale.
Returns:
a number format for currency

getEffectiveCurrency

protected Currency getEffectiveCurrency()
Returns the currency in effect for this formatter. Subclasses should override this method as needed. Unlike getCurrency(), this method should never return null.
Returns:
a non-null Currency

getInstance

public static final NumberFormat getInstance()
Returns the default number format for the current default locale. The default format is one of the styles provided by the other factory methods: getNumberInstance, getIntegerInstance, getCurrencyInstance or getPercentInstance. Exactly which one is locale-dependent.

getInstance

public static NumberFormat getInstance(Locale inLocale)
Returns the default number format for the specified locale. The default format is one of the styles provided by the other factory methods: getNumberInstance, getCurrencyInstance or getPercentInstance. Exactly which one is locale-dependent.

getInstance

public static NumberFormat getInstance(ULocale inLocale)
Returns the default number format for the specified locale. The default format is one of the styles provided by the other factory methods: getNumberInstance, getCurrencyInstance or getPercentInstance. Exactly which one is locale-dependent.

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 IEEE half-even rounding (see ROUND_HALF_EVEN) for formatting, and to parse only the integer part of an input string (see isParseIntegerOnly).
Returns:
a number format for integer values

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 IEEE half-even rounding (see ROUND_HALF_EVEN) for formatting, and to parse only the integer part of an input string (see isParseIntegerOnly).
Parameters:
inLocale - the locale for which a number format is needed
Returns:
a number format for integer values

getIntegerInstance

public static NumberFormat getIntegerInstance(ULocale 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 IEEE half-even rounding (see ROUND_HALF_EVEN) for formatting, and to parse only the integer part of an input string (see isParseIntegerOnly).
Parameters:
inLocale - the locale for which a number format is needed
Returns:
a number format for integer values

getMaximumFractionDigits

public int getMaximumFractionDigits()
Returns the maximum number of digits allowed in the fraction portion of a number. The default value is 3, which subclasses can override. When formatting, the exact behavior when this value is exceeded is subclass-specific. When parsing, this has no effect.
Returns:
the maximum number of fraction digits

getMaximumIntegerDigits

public int getMaximumIntegerDigits()
Returns the maximum number of digits allowed in the integer portion of a number. The default value is 40, which subclasses can override. When formatting, the exact behavior when this value is exceeded is subclass-specific. When parsing, this has no effect.
Returns:
the maximum number of integer digits

getMinimumFractionDigits

public int getMinimumFractionDigits()
Returns the minimum number of digits allowed in the fraction portion of a number. The default value is 0, which subclasses can override. When formatting, if this value is not reached, numbers are padded on the right with the locale-specific '0' character to ensure at least this number of fraction digits. When parsing, this has no effect.
Returns:
the minimum number of fraction digits

getMinimumIntegerDigits

public int getMinimumIntegerDigits()
Returns the minimum number of digits allowed in the integer portion of a number. The default value is 1, which subclasses can override. When formatting, if this value is not reached, numbers are padded on the left with the locale-specific '0' character to ensure at least this number of integer digits. When parsing, this has no effect.
Returns:
the minimum number of integer digits

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.

getNumberInstance

public static NumberFormat getNumberInstance(ULocale inLocale)
Returns a general-purpose number format for the specified locale.

getPattern

protected static String getPattern(Locale forLocale,
                                   int choice)

Deprecated. ICU 3.4 subclassers should override getPattern(ULocale, int) instead of this method.

Returns the pattern for the provided locale and choice.
Parameters:
forLocale - the locale of the data.
choice - the pattern format.
Returns:
the pattern

getPattern

protected static String getPattern(ULocale forLocale,
                                   int choice)
Returns the pattern for the provided locale and choice.
Parameters:
forLocale - the locale of the data.
choice - the pattern format.
Returns:
the pattern

getPercentInstance

public static final NumberFormat getPercentInstance()
Returns a percentage format for the current default locale.
Returns:
a number format for percents

getPercentInstance

public static NumberFormat getPercentInstance(Locale inLocale)
Returns a percentage format for the specified locale.
Returns:
a number format for percents

getPercentInstance

public static NumberFormat getPercentInstance(ULocale inLocale)
Returns a percentage format for the specified locale.
Returns:
a number format for percents

getScientificInstance

public static final NumberFormat getScientificInstance()
NEW Returns a scientific format for the current default locale.
Returns:
a scientific number format

getScientificInstance

public static NumberFormat getScientificInstance(Locale inLocale)
NEW Returns a scientific format for the specified locale.
Returns:
a scientific number format

getScientificInstance

public static NumberFormat getScientificInstance(ULocale inLocale)
NEW Returns a scientific format for the specified locale.
Returns:
a scientific number format

hashCode

public int hashCode()
Overrides hashCode

isGroupingUsed

public boolean isGroupingUsed()
Returns true if grouping is used in this format. For example, in the en_US locale, with grouping on, the number 1234567 will be formatted as "1,234,567". The grouping separator as well as the size of each group is locale-dependent and is determined by subclasses of NumberFormat. Grouping affects both parsing and formatting.
Returns:
true if grouping is used

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. The decimal separator accepted by the parse operation is locale-dependent and determined by the subclass.
Returns:
true if this will parse integers only

parse

public Number parse(String text)
            throws ParseException
Parses text from the beginning of the given string to produce a number. The method might not use the entire text of the given string.
Parameters:
text - A String whose beginning should be parsed.
Returns:
A Number parsed from the string.
See Also:
format

parse

public abstract Number parse(String text,
                             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!

parseObject

public final Object parseObject(String source,
                                ParsePosition parsePosition)

registerFactory

public static Object registerFactory(NumberFormat.NumberFormatFactory factory)
Registers a new NumberFormatFactory. The factory is adopted by the service and must not be modified. The returned object is a key that can be used to unregister this factory.
Parameters:
factory - the factory to register
Returns:
a key with which to unregister the factory

setCurrency

public void setCurrency(Currency theCurrency)
Sets the Currency object used to display currency amounts. This takes effect immediately, if this format is a currency format. If this format is not a currency format, then the currency object is used if and when this object becomes a currency format.
Parameters:
theCurrency - new currency object to use. May be null for some subclasses.

setGroupingUsed

public void setGroupingUsed(boolean newValue)
Sets whether or not grouping will be used in this format. Grouping affects both parsing and formatting.
Parameters:
newValue - true to use grouping.

setMaximumFractionDigits

public void setMaximumFractionDigits(int newValue)
Sets the maximum number of digits allowed in the fraction portion of a number. This 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.

setMaximumIntegerDigits

public void setMaximumIntegerDigits(int newValue)
Sets the maximum number of digits allowed in the integer portion of a number. This 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. Subclasses might enforce an upper limit to this value appropriate to the numeric type being formatted.

setMinimumFractionDigits

public void setMinimumFractionDigits(int newValue)
Sets the minimum number of digits allowed in the fraction portion of a number. This must be <= maximumFractionDigits. If the new value for minimumFractionDigits exceeds the current value of maximumFractionDigits, then maximumFractionDigits 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. Subclasses might enforce an upper limit to this value appropriate to the numeric type being formatted.

setMinimumIntegerDigits

public void setMinimumIntegerDigits(int newValue)
Sets the minimum number of digits allowed in the integer portion of a number. This must be <= maximumIntegerDigits. If the new value for minimumIntegerDigits is more than 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. Subclasses might enforce an upper limit to this value appropriate to the numeric type being formatted.

setParseIntegerOnly

public void setParseIntegerOnly(boolean value)
Sets whether or not numbers should be parsed as integers only.
Parameters:
value - true if this should parse integers only

unregister

public static boolean unregister(Object registryKey)
Unregister the factory or instance associated with this key (obtained from registerInstance or registerFactory).
Parameters:
registryKey - a key obtained from registerFactory
Returns:
true if the object was successfully unregistered

Copyright (c) 2006 IBM Corporation and others.