NumberFormatter.java
// © 2017 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
package com.ibm.icu.number;
import com.ibm.icu.impl.number.DecimalFormatProperties;
import com.ibm.icu.text.DecimalFormatSymbols;
import com.ibm.icu.util.ULocale;
import java.util.Locale;
/**
* All-in-one formatter for localized numbers, currencies, and units.
*
* <p>For a full list of options, see {@link NumberFormatterSettings}.
*
* <pre>
* // Most basic usage:
* NumberFormatter.withLocale(...).format(123).toString(); // 1,234 in en-US
*
* // Custom notation, unit, and rounding strategy:
* NumberFormatter.with()
* .notation(Notation.compactShort())
* .unit(Currency.getInstance("EUR"))
* .precision(Precision.maxDigits(2))
* .locale(...)
* .format(1234)
* .toString(); // €1.2K in en-US
*
* // Create a formatter in a private static final field:
* private static final LocalizedNumberFormatter formatter = NumberFormatter.withLocale(...)
* .unit(NoUnit.PERCENT)
* .precision(Precision.fixedFraction(3));
* formatter.format(5.9831).toString(); // 5.983% in en-US
*
* // Create a "template" in a private static final field but without setting a locale until the call site:
* private static final UnlocalizedNumberFormatter template = NumberFormatter.with()
* .sign(SignDisplay.ALWAYS)
* .unitWidth(UnitWidth.FULL_NAME);
* template.locale(...).format(new Measure(1234, MeasureUnit.METER)).toString(); // +1,234 meters in en-US
* </pre>
*
* <p>This API offers more features than {@link com.ibm.icu.text.DecimalFormat} and is geared toward
* new users of ICU.
*
* <p>NumberFormatter instances (i.e., LocalizedNumberFormatter and UnlocalizedNumberFormatter) are
* immutable and thread safe. This means that invoking a configuration method has no effect on the
* receiving instance; you must store and use the new number formatter instance it returns instead.
*
* <pre>
* UnlocalizedNumberFormatter formatter = UnlocalizedNumberFormatter.with()
* .notation(Notation.scientific());
* formatter.precision(Precision.maxFraction(2)); // does nothing!
* formatter.locale(ULocale.ENGLISH).format(9.8765).toString(); // prints "9.8765E0", not "9.88E0"
* </pre>
*
* <p>This API is based on the <em>fluent</em> design pattern popularized by libraries such as
* Google's Guava. For extensive details on the design of this API, read <a
* href="https://goo.gl/szi5VB">the design doc</a>.
*
* <p>Note: To format monetary/currency values, specify the currency in the `.unit()` function.
*
* @author Shane Carr
* @stable ICU 60
*/
public final class NumberFormatter {
private static final UnlocalizedNumberFormatter BASE = new UnlocalizedNumberFormatter();
/**
* An enum declaring how to resolve conflicts between maximum fraction digits and maximum
* significant digits.
*
* <p>There are two modes, RELAXED and STRICT:
*
* <ul>
* <li>RELAXED: Relax one of the two constraints (fraction digits or significant digits) in
* order to round the number to a higher level of precision.
* <li>STRICT: Enforce both constraints, resulting in the number being rounded to a lower
* level of precision.
* </ul>
*
* <p>The default settings for compact notation rounding are Max-Fraction = 0 (round to the
* nearest integer), Max-Significant = 2 (round to 2 significant digits), and priority RELAXED
* (choose the constraint that results in more digits being displayed).
*
* <p>Conflicting <i>minimum</i> fraction and significant digits are always resolved in the
* direction that results in more trailing zeros.
*
* <p>Example 1: Consider the number 3.141, with various different settings:
*
* <ul>
* <li>Max-Fraction = 1: "3.1"
* <li>Max-Significant = 3: "3.14"
* </ul>
*
* <p>The rounding priority determines how to resolve the conflict when both Max-Fraction and
* Max-Significant are set. With RELAXED, the less-strict setting (the one that causes more
* digits to be displayed) will be used; Max-Significant wins. With STRICT, the more-strict
* setting (the one that causes fewer digits to be displayed) will be used; Max-Fraction wins.
*
* <p>Example 2: Consider the number 8317, with various different settings:
*
* <ul>
* <li>Max-Fraction = 1: "8317"
* <li>Max-Significant = 3: "8320"
* </ul>
*
* <p>Here, RELAXED favors Max-Fraction and STRICT favors Max-Significant. Note that this larger
* number caused the two modes to favor the opposite result.
*
* @stable ICU 69
*/
public static enum RoundingPriority {
/**
* Favor greater precision by relaxing one of the rounding constraints.
*
* @stable ICU 69
*/
RELAXED,
/**
* Favor adherence to all rounding constraints by producing lower precision.
*
* @stable ICU 69
*/
STRICT,
}
/**
* An enum declaring how to render units, including currencies. Example outputs when formatting
* 123 USD and 123 meters in <em>en-CA</em>:
*
* <ul>
* <li>NARROW: "$123.00" and "123 m"
* <li>SHORT: "US$ 123.00" and "123 m"
* <li>FULL_NAME: "123.00 US dollars" and "123 meters"
* <li>ISO_CODE: "USD 123.00" and undefined behavior
* <li>HIDDEN: "123.00" and "123"
* </ul>
*
* <p>This enum is similar to {@link com.ibm.icu.text.MeasureFormat.FormatWidth}.
*
* @stable ICU 60
* @see NumberFormatter
*/
public static enum UnitWidth {
/**
* Print an abbreviated version of the unit name. Similar to SHORT, but always use the
* shortest available abbreviation or symbol. This option can be used when the context hints
* at the identity of the unit. For more information on the difference between NARROW and
* SHORT, see SHORT.
*
* <p>In CLDR, this option corresponds to the "Narrow" format for measure units and the
* "¤¤¤¤¤" placeholder for currencies.
*
* @stable ICU 60
* @see NumberFormatter
*/
NARROW,
/**
* Print an abbreviated version of the unit name. Similar to NARROW, but use a slightly
* wider abbreviation or symbol when there may be ambiguity. This is the default behavior.
*
* <p>For example, in <em>es-US</em>, the SHORT form for Fahrenheit is "{0} °F", but the
* NARROW form is "{0}°", since Fahrenheit is the customary unit for temperature in that
* locale.
*
* <p>In CLDR, this option corresponds to the "Short" format for measure units and the "¤"
* placeholder for currencies.
*
* @stable ICU 60
* @see NumberFormatter
*/
SHORT,
/**
* Print the full name of the unit, without any abbreviations.
*
* <p>In CLDR, this option corresponds to the default format for measure units and the "¤¤¤"
* placeholder for currencies.
*
* @stable ICU 60
* @see NumberFormatter
*/
FULL_NAME,
/**
* Use the three-digit ISO XXX code in place of the symbol for displaying currencies.
*
* <p>Behavior of this option with non-currency units is not defined at this time.
*
* <p>In CLDR, this option corresponds to the "¤¤" placeholder for currencies.
*
* @stable ICU 60
* @see NumberFormatter
*/
ISO_CODE,
/**
* Use the formal variant of the currency symbol; for example, "NT$" for the New Taiwan
* dollar in zh-TW.
*
* <p>Behavior of this option with non-currency units is not defined at this time.
*
* @stable ICU 67
* @see NumberFormatter
*/
FORMAL,
/**
* Use the alternate variant of the currency symbol; for example, "TL" for the Turkish lira
* (TRY).
*
* <p>Behavior of this option with non-currency units is not defined at this time.
*
* @stable ICU 67
* @see NumberFormatter
*/
VARIANT,
/**
* Format the number according to the specified unit, but do not display the unit. For
* currencies, apply monetary symbols and formats as with SHORT, but omit the currency
* symbol. For measure units, the behavior is equivalent to not specifying the unit at all.
*
* @stable ICU 60
* @see NumberFormatter
*/
HIDDEN,
}
/**
* An enum declaring the strategy for when and how to display grouping separators (i.e., the
* separator, often a comma or period, after every 2-3 powers of ten). The choices are several
* pre-built strategies for different use cases that employ locale data whenever possible.
* Example outputs for 1234 and 1234567 in <em>en-IN</em>:
*
* <ul>
* <li>OFF: 1234 and 12345
* <li>MIN2: 1234 and 12,34,567
* <li>AUTO: 1,234 and 12,34,567
* <li>ON_ALIGNED: 1,234 and 12,34,567
* <li>THOUSANDS: 1,234 and 1,234,567
* </ul>
*
* <p>The default is AUTO, which displays grouping separators unless the locale data says that
* grouping is not customary. To force grouping for all numbers greater than 1000 consistently
* across locales, use ON_ALIGNED. On the other hand, to display grouping less frequently than
* the default, use MIN2 or OFF. See the docs of each option for details.
*
* <p>Note: This enum specifies the strategy for grouping sizes. To set which character to use
* as the grouping separator, use the "symbols" setter.
*
* @stable ICU 61
* @see NumberFormatter
*/
public static enum GroupingStrategy {
/**
* Do not display grouping separators in any locale.
*
* @stable ICU 61
* @see NumberFormatter
*/
OFF,
/**
* Display grouping using locale defaults, except do not show grouping on values smaller
* than 10000 (such that there is a <em>minimum of two digits</em> before the first
* separator).
*
* <p>Note that locales may restrict grouping separators to be displayed only on 1 million
* or greater (for example, ee and hu) or disable grouping altogether (for example, bg
* currency).
*
* <p>Locale data is used to determine whether to separate larger numbers into groups of 2
* (customary in South Asia) or groups of 3 (customary in Europe and the Americas).
*
* @stable ICU 61
* @see NumberFormatter
*/
MIN2,
/**
* Display grouping using the default strategy for all locales. This is the default
* behavior.
*
* <p>Note that locales may restrict grouping separators to be displayed only on 1 million
* or greater (for example, ee and hu) or disable grouping altogether (for example, bg
* currency).
*
* <p>Locale data is used to determine whether to separate larger numbers into groups of 2
* (customary in South Asia) or groups of 3 (customary in Europe and the Americas).
*
* @stable ICU 61
* @see NumberFormatter
*/
AUTO,
/**
* Always display the grouping separator on values of at least 1000.
*
* <p>This option ignores the locale data that restricts or disables grouping, described in
* MIN2 and AUTO. This option may be useful to normalize the alignment of numbers, such as
* in a spreadsheet.
*
* <p>Locale data is used to determine whether to separate larger numbers into groups of 2
* (customary in South Asia) or groups of 3 (customary in Europe and the Americas).
*
* @stable ICU 61
* @see NumberFormatter
*/
ON_ALIGNED,
/**
* Use the Western defaults: groups of 3 and enabled for all numbers 1000 or greater. Do not
* use locale data for determining the grouping strategy.
*
* @stable ICU 61
* @see NumberFormatter
*/
THOUSANDS
}
/**
* An enum declaring how to denote positive and negative numbers. Example outputs when
* formatting 123, 0, and -123 in <em>en-US</em>:
*
* <ul>
* <li>AUTO: "123", "0", and "-123"
* <li>ALWAYS: "+123", "+0", and "-123"
* <li>NEVER: "123", "0", and "123"
* <li>ACCOUNTING: "$123", "$0", and "($123)"
* <li>ACCOUNTING_ALWAYS: "+$123", "+$0", and "($123)"
* <li>EXCEPT_ZERO: "+123", "0", and "-123"
* <li>ACCOUNTING_EXCEPT_ZERO: "+$123", "$0", and "($123)"
* </ul>
*
* <p>The exact format, including the position and the code point of the sign, differ by locale.
*
* @stable ICU 60
* @see NumberFormatter
*/
public static enum SignDisplay {
/**
* Show the minus sign on negative numbers, and do not show the sign on positive numbers.
* This is the default behavior.
*
* <p>If using this option, a sign will be displayed on negative zero, including negative
* numbers that round to zero. To hide the sign on negative zero, use the NEGATIVE option.
*
* @stable ICU 60
* @see NumberFormatter
*/
AUTO,
/**
* Show the minus sign on negative numbers and the plus sign on positive numbers, including
* zero. To hide the sign on zero, see {@link #EXCEPT_ZERO}.
*
* @stable ICU 60
* @see NumberFormatter
*/
ALWAYS,
/**
* Do not show the sign on positive or negative numbers.
*
* @stable ICU 60
* @see NumberFormatter
*/
NEVER,
/**
* Use the locale-dependent accounting format on negative numbers, and do not show the sign
* on positive numbers.
*
* <p>The accounting format is defined in CLDR and varies by locale; in many Western
* locales, the format is a pair of parentheses around the number.
*
* <p>Note: Since CLDR defines the accounting format in the monetary context only, this
* option falls back to the AUTO sign display strategy when formatting without a currency
* unit. This limitation may be lifted in the future.
*
* @stable ICU 60
* @see NumberFormatter
*/
ACCOUNTING,
/**
* Use the locale-dependent accounting format on negative numbers, and show the plus sign on
* positive numbers, including zero. For more information on the accounting format, see the
* ACCOUNTING sign display strategy. To hide the sign on zero, see {@link
* #ACCOUNTING_EXCEPT_ZERO}.
*
* @stable ICU 60
* @see NumberFormatter
*/
ACCOUNTING_ALWAYS,
/**
* Show the minus sign on negative numbers and the plus sign on positive numbers. Do not
* show a sign on zero, numbers that round to zero, or NaN.
*
* @stable ICU 61
* @see NumberFormatter
*/
EXCEPT_ZERO,
/**
* Use the locale-dependent accounting format on negative numbers, and show the plus sign on
* positive numbers. Do not show a sign on zero, numbers that round to zero, or NaN. For
* more information on the accounting format, see the ACCOUNTING sign display strategy.
*
* @stable ICU 61
* @see NumberFormatter
*/
ACCOUNTING_EXCEPT_ZERO,
/**
* Same as AUTO, but do not show the sign on negative zero.
*
* @stable ICU 69
*/
NEGATIVE,
/**
* Same as ACCOUNTING, but do not show the sign on negative zero.
*
* @stable ICU 69
*/
ACCOUNTING_NEGATIVE,
}
/**
* An enum declaring how to render the decimal separator. Example outputs when formatting 1 and
* 1.1 in <em>en-US</em>:
*
* <ul>
* <li>AUTO: "1" and "1.1"
* <li>ALWAYS: "1." and "1.1"
* </ul>
*
* @stable ICU 60
* @see NumberFormatter
*/
public static enum DecimalSeparatorDisplay {
/**
* Show the decimal separator when there are one or more digits to display after the
* separator, and do not show it otherwise. This is the default behavior.
*
* @stable ICU 60
* @see NumberFormatter
*/
AUTO,
/**
* Always show the decimal separator, even if there are no digits to display after the
* separator.
*
* @stable ICU 60
* @see NumberFormatter
*/
ALWAYS,
}
/**
* An enum declaring how to render trailing zeros.
*
* <ul>
* <li>AUTO: 0.90, 1.00, 1.10
* <li>HIDE_IF_WHOLE: 0.90, 1, 1.10
* </ul>
*
* @stable ICU 69
*/
public static enum TrailingZeroDisplay {
/**
* Display trailing zeros according to the settings for minimum fraction and significant
* digits.
*
* @stable ICU 69
*/
AUTO,
/**
* Same as AUTO, but hide trailing zeros after the decimal separator if they are all zero.
*
* @stable ICU 69
*/
HIDE_IF_WHOLE,
}
/**
* Use a default threshold of 3. This means that the third time .format() is called, the data
* structures get built using the "safe" code path. The first two calls to .format() will
* trigger the unsafe code path.
*/
static final long DEFAULT_THRESHOLD = 3;
/** Private constructor, not designed for instantiation. */
private NumberFormatter() {}
/**
* Call this method at the beginning of a NumberFormatter fluent chain in which the locale is
* not currently known at the call site.
*
* @return An {@link UnlocalizedNumberFormatter}, to be used for chaining.
* @stable ICU 60
*/
public static UnlocalizedNumberFormatter with() {
return BASE;
}
/**
* Call this method at the beginning of a NumberFormatter fluent chain in which the locale is
* known at the call site.
*
* @param locale The locale from which to load formats and symbols for number formatting.
* @return A {@link LocalizedNumberFormatter}, to be used for chaining.
* @stable ICU 60
*/
public static LocalizedNumberFormatter withLocale(Locale locale) {
return BASE.locale(locale);
}
/**
* Call this method at the beginning of a NumberFormatter fluent chain in which the locale is
* known at the call site.
*
* @param locale The locale from which to load formats and symbols for number formatting.
* @return A {@link LocalizedNumberFormatter}, to be used for chaining.
* @stable ICU 60
*/
public static LocalizedNumberFormatter withLocale(ULocale locale) {
return BASE.locale(locale);
}
/**
* Call this method at the beginning of a NumberFormatter fluent chain to create an instance
* based on a given number skeleton string.
*
* <p>For more information on number skeleton strings, see:
* https://unicode-org.github.io/icu/userguide/format_parse/numbers/skeletons.html
*
* @param skeleton The skeleton string off of which to base this NumberFormatter.
* @return An {@link UnlocalizedNumberFormatter}, to be used for chaining.
* @throws SkeletonSyntaxException If the given string is not a valid number formatting
* skeleton.
* @stable ICU 62
*/
public static UnlocalizedNumberFormatter forSkeleton(String skeleton) {
return NumberSkeletonImpl.getOrCreate(skeleton);
}
/**
* Note: In Java, since NumberPropertyMapper is package-private, this method is here so that it
* is accessible to tests.
*
* @internal
* @deprecated ICU 60 This API is ICU internal only.
*/
@Deprecated
public static UnlocalizedNumberFormatter fromDecimalFormat(
DecimalFormatProperties properties,
DecimalFormatSymbols symbols,
DecimalFormatProperties exportedProperties) {
return NumberPropertyMapper.create(properties, symbols, exportedProperties);
}
}