Class PluralRules
- All Implemented Interfaces:
Serializable
Defines rules for mapping non-negative numeric values onto a small set of keywords.
Rules are constructed from a text description, consisting of a series of keywords and conditions. The select(double)
method examines each condition in order and returns the keyword for the first condition that matches the number. If
none match, KEYWORD_OTHER
is returned.
A PluralRules object is immutable. It contains caches for sample values, but those are synchronized.
PluralRules is Serializable so that it can be used in formatters, which are serializable.
For more information, details, and tips for writing rules, see the LDML spec, Part 3.5 Language Plural Rules
Examples:
"one: n is 1; few: n in 2..4"
This defines two rules, for 'one' and 'few'. The condition for 'one' is "n is 1" which means that the number must be equal to 1 for this condition to pass. The condition for 'few' is "n in 2..4" which means that the number must be between 2 and 4 inclusive - and be an integer - for this condition to pass. All other numbers are assigned the keyword "other" by the default rule.
"zero: n is 0; one: n is 1; zero: n mod 100 in 1..19"
This illustrates that the same keyword can be defined multiple times. Each rule is examined in order, and the first keyword whose condition passes is the one returned. Also notes that a modulus is applied to n in the last rule. Thus its condition holds for 119, 219, 319...
"one: n is 1; few: n mod 10 in 2..4 and n mod 100 not in 12..14"
This illustrates conjunction and negation. The condition for 'few' has two parts, both of which must be met: "n mod 10 in 2..4" and "n mod 100 not in 12..14". The first part applies a modulus to n before the test as in the previous example. The second part applies a different modulus and also uses negation, thus it matches all numbers not in 12, 13, 14, 112, 113, 114, 212, 213, 214...
Syntax:
rules = rule (';' rule)* rule = keyword ':' condition keyword = <identifier> condition = and_condition ('or' and_condition)* and_condition = relation ('and' relation)* relation = not? expr not? rel not? range_list expr = ('n' | 'i' | 'f' | 'v' | 't') (mod value)? not = 'not' | '!' rel = 'in' | 'is' | '=' | '≠' | 'within' mod = 'mod' | '%' range_list = (range | value) (',' range_list)* value = digit+ digit = 0|1|2|3|4|5|6|7|8|9 range = value'..'value
Each not term inverts the meaning; however, there should not be more than one of them.
The i, f, t, and v values are defined as follows:
- i to be the integer digits.
- f to be the visible decimal digits, as an integer.
- t to be the visible decimal digits—without trailing zeros—as an integer.
- v to be the number of visible fraction digits.
- j is defined to only match integers. That is j is 3 fails if v != 0 (eg for 3.1 or 3.0).
Examples are in the following table:
n | i | f | v |
---|---|---|---|
1.0 | 1 | 0 | 1 |
1.00 | 1 | 0 | 2 |
1.3 | 1 | 3 | 1 |
1.03 | 1 | 3 | 2 |
1.23 | 1 | 23 | 2 |
An "identifier" is a sequence of characters that do not have the Unicode Pattern_Syntax or Pattern_White_Space properties.
The difference between 'in' and 'within' is that 'in' only includes integers in the specified range, while 'within' includes all values. Using 'within' with a range_list consisting entirely of values is the same as using 'in' (it's not an error).
- See Also:
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
Deprecated.This API is ICU internal only.static class
Deprecated.This API is ICU internal only.static class
Deprecated.This API is ICU internal only.static class
Deprecated.This API is ICU internal only.static interface
Deprecated.This API is ICU internal only.static enum
Status of the keyword for the rules, given a set of explicit values.static enum
Deprecated.This API is ICU internal only.static enum
Type of plurals and PluralRules.static enum
Deprecated.This API is ICU internal only. -
Field Summary
FieldsModifier and TypeFieldDescriptionstatic final PluralRules
The default rules that accept any number and returnKEYWORD_OTHER
.static final String
Common name for the 'paucal' or other special plural form.static final String
Common name for the arabic (11 to 99) plural form.static final String
Common name for the 'singular' plural form.static final String
Common name for the default plural form.static final String
Common name for the 'dual' plural form.static final String
Common name for the 'zero' plural form.static final double
Value returned bygetUniqueKeywordValue(java.lang.String)
when there is no unique value to return.static final com.ibm.icu.impl.number.DecimalQuantity
Deprecated.This API is ICU internal only. -
Method Summary
Modifier and TypeMethodDescriptionint
compareTo
(PluralRules other) Deprecated.internalboolean
computeLimited
(String keyword, PluralRules.SampleType sampleType) Deprecated.internalstatic PluralRules
createRules
(String description) Creates a PluralRules from a description if it is parsable, otherwise returns null.boolean
equals
(PluralRules rhs) Returns true if rhs is equal to this.boolean
static PluralRules
Provides access to the predefined cardinal-numberPluralRules
for a given locale.static PluralRules
forLocale
(ULocale locale, PluralRules.PluralType type) Provides access to the predefinedPluralRules
for a given locale and the plural type.static PluralRules
Provides access to the predefined cardinal-numberPluralRules
for a givenLocale
.static PluralRules
forLocale
(Locale locale, PluralRules.PluralType type) Provides access to the predefinedPluralRules
for a givenLocale
and the plural type.Collection
<com.ibm.icu.impl.number.DecimalQuantity> getAllKeywordDecimalQuantityValues
(String keyword) Deprecated.This API is ICU internal only.getAllKeywordValues
(String keyword) Returns all the values that trigger this keyword, or null if the number of such values is unlimited.Collection
<com.ibm.icu.impl.number.DecimalQuantity> getAllKeywordValues
(String keyword, PluralRules.SampleType type) Deprecated.This API is ICU internal only.static ULocale[]
Returns the set of locales for which PluralRules are known.Collection
<com.ibm.icu.impl.number.DecimalQuantity> getDecimalQuantitySamples
(String keyword) Deprecated.ICU internal onlyCollection
<com.ibm.icu.impl.number.DecimalQuantity> getDecimalQuantitySamples
(String keyword, PluralRules.SampleType sampleType) Deprecated.ICU internal onlygetDecimalSamples
(String keyword, PluralRules.SampleType sampleType) Deprecated.This API is ICU internal only.static ULocale
getFunctionalEquivalent
(ULocale locale, boolean[] isAvailable) Returns the 'functionally equivalent' locale with respect to plural rules.Returns a set of all rule keywords used in thisPluralRules
object.getKeywordStatus
(String keyword, int offset, Set<com.ibm.icu.impl.number.DecimalQuantity> explicits, Output<com.ibm.icu.impl.number.DecimalQuantity> uniqueValue) Find the status for the keyword, given a certain set of explicit values.getKeywordStatus
(String keyword, int offset, Set<com.ibm.icu.impl.number.DecimalQuantity> explicits, Output<com.ibm.icu.impl.number.DecimalQuantity> uniqueValue, PluralRules.SampleType sampleType) Deprecated.This API is ICU internal only.Deprecated.This API is ICU internal only.getSamples
(String keyword) Returns a list of integer values for which select() would return that keyword, or null if the keyword is not defined.getSamples
(String keyword, PluralRules.SampleType sampleType) Deprecated.ICU internal onlycom.ibm.icu.impl.number.DecimalQuantity
Deprecated.This API is ICU internal only.double
getUniqueKeywordValue
(String keyword) Returns the unique value that this keyword matches, orNO_UNIQUE_VALUE
if the keyword matches multiple values or is not defined for this PluralRules.int
hashCode()
boolean
isLimited
(String keyword, PluralRules.SampleType sampleType) Deprecated.internalboolean
matches
(PluralRules.FixedDecimal sample, String keyword) Deprecated.This API is ICU internal only.static PluralRules
newInternal
(String description, com.ibm.icu.impl.number.range.StandardPluralRanges ranges) Deprecated.This API is ICU internal only.static PluralRules
parseDescription
(String description) Parses a plural rules description and returns a PluralRules.select
(double number) Given a floating-point number, returns the keyword of the first rule that applies to the number.select
(double number, int countVisibleFractionDigits, long fractionaldigits) Deprecated.This API is ICU internal only.select
(FormattedNumber number) Given a formatted number, returns the keyword of the first rule that applies to the number.select
(FormattedNumberRange range) Given a formatted number range, returns the overall plural form of the range.select
(PluralRules.IFixedDecimal number) Deprecated.This API is ICU internal only.toString()
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Field Details
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KEYWORD_ZERO
Common name for the 'zero' plural form.- See Also:
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KEYWORD_ONE
Common name for the 'singular' plural form.- See Also:
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KEYWORD_TWO
Common name for the 'dual' plural form.- See Also:
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KEYWORD_FEW
Common name for the 'paucal' or other special plural form.- See Also:
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KEYWORD_MANY
Common name for the arabic (11 to 99) plural form.- See Also:
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KEYWORD_OTHER
Common name for the default plural form. This name is returned for values to which no other form in the rule applies. It can additionally be assigned rules of its own.- See Also:
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NO_UNIQUE_VALUE
public static final double NO_UNIQUE_VALUEValue returned bygetUniqueKeywordValue(java.lang.String)
when there is no unique value to return.- See Also:
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NO_UNIQUE_VALUE_DECIMAL_QUANTITY
@Deprecated public static final com.ibm.icu.impl.number.DecimalQuantity NO_UNIQUE_VALUE_DECIMAL_QUANTITYDeprecated.This API is ICU internal only.Value returned bygetUniqueKeywordDecimalQuantityValue(java.lang.String)
when there is no unique value to return. -
DEFAULT
The default rules that accept any number and returnKEYWORD_OTHER
.
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Method Details
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parseDescription
Parses a plural rules description and returns a PluralRules.- Parameters:
description
- the rule description.- Throws:
ParseException
- if the description cannot be parsed. The exception index is typically not set, it will be -1.
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createRules
Creates a PluralRules from a description if it is parsable, otherwise returns null.- Parameters:
description
- the rule description.- Returns:
- the PluralRules
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newInternal
@Deprecated public static PluralRules newInternal(String description, com.ibm.icu.impl.number.range.StandardPluralRanges ranges) throws ParseException Deprecated.This API is ICU internal only.- Throws:
ParseException
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forLocale
Provides access to the predefined cardinal-numberPluralRules
for a given locale. Same as forLocale(locale, PluralType.CARDINAL).ICU defines plural rules for many locales based on CLDR Language Plural Rules. For these predefined rules, see CLDR page at https://unicode-org.github.io/cldr-staging/charts/latest/supplemental/language_plural_rules.html
- Parameters:
locale
- The locale for which aPluralRules
object is returned.- Returns:
- The predefined
PluralRules
object for this locale. If there's no predefined rules for this locale, the rules for the closest parent in the locale hierarchy that has one will be returned. The final fallback always returns the default rules.
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forLocale
Provides access to the predefined cardinal-numberPluralRules
for a givenLocale
. Same as forLocale(locale, PluralType.CARDINAL).ICU defines plural rules for many locales based on CLDR Language Plural Rules. For these predefined rules, see CLDR page at https://unicode-org.github.io/cldr-staging/charts/latest/supplemental/language_plural_rules.html
- Parameters:
locale
- The locale for which aPluralRules
object is returned.- Returns:
- The predefined
PluralRules
object for this locale. If there's no predefined rules for this locale, the rules for the closest parent in the locale hierarchy that has one will be returned. The final fallback always returns the default rules.
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forLocale
Provides access to the predefinedPluralRules
for a given locale and the plural type.ICU defines plural rules for many locales based on CLDR Language Plural Rules. For these predefined rules, see CLDR page at https://unicode-org.github.io/cldr-staging/charts/latest/supplemental/language_plural_rules.html
- Parameters:
locale
- The locale for which aPluralRules
object is returned.type
- The plural type (e.g., cardinal or ordinal).- Returns:
- The predefined
PluralRules
object for this locale. If there's no predefined rules for this locale, the rules for the closest parent in the locale hierarchy that has one will be returned. The final fallback always returns the default rules.
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forLocale
Provides access to the predefinedPluralRules
for a givenLocale
and the plural type.ICU defines plural rules for many locales based on CLDR Language Plural Rules. For these predefined rules, see CLDR page at https://unicode-org.github.io/cldr-staging/charts/latest/supplemental/language_plural_rules.html
- Parameters:
locale
- The locale for which aPluralRules
object is returned.type
- The plural type (e.g., cardinal or ordinal).- Returns:
- The predefined
PluralRules
object for this locale. If there's no predefined rules for this locale, the rules for the closest parent in the locale hierarchy that has one will be returned. The final fallback always returns the default rules.
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hashCode
public int hashCode() -
select
Given a floating-point number, returns the keyword of the first rule that applies to the number.- Parameters:
number
- The number for which the rule has to be determined.- Returns:
- The keyword of the selected rule.
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select
Given a formatted number, returns the keyword of the first rule that applies to the number. A FormattedNumber allows you to specify an exponent or trailing zeros, which can affect the plural category. To get a FormattedNumber, seeNumberFormatter
.- Parameters:
number
- The number for which the rule has to be determined.- Returns:
- The keyword of the selected rule.
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select
Given a formatted number range, returns the overall plural form of the range. For example, "3-5" returns "other" in English. To get a FormattedNumberRange, seeNumberRangeFormatter
. This method only works if PluralRules was created with a locale. If it was created from PluralRules.createRules(), or if it was deserialized, this method throws UnsupportedOperationException.- Parameters:
range
- The number range onto which the rules will be applied.- Returns:
- The keyword of the selected rule.
- Throws:
UnsupportedOperationException
- If called on an instance without plural ranges data.
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select
@Deprecated public String select(double number, int countVisibleFractionDigits, long fractionaldigits) Deprecated.This API is ICU internal only.Given a number, returns the keyword of the first rule that applies to the number.- Parameters:
number
- The number for which the rule has to be determined.- Returns:
- The keyword of the selected rule.
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select
Deprecated.This API is ICU internal only.Given a number information, returns the keyword of the first rule that applies to the number.- Parameters:
number
- The number information for which the rule has to be determined.- Returns:
- The keyword of the selected rule.
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matches
Deprecated.This API is ICU internal only.Given a number information, and keyword, return whether the keyword would match the number.- Parameters:
sample
- The number information for which the rule has to be determined.keyword
- The keyword to filter on
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getKeywords
Returns a set of all rule keywords used in thisPluralRules
object. The rule "other" is always present by default.- Returns:
- The set of keywords.
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getUniqueKeywordValue
Returns the unique value that this keyword matches, orNO_UNIQUE_VALUE
if the keyword matches multiple values or is not defined for this PluralRules.- Parameters:
keyword
- the keyword to check for a unique value- Returns:
- The unique value for the keyword, or NO_UNIQUE_VALUE.
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getUniqueKeywordDecimalQuantityValue
@Deprecated public com.ibm.icu.impl.number.DecimalQuantity getUniqueKeywordDecimalQuantityValue(String keyword) Deprecated.This API is ICU internal only.Returns the unique value that this keyword matches, orNO_UNIQUE_VALUE
if the keyword matches multiple values or is not defined for this PluralRules.- Parameters:
keyword
- the keyword to check for a unique value
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getAllKeywordValues
Returns all the values that trigger this keyword, or null if the number of such values is unlimited.- Parameters:
keyword
- the keyword- Returns:
- the values that trigger this keyword, or null. The returned collection is immutable. It will be empty if the keyword is not defined.
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getAllKeywordDecimalQuantityValues
@Deprecated public Collection<com.ibm.icu.impl.number.DecimalQuantity> getAllKeywordDecimalQuantityValues(String keyword) Deprecated.This API is ICU internal only.Returns all the values that trigger this keyword, or null if the number of such values is unlimited.- Parameters:
keyword
- the keyword- Returns:
- the values that trigger this keyword, or null. The returned collection is immutable. It will be empty if the keyword is not defined.
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getAllKeywordValues
@Deprecated public Collection<com.ibm.icu.impl.number.DecimalQuantity> getAllKeywordValues(String keyword, PluralRules.SampleType type) Deprecated.This API is ICU internal only.Returns all the values that trigger this keyword, or null if the number of such values is unlimited.- Parameters:
keyword
- the keywordtype
- the type of samples requested, INTEGER or DECIMAL- Returns:
- the values that trigger this keyword, or null. The returned collection is immutable. It will be empty if the keyword is not defined.
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getSamples
Returns a list of integer values for which select() would return that keyword, or null if the keyword is not defined. The returned collection is unmodifiable. The returned list is not complete, and there might be additional values that would return the keyword.- Parameters:
keyword
- the keyword to test- Returns:
- a list of values matching the keyword.
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getDecimalQuantitySamples
@Deprecated public Collection<com.ibm.icu.impl.number.DecimalQuantity> getDecimalQuantitySamples(String keyword) Deprecated.ICU internal onlyReturns a list of integer values for which select() would return that keyword, or null if the keyword is not defined. The returned collection is unmodifiable. The returned list is not complete, and there might be additional values that would return the keyword.- Parameters:
keyword
- the keyword to test- Returns:
- a list of values matching the keyword.
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getSamples
Deprecated.ICU internal onlyReturns a list of values for which select() would return that keyword, or null if the keyword is not defined. The returned collection is unmodifiable. The returned list is not complete, and there might be additional values that would return the keyword. The keyword might be defined, and yet have an empty set of samples, IF there are samples for the other sampleType.- Parameters:
keyword
- the keyword to testsampleType
- the type of samples requested, INTEGER or DECIMAL- Returns:
- a list of values matching the keyword.
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getDecimalQuantitySamples
@Deprecated public Collection<com.ibm.icu.impl.number.DecimalQuantity> getDecimalQuantitySamples(String keyword, PluralRules.SampleType sampleType) Deprecated.ICU internal onlyReturns a list of values for which select() would return that keyword, or null if the keyword is not defined. The returned collection is unmodifiable. The returned list is not complete, and there might be additional values that would return the keyword. The keyword might be defined, and yet have an empty set of samples, IF there are samples for the other sampleType.- Parameters:
keyword
- the keyword to testsampleType
- the type of samples requested, INTEGER or DECIMAL- Returns:
- a list of values matching the keyword.
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getDecimalSamples
@Deprecated public PluralRules.DecimalQuantitySamples getDecimalSamples(String keyword, PluralRules.SampleType sampleType) Deprecated.This API is ICU internal only.Returns a list of values for which select() would return that keyword, or null if the keyword is not defined or no samples are available. The returned collection is unmodifiable. The returned list is not complete, and there might be additional values that would return the keyword.- Parameters:
keyword
- the keyword to testsampleType
- the type of samples requested, INTEGER or DECIMAL- Returns:
- a list of values matching the keyword.
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getAvailableULocales
Returns the set of locales for which PluralRules are known.- Returns:
- the set of locales for which PluralRules are known, as a list
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getFunctionalEquivalent
Returns the 'functionally equivalent' locale with respect to plural rules. Calling PluralRules.forLocale with the functionally equivalent locale, and with the provided locale, returns rules that behave the same.
All locales with the same functionally equivalent locale have plural rules that behave the same. This is not exhaustive; there may be other locales whose plural rules behave the same that do not have the same equivalent locale.- Parameters:
locale
- the locale to checkisAvailable
- if not null and of length > 0, this will hold 'true' at index 0 if locale is directly defined (without fallback) as having plural rules- Returns:
- the functionally-equivalent locale
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toString
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equals
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equals
Returns true if rhs is equal to this.- Parameters:
rhs
- the PluralRules to compare to.- Returns:
- true if this and rhs are equal.
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getKeywordStatus
public PluralRules.KeywordStatus getKeywordStatus(String keyword, int offset, Set<com.ibm.icu.impl.number.DecimalQuantity> explicits, Output<com.ibm.icu.impl.number.DecimalQuantity> uniqueValue) Find the status for the keyword, given a certain set of explicit values.- Parameters:
keyword
- the particular keyword (call rules.getKeywords() to get the valid ones)offset
- the offset used, or 0.0d if not. Internally, the offset is subtracted from each explicit value before checking against the keyword values.explicits
- a set ofDecimalQuantity
s that are used explicitly (eg [=0], "[=1]"). May be empty or null.uniqueValue
- If non null, set to the unique value.- Returns:
- the KeywordStatus
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getKeywordStatus
@Deprecated public PluralRules.KeywordStatus getKeywordStatus(String keyword, int offset, Set<com.ibm.icu.impl.number.DecimalQuantity> explicits, Output<com.ibm.icu.impl.number.DecimalQuantity> uniqueValue, PluralRules.SampleType sampleType) Deprecated.This API is ICU internal only.Find the status for the keyword, given a certain set of explicit values.- Parameters:
keyword
- the particular keyword (call rules.getKeywords() to get the valid ones)offset
- the offset used, or 0.0d if not. Internally, the offset is subtracted from each explicit value before checking against the keyword values.explicits
- a set ofDecimalQuantity
s that are used explicitly (eg [=0], "[=1]"). May be empty or null.uniqueValue
- If non null, set to the unique value.sampleType
- request KeywordStatus relative to INTEGER or DECIMAL values- Returns:
- the KeywordStatus
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getRules
Deprecated.This API is ICU internal only. -
compareTo
Deprecated.internal -
isLimited
Deprecated.internal -
computeLimited
Deprecated.internal
-