Package com.ibm.icu.text

Class NumberFormat

  • All Implemented Interfaces:
    Serializable, Cloneable
    Direct Known Subclasses:
    DateNumberFormat, 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. 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 < a.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. Some factory methods are found within subclasses of NumberFormat. With this format, a fraction like 0.53 is displayed as 53%.

    Starting from ICU 4.2, you can use getInstance() by passing in a 'style' as parameter to get the correct instance. For example, use getInstance(...NUMBERSTYLE) to get the normal number format, getInstance(...PERCENTSTYLE) to get a format for displaying percentage, getInstance(...SCIENTIFICSTYLE) to get a format for displaying scientific number, getInstance(...INTEGERSTYLE) to get an integer number format, getInstance(...CURRENCYSTYLE) to get the currency number format, in which the currency is represented by its symbol, for example, "$3.00". getInstance(...ISOCURRENCYSTYLE) to get the currency number format, in which the currency is represented by its ISO code, for example "USD3.00". getInstance(...PLURALCURRENCYSTYLE) to get the currency number format, in which the currency is represented by its full name in plural format, for example, "3.00 US dollars" or "1.00 US dollar".

    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:

    • progressively parse through pieces of a string
    • align the decimal point and other areas
    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
    See Also:
    Serialized Form

    • Field Detail

      • NUMBERSTYLE

        public static final int NUMBERSTYLE
        Constant to specify normal number style of format.
        See Also:
        Constant Field Values

      • CURRENCYSTYLE

        public static final int CURRENCYSTYLE
        Constant to specify general currency style of format. Defaults to STANDARDCURRENCYSTYLE, using currency symbol, for example "$3.00", with non-accounting style for negative values (e.g. minus sign). The specific style may be specified using the -cf- locale key.
        See Also:
        Constant Field Values

      • PERCENTSTYLE

        public static final int PERCENTSTYLE
        Constant to specify a style of format to display percent.
        See Also:
        Constant Field Values

      • SCIENTIFICSTYLE

        public static final int SCIENTIFICSTYLE
        Constant to specify a style of format to display scientific number.
        See Also:
        Constant Field Values

      • INTEGERSTYLE

        public static final int INTEGERSTYLE
        Constant to specify a integer number style format.
        See Also:
        Constant Field Values

      • ISOCURRENCYSTYLE

        public static final int ISOCURRENCYSTYLE
        Constant to specify currency style of format which uses currency ISO code to represent currency, for example: "USD3.00".
        See Also:
        Constant Field Values

      • PLURALCURRENCYSTYLE

        public static final int PLURALCURRENCYSTYLE
        Constant to specify currency style of format which uses currency long name with plural format to represent currency, for example, "3.00 US Dollars".
        See Also:
        Constant Field Values

      • ACCOUNTINGCURRENCYSTYLE

        public static final int ACCOUNTINGCURRENCYSTYLE
        Constant to specify currency style of format which uses currency symbol to represent currency for accounting, for example: "($3.00), instead of "-$3.00" (CURRENCYSTYLE). Overrides any style specified using -cf- key in locale.
        See Also:
        Constant Field Values

      • CASHCURRENCYSTYLE

        public static final int CASHCURRENCYSTYLE
        Constant to specify currency cash style of format which uses currency ISO code to represent currency, for example: "NT$3" instead of "NT$3.23".
        See Also:
        Constant Field Values

      • STANDARDCURRENCYSTYLE

        public static final int STANDARDCURRENCYSTYLE
        Constant to specify currency style of format which uses currency symbol to represent currency, for example "$3.00", using non-accounting style for negative values (e.g. minus sign). Overrides any style specified using -cf- key in locale.
        See Also:
        Constant Field Values

      • 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

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

    • 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. recognizes BigInteger and BigDecimal objects.
        Specified by:
        format in class Format
        Parameters:
        number - the object to format.
        toAppendTo - the string buffer where the formatted string is appended to.
        pos - on input: an optional alignment field; on output: the offsets of the alignment field in the formatted text.
        Returns:
        the string buffer.
        See Also:
        Format.format(Object, StringBuffer, FieldPosition)

      • format

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

      • format

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

      • format

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

      • format

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

      • 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!
        See Also:
        isParseIntegerOnly(), Format.parseObject(String, ParsePosition)

      • parseCurrency

        public CurrencyAmount parseCurrency​(CharSequence text,
                                    ParsePosition pos)
        Parses text from the given string as a CurrencyAmount. Unlike the parse() method, this method will attempt to parse a generic currency name, searching for a match of this object's locale's currency display names, or for a 3-letter ISO currency code. This method will fail if this format is not a currency format, that is, if it does not contain the currency pattern symbol (U+00A4) in its prefix or suffix.
        Parameters:
        text - the text to parse
        pos - input-output position; on input, the position within text to match; must have 0 <= pos.getIndex() < text.length(); on output, the position after the last matched character. If the parse fails, the position in unchanged upon output.
        Returns:
        a CurrencyAmount, or null upon failure

      • 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

      • 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
        See Also:
        isParseIntegerOnly()

      • setParseStrict

        public void setParseStrict​(boolean value)
        Sets whether strict parsing is in effect. When this is true, the following conditions cause a parse failure (examples use the pattern "#,##0.#"):
        • Leading or doubled grouping separators
          ',123' and '1,,234" fail
        • Groups of incorrect length when grouping is used
          '1,23' and '1234,567' fail, but '1234' passes
        • Grouping separators used in numbers followed by exponents
          '1,234E5' fails, but '1234E5' and '1,234E' pass ('E' is not an exponent when not followed by a number)
        When strict parsing is off, all grouping separators are ignored. This is the default behavior.
        Parameters:
        value - True to enable strict parsing. Default is false.
        See Also:
        isParseStrict()

      • isParseStrict

        public boolean isParseStrict()
        Returns whether strict parsing is in effect.
        Returns:
        true if strict parsing is in effect
        See Also:
        setParseStrict(boolean)

      • setContext

        public void setContext​(DisplayContext context)
        Set a particular DisplayContext value in the formatter, such as CAPITALIZATION_FOR_STANDALONE.
        Parameters:
        context - The DisplayContext value to set.

      • getContext

        public DisplayContext getContext​(DisplayContext.Type type)
        Get the formatter's DisplayContext value for the specified DisplayContext.Type, such as CAPITALIZATION.
        Parameters:
        type - the DisplayContext.Type whose value to return
        Returns:
        the current DisplayContext setting for the specified type

      • getInstance

        public static final NumberFormat getInstance()
        Returns the default number format for the current default FORMAT 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.
        See Also:
        ULocale.Category.FORMAT

      • 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.

      • getInstance

        public static final NumberFormat getInstance​(int style)
        Returns a specific style number format for default FORMAT locale.
        Parameters:
        style - number format style
        See Also:
        ULocale.Category.FORMAT

      • getInstance

        public static NumberFormat getInstance​(Locale inLocale,
                                       int style)
        Returns a specific style number format for a specific locale.
        Parameters:
        inLocale - the specific locale.
        style - number format style

      • getNumberInstance

        public static final NumberFormat getNumberInstance()
        Returns a general-purpose number format for the current default FORMAT locale.
        See Also:
        ULocale.Category.FORMAT

      • 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.

      • getIntegerInstance

        public static final NumberFormat getIntegerInstance()
        Returns an integer number format for the current default FORMAT 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
        See Also:
        ULocale.Category.FORMAT

      • 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

      • getCurrencyInstance

        public static final NumberFormat getCurrencyInstance()
        Returns a currency format for the current default FORMAT locale.
        Returns:
        a number format for currency
        See Also:
        ULocale.Category.FORMAT

      • 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

      • getPercentInstance

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

      • 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()
        Returns a scientific format for the current default FORMAT locale.
        Returns:
        a scientific number format
        See Also:
        ULocale.Category.FORMAT

      • getScientificInstance

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

      • getScientificInstance

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

      • getAvailableLocales

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

      • getAvailableULocales

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

      • 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.

        Because ICU may choose to cache NumberFormat objects internally, this must be called at application startup, prior to any calls to NumberFormat.getInstance to avoid undefined behavior.

        Parameters:
        factory - the factory to register
        Returns:
        a key with which to unregister the factory

      • unregister

        public static boolean unregister​(Object registryKey)
        Unregisters 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

      • 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.
        Overrides:
        equals in class Object
        Parameters:
        obj - the object to compare against
        Returns:
        true if the object is equal to this.
        See Also:
        Object.hashCode()

      • clone

        public Object clone()
        Overrides clone.
        Overrides:
        clone in class Format
        Returns:
        a shallow copy of this format.
        See Also:
        Cloneable

      • 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
        See Also:
        setGroupingUsed(boolean)

      • 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.
        See Also:
        isGroupingUsed()

      • 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
        See Also:
        setMaximumIntegerDigits(int)

      • 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.
        See Also:
        getMaximumIntegerDigits()

      • 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
        See Also:
        setMinimumIntegerDigits(int)

      • 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.
        See Also:
        getMinimumIntegerDigits()

      • 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
        See Also:
        setMaximumFractionDigits(int)

      • 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.
        See Also:
        getMaximumFractionDigits()

      • 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
        See Also:
        setMinimumFractionDigits(int)

      • 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.
        See Also:
        getMinimumFractionDigits()

      • 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.

      • getCurrency

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

      • getEffectiveCurrency

        @Deprecated
protected Currency getEffectiveCurrency()
        Deprecated.
        This API is ICU internal only.
        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

      • getRoundingMode

        public int getRoundingMode()
        Returns the rounding mode used in this NumberFormat. The default implementation of tis method in NumberFormat always throws UnsupportedOperationException.
        Returns:
        A rounding mode, between BigDecimal.ROUND_UP and BigDecimal.ROUND_UNNECESSARY.
        See Also:
        setRoundingMode(int)

      • setRoundingMode

        public void setRoundingMode​(int roundingMode)
        Set the rounding mode used in this NumberFormat. The default implementation of tis method in NumberFormat always throws UnsupportedOperationException.
        Parameters:
        roundingMode - A rounding mode, between BigDecimal.ROUND_UP and BigDecimal.ROUND_UNNECESSARY.
        See Also:
        getRoundingMode()

      • getInstance

        public static NumberFormat getInstance​(ULocale desiredLocale,
                                       int choice)
        Returns a specific style number format for a specific locale.
        Parameters:
        desiredLocale - the specific locale.
        choice - number format style
        Throws:
        IllegalArgumentException - if choice is not one of NUMBERSTYLE, CURRENCYSTYLE, PERCENTSTYLE, SCIENTIFICSTYLE, INTEGERSTYLE, ISOCURRENCYSTYLE, PLURALCURRENCYSTYLE, ACCOUNTINGCURRENCYSTYLE. CASHCURRENCYSTYLE, STANDARDCURRENCYSTYLE.

      • getPattern

        @Deprecated
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