com.ibm.icu.number

Class NumberFormatter

java.lang.Object

com.ibm.icu.number.NumberFormatter

public final class NumberFormatter
extends Object

All-in-one formatter for localized numbers, currencies, and units. For a full list of options, see NumberFormatterSettings.

 // 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
 

This API offers more features than DecimalFormat and is geared toward new users of ICU.

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.

 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"
 

This API is based on the fluent design pattern popularized by libraries such as Google's Guava. For extensive details on the design of this API, read the design doc.

Note: To format monetary/currency values, specify the currency in the `.unit()` function.

Author:

Shane Carr

Status:

Stable ICU 60.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NumberFormatter.DecimalSeparatorDisplay An enum declaring how to render the decimal separator.
static class	NumberFormatter.GroupingStrategy 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).
static class	NumberFormatter.RoundingPriority An enum declaring how to resolve conflicts between maximum fraction digits and maximum significant digits.
static class	NumberFormatter.SignDisplay An enum declaring how to denote positive and negative numbers.
static class	NumberFormatter.TrailingZeroDisplay An enum declaring how to render trailing zeros.
static class	NumberFormatter.UnitWidth An enum declaring how to render units, including currencies.

Method Summary

Modifier and Type	Method and Description
static UnlocalizedNumberFormatter	forSkeleton(String skeleton) Call this method at the beginning of a NumberFormatter fluent chain to create an instance based on a given number skeleton string.
static UnlocalizedNumberFormatter	fromDecimalFormat(com.ibm.icu.impl.number.DecimalFormatProperties properties, DecimalFormatSymbols symbols, com.ibm.icu.impl.number.DecimalFormatProperties exportedProperties) Deprecated. ICU 60 This API is ICU internal only.
static UnlocalizedNumberFormatter	with() Call this method at the beginning of a NumberFormatter fluent chain in which the locale is not currently known at the call site.
static LocalizedNumberFormatter	withLocale(Locale locale) Call this method at the beginning of a NumberFormatter fluent chain in which the locale is known at the call site.
static LocalizedNumberFormatter	withLocale(ULocale locale) Call this method at the beginning of a NumberFormatter fluent chain in which the locale is known at the call site.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

with

public static UnlocalizedNumberFormatter with()

Call this method at the beginning of a NumberFormatter fluent chain in which the locale is not currently known at the call site.

Returns:

An UnlocalizedNumberFormatter, to be used for chaining.

Status:

Stable ICU 60.

withLocale

public static LocalizedNumberFormatter withLocale(Locale locale)

Call this method at the beginning of a NumberFormatter fluent chain in which the locale is known at the call site.

Parameters:

locale - The locale from which to load formats and symbols for number formatting.

Returns:

A LocalizedNumberFormatter, to be used for chaining.

Status:

Stable ICU 60.

withLocale

public static LocalizedNumberFormatter withLocale(ULocale locale)

Call this method at the beginning of a NumberFormatter fluent chain in which the locale is known at the call site.

Parameters:

locale - The locale from which to load formats and symbols for number formatting.

Returns:

A LocalizedNumberFormatter, to be used for chaining.

Status:

Stable ICU 60.

forSkeleton

public static UnlocalizedNumberFormatter forSkeleton(String skeleton)

Call this method at the beginning of a NumberFormatter fluent chain to create an instance based on a given number skeleton string. For more information on number skeleton strings, see: https://unicode-org.github.io/icu/userguide/format_parse/numbers/skeletons.html

Parameters:

skeleton - The skeleton string off of which to base this NumberFormatter.

Returns:

An UnlocalizedNumberFormatter, to be used for chaining.

Throws:

SkeletonSyntaxException - If the given string is not a valid number formatting skeleton.

Status:

Stable ICU 62.

fromDecimalFormat

@Deprecated
public static UnlocalizedNumberFormatter fromDecimalFormat(com.ibm.icu.impl.number.DecimalFormatProperties properties,
                                                                       DecimalFormatSymbols symbols,
                                                                       com.ibm.icu.impl.number.DecimalFormatProperties exportedProperties)

Deprecated. ICU 60 This API is ICU internal only.

Note: In Java, since NumberPropertyMapper is package-private, this method is here so that it is accessible to tests.

Status:

Internal. This API is ICU internal only.