RuleBasedCollator (ICU4J 76)

java.lang.Object
- com.ibm.icu.text.Collator
- - com.ibm.icu.text.RuleBasedCollator

All Implemented Interfaces:

Freezable<Collator>, Cloneable, Comparator<Object>
```
public final class RuleBasedCollator
extends Collator
```
RuleBasedCollator is a concrete subclass of Collator. It allows customization of the Collator via user-specified rule sets. RuleBasedCollator is designed to be fully compliant to the Unicode Collation Algorithm (UCA) and conforms to ISO 14651.
A Collator is thread-safe only when frozen. See isFrozen() and Freezable.
Users are strongly encouraged to read the User Guide for more information about the collation service before using this class.
Create a RuleBasedCollator from a locale by calling the getInstance(Locale) factory method in the base class Collator. Collator.getInstance(Locale) creates a RuleBasedCollator object based on the collation rules defined by the argument locale. If a customized collation ordering or attributes is required, use the RuleBasedCollator(String) constructor with the appropriate rules. The customized RuleBasedCollator will base its ordering on the CLDR root collation, while re-adjusting the attributes and orders of the characters in the specified rule accordingly.
RuleBasedCollator provides correct collation orders for most locales supported in ICU. If specific data for a locale is not available, the orders eventually falls back to the CLDR root sort order.
For information about the collation rule syntax and details about customization, please refer to the Collation customization section of the User Guide.
Note that there are some differences between the Collation rule syntax used in Java and ICU4J:
- According to the JDK documentation:
  Modifier '!' : Turns on Thai/Lao vowel-consonant swapping. If this rule is in force when a Thai vowel of the range \U0E40-\U0E44 precedes a Thai consonant of the range \U0E01-\U0E2E OR a Lao vowel of the range \U0EC0-\U0EC4 precedes a Lao consonant of the range \U0E81-\U0EAE then the vowel is placed after the consonant for collation purposes.
  If a rule is without the modifier '!', the Thai/Lao vowel-consonant swapping is not turned on.
  ICU4J's RuleBasedCollator does not support turning off the Thai/Lao vowel-consonant swapping, since the UCA clearly states that it has to be supported to ensure a correct sorting order. If a '!' is encountered, it is ignored.
- As mentioned in the documentation of the base class Collator, compatibility decomposition mode is not supported.
Examples
Creating Customized RuleBasedCollators:
```
 String simple = "& a < b < c < d";
 RuleBasedCollator simpleCollator = new RuleBasedCollator(simple);

 String norwegian = "& a , A < b , B < c , C < d , D < e , E "
                    + "< f , F < g , G < h , H < i , I < j , "
                    + "J < k , K < l , L < m , M < n , N < "
                    + "o , O < p , P < q , Q <r , R <s , S < "
                    + "t , T < u , U < v , V < w , W < x , X "
                    + "< y , Y < z , Z < \u00E5 = a\u030A "
                    + ", \u00C5 = A\u030A ; aa , AA < \u00E6 "
                    + ", \u00C6 < \u00F8 , \u00D8";
 RuleBasedCollator norwegianCollator = new RuleBasedCollator(norwegian);
 
```
Concatenating rules to combine Collators:
```
 // Create an en_US Collator object
 RuleBasedCollator en_USCollator = (RuleBasedCollator)
     Collator.getInstance(new Locale("en", "US", ""));
 // Create a da_DK Collator object
 RuleBasedCollator da_DKCollator = (RuleBasedCollator)
     Collator.getInstance(new Locale("da", "DK", ""));
 // Combine the two
 // First, get the collation rules from en_USCollator
 String en_USRules = en_USCollator.getRules();
 // Second, get the collation rules from da_DKCollator
 String da_DKRules = da_DKCollator.getRules();
 RuleBasedCollator newCollator =
                             new RuleBasedCollator(en_USRules + da_DKRules);
 // newCollator has the combined rules
 
```
Making changes to an existing RuleBasedCollator to create a new Collator object, by appending changes to the existing rule:
```
 // Create a new Collator object with additional rules
 String addRules = "& C < ch, cH, Ch, CH";
 RuleBasedCollator myCollator =
     new RuleBasedCollator(en_USCollator.getRules() + addRules);
 // myCollator contains the new rules
 
```
How to change the order of non-spacing accents:
```
 // old rule with main accents
 String oldRules = "= \u0301 ; \u0300 ; \u0302 ; \u0308 "
                 + "; \u0327 ; \u0303 ; \u0304 ; \u0305 "
                 + "; \u0306 ; \u0307 ; \u0309 ; \u030A "
                 + "; \u030B ; \u030C ; \u030D ; \u030E "
                 + "; \u030F ; \u0310 ; \u0311 ; \u0312 "
                 + "< a , A ; ae, AE ; \u00e6 , \u00c6 "
                 + "< b , B < c, C < e, E & C < d , D";
 // change the order of accent characters
 String addOn = "& \u0300 ; \u0308 ; \u0302";
 RuleBasedCollator myCollator = new RuleBasedCollator(oldRules + addOn);
 
```
Putting in a new primary ordering before the default setting, e.g. sort English characters before or after Japanese characters in the Japanese Collator:
```
 // get en_US Collator rules
 RuleBasedCollator en_USCollator
                        = (RuleBasedCollator)Collator.getInstance(Locale.US);
 // add a few Japanese characters to sort before English characters
 // suppose the last character before the first base letter 'a' in
 // the English collation rule is \u2212
 String jaString = "& \u2212 <\u3041, \u3042 <\u3043, "
                   + "\u3044";
 RuleBasedCollator myJapaneseCollator
              = new RuleBasedCollator(en_USCollator.getRules() + jaString);
 
```
This class is not subclassable
Author:

Syn Wee Quek

Status:
Stable ICU 2.8.

Nested Class Summary
- Nested classes/interfaces inherited from class com.ibm.icu.text.Collator
  Collator.CollatorFactory, Collator.ReorderCodes

Field Summary
- Fields inherited from class com.ibm.icu.text.Collator
  CANONICAL_DECOMPOSITION, FULL_DECOMPOSITION, IDENTICAL, NO_DECOMPOSITION, PRIMARY, QUATERNARY, SECONDARY, TERTIARY

Constructor Summary

Constructors
Constructor and Description

RuleBasedCollator(String rules)
Constructor that takes the argument rules for customization.

Constructors
Constructor and Description
`RuleBasedCollator(String rules)` Constructor that takes the argument rules for customization.

Method Summary

All Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`Object`	`clone()` Clones the RuleBasedCollator
`RuleBasedCollator`	`cloneAsThawed()` Provides for the clone operation.
`int`	`compare(String source, String target)` Compares the source text String to the target text String according to the collation rules, strength and decomposition mode for this RuleBasedCollator.
`protected int`	`doCompare(CharSequence left, CharSequence right)` Deprecated. This API is ICU internal only.
`boolean`	`equals(Object obj)` Compares the equality of two Collator objects.
`Collator`	`freeze()` Freezes the collator.
`CollationElementIterator`	`getCollationElementIterator(CharacterIterator source)` Return a CollationElementIterator for the given CharacterIterator.
`CollationElementIterator`	`getCollationElementIterator(String source)` Return a CollationElementIterator for the given String.
`CollationElementIterator`	`getCollationElementIterator(UCharacterIterator source)` Return a CollationElementIterator for the given UCharacterIterator.
`CollationKey`	`getCollationKey(String source)` Get a Collation key for the argument String source from this RuleBasedCollator.
`void`	`getContractionsAndExpansions(UnicodeSet contractions, UnicodeSet expansions, boolean addPrefixes)` Gets unicode sets containing contractions and/or expansions of a collator
`int`	`getDecomposition()` Returns the decomposition mode of this Collator.
`ULocale`	`getLocale(ULocale.Type type)` [icu] Returns the locale that was used to create this object, or null.
`int`	`getMaxVariable()` [icu] Returns the maximum reordering group whose characters are affected by the alternate handling behavior.
`boolean`	`getNumericCollation()` Method to retrieve the numeric collation value.
`RawCollationKey`	`getRawCollationKey(String source, RawCollationKey key)` Gets the simpler form of a CollationKey for the String source following the rules of this Collator and stores the result into the user provided argument key.
`int[]`	`getReorderCodes()` Retrieves the reordering codes for this collator.
`String`	`getRules()` Gets the collation tailoring rules for this RuleBasedCollator.
`String`	`getRules(boolean fullrules)` Returns current rules.
`int`	`getStrength()` Returns this Collator's strength attribute.
`UnicodeSet`	`getTailoredSet()` Get a UnicodeSet that contains all the characters and sequences tailored in this collator.
`VersionInfo`	`getUCAVersion()` Get the UCA version of this collator object.
`int`	`getVariableTop()` [icu] Gets the variable top value of a Collator.
`VersionInfo`	`getVersion()` Get the version of this collator object.
`int`	`hashCode()` Generates a unique hash code for this RuleBasedCollator.
`long[]`	`internalGetCEs(CharSequence str)` Deprecated. This API is ICU internal only.
`boolean`	`isAlternateHandlingShifted()` Checks if the alternate handling behavior is the UCA defined SHIFTED or NON_IGNORABLE.
`boolean`	`isCaseLevel()` Checks if case level is set to true.
`boolean`	`isFrenchCollation()` Checks if French Collation is set to true.
`boolean`	`isFrozen()` Determines whether the object has been frozen or not.
`boolean`	`isHiraganaQuaternary()` Deprecated. ICU 50 Implementation detail, cannot be set via API, was removed from implementation.
`boolean`	`isLowerCaseFirst()` Return true if a lowercase character is sorted before the corresponding uppercase character.
`boolean`	`isUpperCaseFirst()` Return true if an uppercase character is sorted before the corresponding lowercase character.
`void`	`setAlternateHandlingDefault()` Sets the alternate handling mode to the initial mode set during construction of the RuleBasedCollator.
`void`	`setAlternateHandlingShifted(boolean shifted)` Sets the alternate handling for QUATERNARY strength to be either shifted or non-ignorable.
`void`	`setCaseFirstDefault()` Sets the case first mode to the initial mode set during construction of the RuleBasedCollator.
`void`	`setCaseLevel(boolean flag)` When case level is set to true, an additional weight is formed between the SECONDARY and TERTIARY weight, known as the case level.
`void`	`setCaseLevelDefault()` Sets the case level mode to the initial mode set during construction of the RuleBasedCollator.
`void`	`setDecomposition(int decomposition)` Sets the decomposition mode of this Collator.
`void`	`setDecompositionDefault()` Sets the decomposition mode to the initial mode set during construction of the RuleBasedCollator.
`void`	`setFrenchCollation(boolean flag)` Sets the mode for the direction of SECONDARY weights to be used in French collation.
`void`	`setFrenchCollationDefault()` Sets the French collation mode to the initial mode set during construction of the RuleBasedCollator.
`void`	`setHiraganaQuaternary(boolean flag)` Deprecated. ICU 50 Implementation detail, cannot be set via API, was removed from implementation.
`void`	`setHiraganaQuaternaryDefault()` Deprecated. ICU 50 Implementation detail, cannot be set via API, was removed from implementation.
`void`	`setLowerCaseFirst(boolean lowerfirst)` Sets the orders of lower cased characters to sort before upper cased characters, in strength TERTIARY.
`RuleBasedCollator`	`setMaxVariable(int group)` [icu] Sets the variable top to the top of the specified reordering group.
`void`	`setNumericCollation(boolean flag)` [icu] When numeric collation is turned on, this Collator makes substrings of digits sort according to their numeric values.
`void`	`setNumericCollationDefault()` Method to set numeric collation to its default value.
`void`	`setReorderCodes(int... order)` Sets the reordering codes for this collator.
`void`	`setStrength(int newStrength)` Sets this Collator's strength attribute.
`void`	`setStrengthDefault()` Sets the collation strength to the initial mode set during the construction of the RuleBasedCollator.
`void`	`setUpperCaseFirst(boolean upperfirst)` Sets whether uppercase characters sort before lowercase characters or vice versa, in strength TERTIARY.
`void`	`setVariableTop(int varTop)` Deprecated. ICU 53 Call setMaxVariable() instead.
`int`	`setVariableTop(String varTop)` Deprecated. ICU 53 Call `setMaxVariable(int)` instead.

Methods inherited from class com.ibm.icu.text.Collator
compare, equals, getAvailableLocales, getAvailableULocales, getDisplayName, getDisplayName, getDisplayName, getDisplayName, getEquivalentReorderCodes, getFunctionalEquivalent, getFunctionalEquivalent, getInstance, getInstance, getInstance, getKeywords, getKeywordValues, getKeywordValuesForLocale, registerFactory, registerInstance, setStrength2, unregister

Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Comparator
comparing, comparing, comparingDouble, comparingInt, comparingLong, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

- Constructor Detail
  - RuleBasedCollator
```
public RuleBasedCollator(String rules)
                  throws Exception
```
    Constructor that takes the argument rules for customization. The collator will be based on the CLDR root collation, with the attributes and re-ordering of the characters specified in the argument rules.
    See the User Guide's section on Collation Customization for details on the rule syntax.
    
    Parameters:
    
    rules - the collation rules to build the collation table from.
    
    Throws:
    
    ParseException - and IOException thrown. ParseException thrown when argument rules have an invalid syntax. IOException thrown when an error occurred while reading internal data.
    
    Exception
    
    Status:
    Stable ICU 2.8.
- Method Detail
  - clone
```
public Object clone()
             throws CloneNotSupportedException
```
    Clones the RuleBasedCollator
    
    Overrides:
    
    clone in class Collator
    
    Returns:
    
    a new instance of this RuleBasedCollator object
    
    Throws:
    
    CloneNotSupportedException
    
    Status:
    Stable ICU 2.8.
  - getCollationElementIterator
```
public CollationElementIterator getCollationElementIterator(String source)
```
    Return a CollationElementIterator for the given String.
    
    See Also:
    
    CollationElementIterator
    
    Status:
    Stable ICU 2.8.
  - getCollationElementIterator
```
public CollationElementIterator getCollationElementIterator(CharacterIterator source)
```
    Return a CollationElementIterator for the given CharacterIterator. The source iterator's integrity will be preserved since a new copy will be created for use.
    
    See Also:
    
    CollationElementIterator
    
    Status:
    Stable ICU 2.8.
  - getCollationElementIterator
```
public CollationElementIterator getCollationElementIterator(UCharacterIterator source)
```
    Return a CollationElementIterator for the given UCharacterIterator. The source iterator's integrity will be preserved since a new copy will be created for use.
    
    See Also:
    
    CollationElementIterator
    
    Status:
    Stable ICU 2.8.
  - isFrozen
```
public boolean isFrozen()
```
    Determines whether the object has been frozen or not.
    An unfrozen Collator is mutable and not thread-safe. A frozen Collator is immutable and thread-safe.
    
    Specified by:
    
    isFrozen in interface Freezable<Collator>
    
    Overrides:
    
    isFrozen in class Collator
    
    Status:
    Stable ICU 4.8.
  - freeze
```
public Collator freeze()
```
    Freezes the collator.
    
    Specified by:
    
    freeze in interface Freezable<Collator>
    
    Overrides:
    
    freeze in class Collator
    
    Returns:
    
    the collator itself.
    
    Status:
    Stable ICU 4.8.
  - cloneAsThawed
```
public RuleBasedCollator cloneAsThawed()
```
    Provides for the clone operation. Any clone is initially unfrozen.
    
    Specified by:
    
    cloneAsThawed in interface Freezable<Collator>
    
    Overrides:
    
    cloneAsThawed in class Collator
    
    Status:
    Stable ICU 4.8.
  - setHiraganaQuaternary
```
@Deprecated
public void setHiraganaQuaternary(boolean flag)
```
    Deprecated. ICU 50 Implementation detail, cannot be set via API, was removed from implementation.
    
    Sets the Hiragana Quaternary mode to be on or off. When the Hiragana Quaternary mode is turned on, the collator positions Hiragana characters before all non-ignorable characters in QUATERNARY strength. This is to produce a correct JIS collation order, distinguishing between Katakana and Hiragana characters.
    This attribute was an implementation detail of the CLDR Japanese tailoring. Since ICU 50, this attribute is not settable any more via API functions. Since CLDR 25/ICU 53, explicit quaternary relations are used to achieve the same Japanese sort order.
    
    Parameters:
    
    flag - true if Hiragana Quaternary mode is to be on, false otherwise
    
    See Also:
    
    setHiraganaQuaternaryDefault(), isHiraganaQuaternary()
  - setHiraganaQuaternaryDefault
```
@Deprecated
public void setHiraganaQuaternaryDefault()
```
    Deprecated. ICU 50 Implementation detail, cannot be set via API, was removed from implementation.
    
    Sets the Hiragana Quaternary mode to the initial mode set during construction of the RuleBasedCollator. See setHiraganaQuaternary(boolean) for more details.
    This attribute was an implementation detail of the CLDR Japanese tailoring. Since ICU 50, this attribute is not settable any more via API functions. Since CLDR 25/ICU 53, explicit quaternary relations are used to achieve the same Japanese sort order.
    
    See Also:
    
    setHiraganaQuaternary(boolean), isHiraganaQuaternary()
  - setUpperCaseFirst
```
public void setUpperCaseFirst(boolean upperfirst)
```
    Sets whether uppercase characters sort before lowercase characters or vice versa, in strength TERTIARY. If false, lowercase characters sort before uppercase characters. If true, sort upper case characters first. The default setting in a Collator object depends on the locale data loaded from the resources. For most locales, the default is false, but for others, such as "da" or "mt", the default could be true.
    
    Parameters:
    
    upperfirst - true to sort uppercase characters before lowercase characters, false to sort lowercase characters before uppercase characters
    
    See Also:
    
    isLowerCaseFirst(), isUpperCaseFirst(), setLowerCaseFirst(boolean), setCaseFirstDefault()
    
    Status:
    Stable ICU 2.8.
  - setLowerCaseFirst
```
public void setLowerCaseFirst(boolean lowerfirst)
```
    Sets the orders of lower cased characters to sort before upper cased characters, in strength TERTIARY. If true is set, the RuleBasedCollator will sort lower cased characters before the upper cased ones. Otherwise, if false is set, the RuleBasedCollator will ignore case preferences. The default default setting in a Collator object depends on the locale data loaded from the resources.
    
    Parameters:
    
    lowerfirst - true for sorting lower cased characters before upper cased characters, false to ignore case preferences.
    
    See Also:
    
    isLowerCaseFirst(), isUpperCaseFirst(), setUpperCaseFirst(boolean), setCaseFirstDefault()
    
    Status:
    Stable ICU 2.8.
  - setCaseFirstDefault
```
public final void setCaseFirstDefault()
```
    Sets the case first mode to the initial mode set during construction of the RuleBasedCollator. See setUpperCaseFirst(boolean) and setLowerCaseFirst(boolean) for more details.
    
    See Also:
    
    isLowerCaseFirst(), isUpperCaseFirst(), setLowerCaseFirst(boolean), setUpperCaseFirst(boolean)
    
    Status:
    Stable ICU 2.8.
  - setAlternateHandlingDefault
```
public void setAlternateHandlingDefault()
```
    Sets the alternate handling mode to the initial mode set during construction of the RuleBasedCollator. See setAlternateHandling(boolean) for more details.
    
    See Also:
    
    setAlternateHandlingShifted(boolean), isAlternateHandlingShifted()
    
    Status:
    Stable ICU 2.8.
  - setCaseLevelDefault
```
public void setCaseLevelDefault()
```
    Sets the case level mode to the initial mode set during construction of the RuleBasedCollator. See setCaseLevel(boolean) for more details.
    
    See Also:
    
    setCaseLevel(boolean), isCaseLevel()
    
    Status:
    Stable ICU 2.8.
  - setDecompositionDefault
```
public void setDecompositionDefault()
```
    Sets the decomposition mode to the initial mode set during construction of the RuleBasedCollator. See setDecomposition(int) for more details.
    
    See Also:
    
    getDecomposition(), setDecomposition(int)
    
    Status:
    Stable ICU 2.8.
  - setFrenchCollationDefault
```
public void setFrenchCollationDefault()
```
    Sets the French collation mode to the initial mode set during construction of the RuleBasedCollator. See setFrenchCollation(boolean) for more details.
    
    See Also:
    
    isFrenchCollation(), setFrenchCollation(boolean)
    
    Status:
    Stable ICU 2.8.
  - setStrengthDefault
```
public void setStrengthDefault()
```
    Sets the collation strength to the initial mode set during the construction of the RuleBasedCollator. See setStrength(int) for more details.
    
    See Also:
    
    setStrength(int), getStrength()
    
    Status:
    Stable ICU 2.8.
  - setNumericCollationDefault
```
public void setNumericCollationDefault()
```
    Method to set numeric collation to its default value.
    
    See Also:
    
    getNumericCollation(), setNumericCollation(boolean)
    
    Status:
    Stable ICU 2.8.
  - setFrenchCollation
```
public void setFrenchCollation(boolean flag)
```
    Sets the mode for the direction of SECONDARY weights to be used in French collation. If set to false, which treats SECONDARY weights in the order they appear. If set to true, the SECONDARY weights will be sorted backwards. See the section on French collation for more information. The default setting in a Collator object depends on the locale data loaded from the resources. For example, for "fr_CA" locale, the default is true.
    
    Parameters:
    
    flag - true to set the French collation on, false to set it off
    
    See Also:
    
    isFrenchCollation(), setFrenchCollationDefault()
    
    Status:
    Stable ICU 2.8.
  - setAlternateHandlingShifted
```
public void setAlternateHandlingShifted(boolean shifted)
```
    Sets the alternate handling for QUATERNARY strength to be either shifted or non-ignorable. See the UCA definition on Variable Weighting. This attribute will only be effective when QUATERNARY strength is set. If the mode is set to false, it corresponds to the NON_IGNORABLE mode in UCA. In the NON_IGNORABLE mode, the RuleBasedCollator treats all the code points with non-ignorable primary weights in the same way. If the mode is set to true, the behavior corresponds to SHIFTED defined in UCA, this causes code points with PRIMARY orders that are equal or below the variable top value to be ignored in PRIMARY order and moved to the QUATERNARY order. The default setting in a Collator object depends on the locale data loaded from the resources. For most locales, the default is false, but for others, such as "th", the default could be true.
    
    Parameters:
    
    shifted - true if SHIFTED behavior for alternate handling is desired, false for the NON_IGNORABLE behavior.
    
    See Also:
    
    isAlternateHandlingShifted(), setAlternateHandlingDefault()
    
    Status:
    Stable ICU 2.8.
  - setCaseLevel
```
public void setCaseLevel(boolean flag)
```
    When case level is set to true, an additional weight is formed between the SECONDARY and TERTIARY weight, known as the case level. The case level is used to distinguish large and small Japanese Kana characters. Case level could also be used in other situations. For example to distinguish certain Pinyin characters. If the value is false, it means the case level is not generated. The contents of the case level are affected by the case first mode. A simple way to ignore accent differences in a string is to set the strength to PRIMARY and enable case level. The default setting in a Collator object depends on the locale data loaded from the resources.
    See the section on case level for more information.
    
    Parameters:
    
    flag - true if case level sorting is required, false otherwise
    
    See Also:
    
    setCaseLevelDefault(), isCaseLevel()
    
    Status:
    Stable ICU 2.8.
  - setDecomposition
```
public void setDecomposition(int decomposition)
```
    Sets the decomposition mode of this Collator. Setting this decomposition attribute with CANONICAL_DECOMPOSITION allows the Collator to handle un-normalized text properly, producing the same results as if the text were normalized. If NO_DECOMPOSITION is set, it is the user's responsibility to insure that all text is already in the appropriate form before a comparison or before getting a CollationKey. Adjusting decomposition mode allows the user to select between faster and more complete collation behavior.
    Since a great many of the world's languages do not require text normalization, most locales set NO_DECOMPOSITION as the default decomposition mode. The default decompositon mode for the Collator is NO_DECOMPOSITON, unless specified otherwise by the locale used to create the Collator.
    See getDecomposition for a description of decomposition mode.
    
    Overrides:
    
    setDecomposition in class Collator
    
    Parameters:
    
    decomposition - the new decomposition mode
    
    Throws:
    
    IllegalArgumentException - If the given value is not a valid decomposition mode.
    
    See Also:
    
    getDecomposition(), Collator.NO_DECOMPOSITION, Collator.CANONICAL_DECOMPOSITION
    
    Status:
    Stable ICU 2.8.
  - setStrength
```
public void setStrength(int newStrength)
```
    Sets this Collator's strength attribute. The strength attribute determines the minimum level of difference considered significant during comparison.
    See the Collator class description for an example of use.
    
    Overrides:
    
    setStrength in class Collator
    
    Parameters:
    
    newStrength - the new strength value.
    
    Throws:
    
    IllegalArgumentException - If the new strength value is not one of PRIMARY, SECONDARY, TERTIARY, QUATERNARY or IDENTICAL.
    
    See Also:
    
    getStrength(), setStrengthDefault(), Collator.PRIMARY, Collator.SECONDARY, Collator.TERTIARY, Collator.QUATERNARY, Collator.IDENTICAL
    
    Status:
    Stable ICU 2.8.
  - setMaxVariable
```
public RuleBasedCollator setMaxVariable(int group)
```
    [icu] Sets the variable top to the top of the specified reordering group. The variable top determines the highest-sorting character which is affected by the alternate handling behavior. If that attribute is set to NON_IGNORABLE, then the variable top has no effect.
    
    Overrides:
    
    setMaxVariable in class Collator
    
    Parameters:
    
    group - one of Collator.ReorderCodes.SPACE, Collator.ReorderCodes.PUNCTUATION, Collator.ReorderCodes.SYMBOL, Collator.ReorderCodes.CURRENCY; or Collator.ReorderCodes.DEFAULT to restore the default max variable group
    
    Returns:
    
    this
    
    See Also:
    
    getMaxVariable()
    
    Status:
    Stable ICU 53.
  - getMaxVariable
```
public int getMaxVariable()
```
    [icu] Returns the maximum reordering group whose characters are affected by the alternate handling behavior.
    
    Overrides:
    
    getMaxVariable in class Collator
    
    Returns:
    
    the maximum variable reordering group.
    
    See Also:
    
    setMaxVariable(int)
    
    Status:
    Stable ICU 53.
  - setVariableTop
```
@Deprecated
public int setVariableTop(String varTop)
```
    Deprecated. ICU 53 Call setMaxVariable(int) instead.
    
    [icu] Sets the variable top to the primary weight of the specified string.
    Beginning with ICU 53, the variable top is pinned to the top of one of the supported reordering groups, and it must not be beyond the last of those groups. See setMaxVariable(int).
    Specified by:
    
    setVariableTop in class Collator
    
    Parameters:
    
    varTop - one or more (if contraction) characters to which the variable top should be set
    
    Returns:
    
    variable top primary weight
    
    Throws:
    IllegalArgumentException - is thrown if varTop argument is not a valid variable top element. A variable top element is invalid when
    
    it is a contraction that does not exist in the Collation order
    the variable top is beyond the last reordering group supported by setMaxVariable()
    when the varTop argument is null or zero in length.
    See Also:
    
    getVariableTop(), setAlternateHandlingShifted(boolean)
  - setVariableTop
```
@Deprecated
public void setVariableTop(int varTop)
```
    Deprecated. ICU 53 Call setMaxVariable() instead.
    
    [icu] Sets the variable top to the specified primary weight.
    Beginning with ICU 53, the variable top is pinned to the top of one of the supported reordering groups, and it must not be beyond the last of those groups. See setMaxVariable(int).
    
    Specified by:
    
    setVariableTop in class Collator
    
    Parameters:
    
    varTop - primary weight, as returned by setVariableTop or getVariableTop
    
    See Also:
    
    getVariableTop(), setVariableTop(String)
  - setNumericCollation
```
public void setNumericCollation(boolean flag)
```
    [icu] When numeric collation is turned on, this Collator makes substrings of digits sort according to their numeric values.
    This is a way to get '100' to sort AFTER '2'. Note that the longest digit substring that can be treated as a single unit is 254 digits (not counting leading zeros). If a digit substring is longer than that, the digits beyond the limit will be treated as a separate digit substring.
    A "digit" in this sense is a code point with General_Category=Nd, which does not include circled numbers, roman numerals, etc. Only a contiguous digit substring is considered, that is, non-negative integers without separators. There is no support for plus/minus signs, decimals, exponents, etc.
    
    Parameters:
    
    flag - true to turn numeric collation on and false to turn it off
    
    See Also:
    
    getNumericCollation(), setNumericCollationDefault()
    
    Status:
    Stable ICU 2.8.
  - setReorderCodes
```
public void setReorderCodes(int... order)
```
    Sets the reordering codes for this collator. Collation reordering allows scripts and some other groups of characters to be moved relative to each other. This reordering is done on top of the DUCET/CLDR standard collation order. Reordering can specify groups to be placed at the start and/or the end of the collation order. These groups are specified using UScript codes and Collator.ReorderCodes entries.
    By default, reordering codes specified for the start of the order are placed in the order given after several special non-script blocks. These special groups of characters are space, punctuation, symbol, currency, and digit. These special groups are represented with Collator.ReorderCodes entries. Script groups can be intermingled with these special non-script groups if those special groups are explicitly specified in the reordering.
    The special code OTHERS stands for any script that is not explicitly mentioned in the list of reordering codes given. Anything that is after OTHERS will go at the very end of the reordering in the order given.
    The special reorder code DEFAULT will reset the reordering for this collator to the default for this collator. The default reordering may be the DUCET/CLDR order or may be a reordering that was specified when this collator was created from resource data or from rules. The DEFAULT code must be the sole code supplied when it is used. If not, then an IllegalArgumentException will be thrown.
    The special reorder code NONE will remove any reordering for this collator. The result of setting no reordering will be to have the DUCET/CLDR ordering used. The NONE code must be the sole code supplied when it is used.
    
    Overrides:
    
    setReorderCodes in class Collator
    
    Parameters:
    
    order - the reordering codes to apply to this collator; if this is null or an empty array then this clears any existing reordering
    
    Throws:
    
    IllegalArgumentException - if the reordering codes are malformed in any way (e.g. duplicates, multiple reset codes, overlapping equivalent scripts)
    
    See Also:
    
    getReorderCodes(), Collator.getEquivalentReorderCodes(int), Collator.ReorderCodes, UScript
    
    Status:
    Stable ICU 4.8.
  - getRules
```
public String getRules()
```
    Gets the collation tailoring rules for this RuleBasedCollator. Equivalent to String getRules(false).
    
    Returns:
    
    the collation tailoring rules
    
    See Also:
    
    getRules(boolean)
    
    Status:
    Stable ICU 2.8.
  - getRules
```
public String getRules(boolean fullrules)
```
    Returns current rules. The argument defines whether full rules (root collation + tailored) rules are returned or just the tailoring.
    The root collation rules are an approximation of the root collator's sort order. They are almost never used or useful at runtime and can be removed from the data. See User Guide: Collation Customization, Building on Existing Locales
    getRules() should normally be used instead.
    
    Parameters:
    
    fullrules - true if the rules that defines the full set of collation order is required, otherwise false for returning only the tailored rules
    
    Returns:
    
    the current rules that defines this Collator.
    
    See Also:
    
    getRules()
    
    Status:
    Stable ICU 2.6.
  - getTailoredSet
```
public UnicodeSet getTailoredSet()
```
    Get a UnicodeSet that contains all the characters and sequences tailored in this collator.
    
    Overrides:
    
    getTailoredSet in class Collator
    
    Returns:
    
    a pointer to a UnicodeSet object containing all the code points and sequences that may sort differently than in the root collator.
    
    Status:
    Stable ICU 2.4.
  - getContractionsAndExpansions
```
public void getContractionsAndExpansions(UnicodeSet contractions,
                                         UnicodeSet expansions,
                                         boolean addPrefixes)
                                  throws Exception
```
    Gets unicode sets containing contractions and/or expansions of a collator
    
    Parameters:
    
    contractions - if not null, set to contain contractions
    
    expansions - if not null, set to contain expansions
    
    addPrefixes - add the prefix contextual elements to contractions
    
    Throws:
    
    Exception - Throws an exception if any errors occurs.
    
    Status:
    Stable ICU 3.4.
  - getCollationKey
```
public CollationKey getCollationKey(String source)
```
    Get a Collation key for the argument String source from this RuleBasedCollator.
    General recommendation:
    If comparison are to be done to the same String multiple times, it would be more efficient to generate CollationKeys for the Strings and use CollationKey.compareTo(CollationKey) for the comparisons. If the each Strings are compared to only once, using the method RuleBasedCollator.compare(String, String) will have a better performance.
    See the class documentation for an explanation about CollationKeys.
    
    Specified by:
    
    getCollationKey in class Collator
    
    Parameters:
    
    source - the text String to be transformed into a collation key.
    
    Returns:
    
    the CollationKey for the given String based on this RuleBasedCollator's collation rules. If the source String is null, a null CollationKey is returned.
    
    See Also:
    
    CollationKey, compare(String, String), getRawCollationKey(java.lang.String, com.ibm.icu.text.RawCollationKey)
    
    Status:
    Stable ICU 2.8.
  - getRawCollationKey
```
public RawCollationKey getRawCollationKey(String source,
                                          RawCollationKey key)
```
    Gets the simpler form of a CollationKey for the String source following the rules of this Collator and stores the result into the user provided argument key. If key has a internal byte array of length that's too small for the result, the internal byte array will be grown to the exact required size.
    
    Specified by:
    
    getRawCollationKey in class Collator
    
    Parameters:
    
    source - the text String to be transformed into a RawCollationKey
    
    key - output RawCollationKey to store results
    
    Returns:
    
    If key is null, a new instance of RawCollationKey will be created and returned, otherwise the user provided key will be returned.
    
    See Also:
    
    getCollationKey(java.lang.String), compare(String, String), RawCollationKey
    
    Status:
    Stable ICU 2.8.
  - internalGetCEs
```
@Deprecated
public long[] internalGetCEs(CharSequence str)
```
    Deprecated. This API is ICU internal only.
    
    Returns the CEs for the string.
    
    Parameters:
    
    str - the string
    
    Status:
    Internal. This API is ICU internal only.
  - getStrength
```
public int getStrength()
```
    Returns this Collator's strength attribute. The strength attribute determines the minimum level of difference considered significant.
    [icu] Note: This can return QUATERNARY strength, which is not supported by the JDK version.
    See the Collator class description for more details.
    
    Overrides:
    
    getStrength in class Collator
    
    Returns:
    
    this Collator's current strength attribute.
    
    See Also:
    
    setStrength(int), Collator.PRIMARY, Collator.SECONDARY, Collator.TERTIARY, Collator.QUATERNARY, Collator.IDENTICAL
    
    Status:
    Stable ICU 2.8.
  - getDecomposition
```
public int getDecomposition()
```
    Returns the decomposition mode of this Collator. The decomposition mode determines how Unicode composed characters are handled.
    See the Collator class description for more details.
    
    Overrides:
    
    getDecomposition in class Collator
    
    Returns:
    
    the decomposition mode
    
    See Also:
    
    setDecomposition(int), Collator.NO_DECOMPOSITION, Collator.CANONICAL_DECOMPOSITION
    
    Status:
    Stable ICU 2.8.
  - isUpperCaseFirst
```
public boolean isUpperCaseFirst()
```
    Return true if an uppercase character is sorted before the corresponding lowercase character. See setCaseFirst(boolean) for details.
    
    Returns:
    
    true if upper cased characters are sorted before lower cased characters, false otherwise
    
    See Also:
    
    setUpperCaseFirst(boolean), setLowerCaseFirst(boolean), isLowerCaseFirst(), setCaseFirstDefault()
    
    Status:
    Stable ICU 2.8.
  - isLowerCaseFirst
```
public boolean isLowerCaseFirst()
```
    Return true if a lowercase character is sorted before the corresponding uppercase character. See setCaseFirst(boolean) for details.
    
    Returns:
    
    true lower cased characters are sorted before upper cased characters, false otherwise
    
    See Also:
    
    setUpperCaseFirst(boolean), setLowerCaseFirst(boolean), isUpperCaseFirst(), setCaseFirstDefault()
    
    Status:
    Stable ICU 2.8.
  - isAlternateHandlingShifted
```
public boolean isAlternateHandlingShifted()
```
    Checks if the alternate handling behavior is the UCA defined SHIFTED or NON_IGNORABLE. If return value is true, then the alternate handling attribute for the Collator is SHIFTED. Otherwise if return value is false, then the alternate handling attribute for the Collator is NON_IGNORABLE See setAlternateHandlingShifted(boolean) for more details.
    
    Returns:
    
    true or false
    
    See Also:
    
    setAlternateHandlingShifted(boolean), setAlternateHandlingDefault()
    
    Status:
    Stable ICU 2.8.
  - isCaseLevel
```
public boolean isCaseLevel()
```
    Checks if case level is set to true. See setCaseLevel(boolean) for details.
    
    Returns:
    
    the case level mode
    
    See Also:
    
    setCaseLevelDefault(), isCaseLevel(), setCaseLevel(boolean)
    
    Status:
    Stable ICU 2.8.
  - isFrenchCollation
```
public boolean isFrenchCollation()
```
    Checks if French Collation is set to true. See setFrenchCollation(boolean) for details.
    
    Returns:
    
    true if French Collation is set to true, false otherwise
    
    See Also:
    
    setFrenchCollation(boolean), setFrenchCollationDefault()
    
    Status:
    Stable ICU 2.8.
  - isHiraganaQuaternary
```
@Deprecated
public boolean isHiraganaQuaternary()
```
    Deprecated. ICU 50 Implementation detail, cannot be set via API, was removed from implementation.
    
    Checks if the Hiragana Quaternary mode is set on. See setHiraganaQuaternary(boolean) for more details.
    This attribute was an implementation detail of the CLDR Japanese tailoring. Since ICU 50, this attribute is not settable any more via API functions. Since CLDR 25/ICU 53, explicit quaternary relations are used to achieve the same Japanese sort order.
    
    Returns:
    
    false
    
    See Also:
    
    setHiraganaQuaternaryDefault(), setHiraganaQuaternary(boolean)
  - getVariableTop
```
public int getVariableTop()
```
    [icu] Gets the variable top value of a Collator.
    
    Specified by:
    
    getVariableTop in class Collator
    
    Returns:
    
    the variable top primary weight
    
    See Also:
    
    getMaxVariable()
    
    Status:
    Stable ICU 2.6.
  - getNumericCollation
```
public boolean getNumericCollation()
```
    Method to retrieve the numeric collation value. When numeric collation is turned on, this Collator generates a collation key for the numeric value of substrings of digits. This is a way to get '100' to sort AFTER '2'
    
    Returns:
    
    true if numeric collation is turned on, false otherwise
    
    See Also:
    
    setNumericCollation(boolean), setNumericCollationDefault()
    
    Status:
    Stable ICU 2.8.
  - getReorderCodes
```
public int[] getReorderCodes()
```
    Retrieves the reordering codes for this collator. These reordering codes are a combination of UScript codes and ReorderCodes.
    
    Overrides:
    
    getReorderCodes in class Collator
    
    Returns:
    
    a copy of the reordering codes for this collator; if none are set then returns an empty array
    
    See Also:
    
    setReorderCodes(int...), Collator.getEquivalentReorderCodes(int)
    
    Status:
    Stable ICU 4.8.
  - equals
```
public boolean equals(Object obj)
```
    Compares the equality of two Collator objects. Collator objects are equal if they have the same collation (sorting & searching) behavior.
    The base class checks for null and for equal types. Subclasses should override.
    
    Specified by:
    
    equals in interface Comparator<Object>
    
    Overrides:
    
    equals in class Collator
    
    Parameters:
    
    obj - the Collator to compare to.
    
    Returns:
    
    true if this Collator has exactly the same collation behavior as obj, false otherwise.
    
    Status:
    Stable ICU 2.8.
  - hashCode
```
public int hashCode()
```
    Generates a unique hash code for this RuleBasedCollator.
    
    Overrides:
    
    hashCode in class Collator
    
    Returns:
    
    the unique hash code for this Collator
    
    Status:
    Stable ICU 2.8.
  - compare
```
public int compare(String source,
                   String target)
```
    Compares the source text String to the target text String according to the collation rules, strength and decomposition mode for this RuleBasedCollator. Returns an integer less than, equal to or greater than zero depending on whether the source String is less than, equal to or greater than the target String. See the Collator class description for an example of use.
    General recommendation:
    If comparison are to be done to the same String multiple times, it would be more efficient to generate CollationKeys for the Strings and use CollationKey.compareTo(CollationKey) for the comparisons. If speed performance is critical and object instantiation is to be reduced, further optimization may be achieved by generating a simpler key of the form RawCollationKey and reusing this RawCollationKey object with the method RuleBasedCollator.getRawCollationKey. Internal byte representation can be directly accessed via RawCollationKey and stored for future use. Like CollationKey, RawCollationKey provides a method RawCollationKey.compareTo for key comparisons. If the each Strings are compared to only once, using the method RuleBasedCollator.compare(String, String) will have a better performance.
    
    Specified by:
    
    compare in class Collator
    
    Parameters:
    
    source - the source text String.
    
    target - the target text String.
    
    Returns:
    
    Returns an integer value. Value is less than zero if source is less than target, value is zero if source and target are equal, value is greater than zero if source is greater than target.
    
    See Also:
    
    CollationKey, getCollationKey(java.lang.String)
    
    Status:
    Stable ICU 2.8.
  - doCompare
```
@Deprecated
protected int doCompare(CharSequence left,
                                    CharSequence right)
```
    Deprecated. This API is ICU internal only.
    
    Compares two CharSequences.
    
    Overrides:
    
    doCompare in class Collator
    
    Status:
    Internal. This API is ICU internal only.
  - getVersion
```
public VersionInfo getVersion()
```
    Get the version of this collator object.
    
    Specified by:
    
    getVersion in class Collator
    
    Returns:
    
    the version object associated with this collator
    
    Status:
    Stable ICU 2.8.
  - getUCAVersion
```
public VersionInfo getUCAVersion()
```
    Get the UCA version of this collator object.
    
    Specified by:
    
    getUCAVersion in class Collator
    
    Returns:
    
    the version object associated with this collator
    
    Status:
    Stable ICU 2.8.
  - getLocale
```
public ULocale getLocale(ULocale.Type type)
```
    [icu] Returns the locale that was used to create this object, or null. This may may differ from the locale requested at the time of this object's creation. For example, if an object is created for locale en_US_CALIFORNIA, the actual data may be drawn from en (the actual locale), and en_US may be the most specific locale that exists (the valid locale).
    Note: This method will be implemented in ICU 3.0; ICU 2.8 contains a partial preview implementation. The actual locale is returned correctly, but the valid locale is not, in most cases.
    The base class method always returns ULocale.ROOT. Subclasses should override it if appropriate.
    
    Overrides:
    
    getLocale in class Collator
    
    Parameters:
    
    type - type of information requested, either ULocale.VALID_LOCALE or ULocale.ACTUAL_LOCALE.
    
    Returns:
    
    the information specified by type, or null if this object was not constructed from locale data.
    
    See Also:
    
    ULocale, ULocale.VALID_LOCALE, ULocale.ACTUAL_LOCALE
    
    Status:
    Draft ICU 53 (retain).

Class RuleBasedCollator

Nested Class Summary

Nested classes/interfaces inherited from class com.ibm.icu.text.Collator

Field Summary

Fields inherited from class com.ibm.icu.text.Collator

Constructor Summary

Method Summary

Methods inherited from class com.ibm.icu.text.Collator

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Comparator

Constructor Detail

RuleBasedCollator

Method Detail

clone

getCollationElementIterator

getCollationElementIterator

getCollationElementIterator

isFrozen

freeze

cloneAsThawed

setHiraganaQuaternary

setHiraganaQuaternaryDefault

setUpperCaseFirst

setLowerCaseFirst

setCaseFirstDefault

setAlternateHandlingDefault

setCaseLevelDefault

setDecompositionDefault

setFrenchCollationDefault

setStrengthDefault

setNumericCollationDefault

setFrenchCollation

setAlternateHandlingShifted

setCaseLevel

setDecomposition

setStrength

setMaxVariable

getMaxVariable

setVariableTop

setVariableTop

setNumericCollation

setReorderCodes

getRules

getRules

getTailoredSet

getContractionsAndExpansions

getCollationKey

getRawCollationKey

internalGetCEs

getStrength

getDecomposition

isUpperCaseFirst

isLowerCaseFirst

isAlternateHandlingShifted

isCaseLevel

isFrenchCollation

isHiraganaQuaternary

getVariableTop

getNumericCollation

getReorderCodes

equals

hashCode

compare

doCompare

getVersion

getUCAVersion

getLocale