PluralRules

java.lang.Object
- ohos.global.icu.text.PluralRules

所有已实现的接口:

Serializable
```
public class PluralRules
extends Object
implements 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, C.11 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).
另请参阅:

序列化表格

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

嵌套类概要

嵌套类
限定符和类型类说明

static class PluralRules.PluralType
Type of plurals and PluralRules.

嵌套类
限定符和类型	类	说明
`static class`	`PluralRules.PluralType`	Type of plurals and PluralRules.

字段概要

字段
限定符和类型	字段	说明
`static PluralRules`	`DEFAULT`	The default rules that accept any number and return `KEYWORD_OTHER`.
`static String`	`KEYWORD_FEW`	Common name for the 'paucal' or other special plural form.
`static String`	`KEYWORD_MANY`	Common name for the arabic (11 to 99) plural form.
`static String`	`KEYWORD_ONE`	Common name for the 'singular' plural form.
`static String`	`KEYWORD_OTHER`	Common name for the default plural form.
`static String`	`KEYWORD_TWO`	Common name for the 'dual' plural form.
`static String`	`KEYWORD_ZERO`	Common name for the 'zero' plural form.
`static double`	`NO_UNIQUE_VALUE`	Value returned by `getUniqueKeywordValue(java.lang.String)` when there is no unique value to return.

方法概要

所有方法静态方法实例方法具体方法
限定符和类型	方法	说明
`static PluralRules`	`createRules(String description)`	Creates a PluralRules from a description if it is parsable, otherwise returns null.
`boolean`	`equals(Object rhs)`	Indicates whether some other object is "equal to" this one.
`boolean`	`equals(PluralRules rhs)`	Returns true if rhs is equal to this.
`static PluralRules`	`forLocale(Locale locale)`	Provides access to the predefined cardinal-number `PluralRules` for a given `Locale`.
`static PluralRules`	`forLocale(Locale locale, PluralRules.PluralType type)`	Provides access to the predefined `PluralRules` for a given `Locale` and the plural type.
`static PluralRules`	`forLocale(ULocale locale)`	Provides access to the predefined cardinal-number `PluralRules` for a given locale.
`static PluralRules`	`forLocale(ULocale locale, PluralRules.PluralType type)`	Provides access to the predefined `PluralRules` for a given locale and the plural type.
`Collection<Double>`	`getAllKeywordValues(String keyword)`	Returns all the values that trigger this keyword, or null if the number of such values is unlimited.
`Set<String>`	`getKeywords()`	Returns a set of all rule keywords used in this `PluralRules` object.
`Collection<Double>`	`getSamples(String keyword)`	Returns a list of integer values for which select() would return that keyword, or null if the keyword is not defined.
`double`	`getUniqueKeywordValue(String keyword)`	Returns the unique value that this keyword matches, or `NO_UNIQUE_VALUE` if the keyword matches multiple values or is not defined for this PluralRules.
`int`	`hashCode()`	Returns a hash code value for the object.
`static PluralRules`	`parseDescription(String description)`	Parses a plural rules description and returns a PluralRules.
`String`	`select(double number)`	Given a floating-point number, returns the keyword of the first rule that applies to the number.
`String`	`select(FormattedNumber number)`	Given a formatted number, returns the keyword of the first rule that applies to the number.
`String`	`toString()`	Returns a string representation of the object.

从类继承的方法 java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- 字段详细资料
  - DEFAULT
```
public static final PluralRules DEFAULT
```
    The default rules that accept any number and return KEYWORD_OTHER.
  - KEYWORD_FEW
```
public static final String KEYWORD_FEW
```
    Common name for the 'paucal' or other special plural form.
    
    另请参阅:
    
    常量字段值
  - KEYWORD_MANY
```
public static final String KEYWORD_MANY
```
    Common name for the arabic (11 to 99) plural form.
    
    另请参阅:
    
    常量字段值
  - KEYWORD_ONE
```
public static final String KEYWORD_ONE
```
    Common name for the 'singular' plural form.
    
    另请参阅:
    
    常量字段值
  - KEYWORD_OTHER
```
public static final String 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.
    
    另请参阅:
    
    常量字段值
  - KEYWORD_TWO
```
public static final String KEYWORD_TWO
```
    Common name for the 'dual' plural form.
    
    另请参阅:
    
    常量字段值
  - KEYWORD_ZERO
```
public static final String KEYWORD_ZERO
```
    Common name for the 'zero' plural form.
    
    另请参阅:
    
    常量字段值
  - NO_UNIQUE_VALUE
```
public static final double NO_UNIQUE_VALUE
```
    Value returned by getUniqueKeywordValue(java.lang.String) when there is no unique value to return.
    
    另请参阅:
    
    常量字段值
- 方法详细资料
  - parseDescription
```
public static PluralRules parseDescription(String description)
                                    throws ParseException
```
    Parses a plural rules description and returns a PluralRules.
    
    参数:
    
    description - the rule description.
    
    抛出:
    
    ParseException - if the description cannot be parsed. The exception index is typically not set, it will be -1.
  - createRules
```
public static PluralRules createRules(String description)
```
    Creates a PluralRules from a description if it is parsable, otherwise returns null.
    
    参数:
    
    description - the rule description.
    
    返回:
    
    the PluralRules
  - forLocale
```
public static PluralRules forLocale(ULocale locale)
```
    Provides access to the predefined cardinal-number PluralRules 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 http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
    
    参数:
    
    locale - The locale for which a PluralRules object is returned.
    
    返回:
    
    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.
  - forLocale
```
public static PluralRules forLocale(Locale locale)
```
    Provides access to the predefined cardinal-number PluralRules 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 http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
    
    参数:
    
    locale - The locale for which a PluralRules object is returned.
    
    返回:
    
    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.
  - forLocale
```
public static PluralRules forLocale(ULocale locale,
                                    PluralRules.PluralType type)
```
    Provides access to the predefined PluralRules 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 http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
    
    参数:
    
    locale - The locale for which a PluralRules object is returned.
    
    type - The plural type (e.g., cardinal or ordinal).
    
    返回:
    
    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.
  - forLocale
```
public static PluralRules forLocale(Locale locale,
                                    PluralRules.PluralType type)
```
    Provides access to the predefined PluralRules 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 http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html
    
    参数:
    
    locale - The locale for which a PluralRules object is returned.
    
    type - The plural type (e.g., cardinal or ordinal).
    
    返回:
    
    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.
  - hashCode
```
public int hashCode()
```
    Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.
    The general contract of hashCode is:
    - Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
    - If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
    - It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
    As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java™ programming language.)
    覆盖:
    
    hashCode 在类中 Object
    
    返回:
    
    a hash code value for this object.
    
    另请参阅:
    
    Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)
  - select
```
public String select(double number)
```
    Given a floating-point number, returns the keyword of the first rule that applies to the number.
    
    参数:
    
    number - The number for which the rule has to be determined.
    
    返回:
    
    The keyword of the selected rule.
  - select
```
public String select(FormattedNumber number)
```
    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, see NumberFormatter.
    
    参数:
    
    number - The number for which the rule has to be determined.
    
    返回:
    
    The keyword of the selected rule.
  - getKeywords
```
public Set<String> getKeywords()
```
    Returns a set of all rule keywords used in this PluralRules object. The rule "other" is always present by default.
    
    返回:
    
    The set of keywords.
  - getUniqueKeywordValue
```
public double getUniqueKeywordValue(String keyword)
```
    Returns the unique value that this keyword matches, or NO_UNIQUE_VALUE if the keyword matches multiple values or is not defined for this PluralRules.
    
    参数:
    
    keyword - the keyword to check for a unique value
    
    返回:
    
    The unique value for the keyword, or NO_UNIQUE_VALUE.
  - getAllKeywordValues
```
public Collection<Double> getAllKeywordValues(String keyword)
```
    Returns all the values that trigger this keyword, or null if the number of such values is unlimited.
    
    参数:
    
    keyword - the keyword
    
    返回:
    
    the values that trigger this keyword, or null. The returned collection is immutable. It will be empty if the keyword is not defined.
  - getSamples
```
public Collection<Double> getSamples(String keyword)
```
    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.
    
    参数:
    
    keyword - the keyword to test
    
    返回:
    
    a list of values matching the keyword.
  - toString
```
public String toString()
```
    Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.
    The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:
    getClass().getName() + '@' + Integer.toHexString(hashCode())
    覆盖:
    
    toString 在类中 Object
    
    返回:
    
    a string representation of the object.
  - equals
```
public boolean equals(Object rhs)
```
    Indicates whether some other object is "equal to" this one.
    The equals method implements an equivalence relation on non-null object references:
    - It is reflexive: for any non-null reference value x, x.equals(x) should return true.
    - It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
    - It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
    - It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
    - For any non-null reference value x, x.equals(null) should return false.
    The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).
    Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.
    覆盖:
    
    equals 在类中 Object
    
    参数:
    
    rhs - the reference object with which to compare.
    
    返回:
    
    true if this object is the same as the obj argument; false otherwise.
    
    另请参阅:
    
    Object.hashCode(), HashMap
  - equals
```
public boolean equals(PluralRules rhs)
```
    Returns true if rhs is equal to this.
    
    参数:
    
    rhs - the PluralRules to compare to.
    
    返回:
    
    true if this and rhs are equal.

类 PluralRules

嵌套类概要

字段概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

DEFAULT

KEYWORD_FEW

KEYWORD_MANY

KEYWORD_ONE

KEYWORD_OTHER

KEYWORD_TWO

KEYWORD_ZERO

NO_UNIQUE_VALUE

方法详细资料

parseDescription

createRules

forLocale

forLocale

forLocale

forLocale

hashCode

select

select

getKeywords

getUniqueKeywordValue

getAllKeywordValues

getSamples

toString

equals

equals