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RuleBasedCollator

public final class RuleBasedCollator
extends Collator

java.lang.Object
   ↳ android.icu.text.Collator
     ↳ android.icu.text.RuleBasedCollator


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

Summary

Inherited constants

Public constructors

RuleBasedCollator(String rules)

Constructor that takes the argument rules for customization.

Public methods

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.

boolean equals(Object obj)

Compares the equality of two Collator objects.

Collator freeze()

Freezes the collator.

CollationElementIterator getCollationElementIterator(UCharacterIterator source)

Return a CollationElementIterator for the given UCharacterIterator.

CollationElementIterator getCollationElementIterator(String source)

Return a CollationElementIterator for the given String.

CollationElementIterator getCollationElementIterator(CharacterIterator source)

Return a CollationElementIterator for the given CharacterIterator.

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.

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.

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.

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 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 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.

Inherited methods

Public constructors

RuleBasedCollator

added in API level 24
public RuleBasedCollator (String rules)

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 String: 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

Public methods

clone

added in API level 24
public Object clone ()

Clones the RuleBasedCollator

Returns
Object a new instance of this RuleBasedCollator object

Throws
CloneNotSupportedException

cloneAsThawed

added in API level 24
public RuleBasedCollator cloneAsThawed ()

Provides for the clone operation. Any clone is initially unfrozen.

Returns
RuleBasedCollator

compare

added in API level 24
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.

Parameters
source String: the source text String.

target String: the target text String.

Returns
int 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.

equals

added in API level 24
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.

Parameters
obj Object: the Collator to compare to.

Returns
boolean true if this Collator has exactly the same collation behavior as obj, false otherwise.

freeze

added in API level 24
public Collator freeze ()

Freezes the collator.

Returns
Collator the collator itself.

getCollationElementIterator

added in API level 24
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.

Parameters
source UCharacterIterator

Returns
CollationElementIterator

getCollationElementIterator

added in API level 24
public CollationElementIterator getCollationElementIterator (String source)

Return a CollationElementIterator for the given String.

Parameters
source String

Returns
CollationElementIterator

getCollationElementIterator

added in API level 24
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.

Parameters
source CharacterIterator

Returns
CollationElementIterator

getCollationKey

added in API level 24
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.

Parameters
source String: the text String to be transformed into a collation key.

Returns
CollationKey the CollationKey for the given String based on this RuleBasedCollator's collation rules. If the source String is null, a null CollationKey is returned.

getContractionsAndExpansions

added in API level 24
public void getContractionsAndExpansions (UnicodeSet contractions, 
                UnicodeSet expansions, 
                boolean addPrefixes)

Gets unicode sets containing contractions and/or expansions of a collator

Parameters
contractions UnicodeSet: if not null, set to contain contractions

expansions UnicodeSet: if not null, set to contain expansions

addPrefixes boolean: add the prefix contextual elements to contractions

Throws
Exception Throws an exception if any errors occurs.

getDecomposition

added in API level 24
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.

Returns
int the decomposition mode

getMaxVariable

added in API level 24
public int getMaxVariable ()

[icu] Returns the maximum reordering group whose characters are affected by the alternate handling behavior.

Returns
int the maximum variable reordering group.

getNumericCollation

added in API level 24
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
boolean true if numeric collation is turned on, false otherwise

getReorderCodes

added in API level 24
public int[] getReorderCodes ()

Retrieves the reordering codes for this collator. These reordering codes are a combination of UScript codes and ReorderCodes.

Returns
int[] a copy of the reordering codes for this collator; if none are set then returns an empty array

getRules

added in API level 24
public String getRules ()

Gets the collation tailoring rules for this RuleBasedCollator. Equivalent to String getRules(false).

On Android, the returned string will be empty unless this instance was constructed using RuleBasedCollator(String).

Returns
String the collation tailoring rules

See also:

getRules

added in API level 24
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 boolean: true if the rules that defines the full set of collation order is required, otherwise false for returning only the tailored rules

Returns
String the current rules that defines this Collator.

See also:

getStrength

added in API level 24
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.

Returns
int this Collator's current strength attribute.

getTailoredSet

added in API level 24
public UnicodeSet getTailoredSet ()

Get a UnicodeSet that contains all the characters and sequences tailored in this collator.

Returns
UnicodeSet a pointer to a UnicodeSet object containing all the code points and sequences that may sort differently than in the root collator.

getUCAVersion

added in API level 24
public VersionInfo getUCAVersion ()

Get the UCA version of this collator object.

Returns
VersionInfo the version object associated with this collator

getVariableTop

added in API level 24
public int getVariableTop ()

[icu] Gets the variable top value of a Collator.

Returns
int the variable top primary weight

See also:

getVersion

added in API level 24
public VersionInfo getVersion ()

Get the version of this collator object.

Returns
VersionInfo the version object associated with this collator

hashCode

added in API level 24
public int hashCode ()

Generates a unique hash code for this RuleBasedCollator.

Returns
int the unique hash code for this Collator

isAlternateHandlingShifted

added in API level 24
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
boolean true or false

isCaseLevel

added in API level 24
public boolean isCaseLevel ()

Checks if case level is set to true. See setCaseLevel(boolean) for details.

Returns
boolean the case level mode

isFrenchCollation

added in API level 24
public boolean isFrenchCollation ()

Checks if French Collation is set to true. See setFrenchCollation(boolean) for details.

Returns
boolean true if French Collation is set to true, false otherwise

isFrozen

added in API level 24
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.

Returns
boolean

isLowerCaseFirst

added in API level 24
public boolean isLowerCaseFirst ()

Return true if a lowercase character is sorted before the corresponding uppercase character. See setCaseFirst(boolean) for details.

Returns
boolean true lower cased characters are sorted before upper cased characters, false otherwise

isUpperCaseFirst

added in API level 24
public boolean isUpperCaseFirst ()

Return true if an uppercase character is sorted before the corresponding lowercase character. See setCaseFirst(boolean) for details.

Returns
boolean true if upper cased characters are sorted before lower cased characters, false otherwise

setAlternateHandlingDefault

added in API level 24
public void setAlternateHandlingDefault ()

Sets the alternate handling mode to the initial mode set during construction of the RuleBasedCollator. See setAlternateHandling(boolean) for more details.

setAlternateHandlingShifted

added in API level 24
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. The default value for this mode is false, corresponding 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.

Parameters
shifted boolean: true if SHIFTED behavior for alternate handling is desired, false for the NON_IGNORABLE behavior.

setCaseFirstDefault

added in API level 24
public 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.

setCaseLevel

added in API level 24
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. The default value is false, which 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.

See the section on case level for more information.

Parameters
flag boolean: true if case level sorting is required, false otherwise

setCaseLevelDefault

added in API level 24
public void setCaseLevelDefault ()

Sets the case level mode to the initial mode set during construction of the RuleBasedCollator. See setCaseLevel(boolean) for more details.

setDecomposition

added in API level 24
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.

Parameters
decomposition int: the new decomposition mode

Throws
IllegalArgumentException If the given value is not a valid decomposition mode.

setDecompositionDefault

added in API level 24
public void setDecompositionDefault ()

Sets the decomposition mode to the initial mode set during construction of the RuleBasedCollator. See setDecomposition(int) for more details.

setFrenchCollation

added in API level 24
public void setFrenchCollation (boolean flag)

Sets the mode for the direction of SECONDARY weights to be used in French collation. The default value is 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.

Parameters
flag boolean: true to set the French collation on, false to set it off

setFrenchCollationDefault

added in API level 24
public void setFrenchCollationDefault ()

Sets the French collation mode to the initial mode set during construction of the RuleBasedCollator. See setFrenchCollation(boolean) for more details.

setLowerCaseFirst

added in API level 24
public void setLowerCaseFirst (boolean lowerfirst)

Sets the orders of lower cased characters to sort before upper cased characters, in strength TERTIARY. The default mode is false. 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.

Parameters
lowerfirst boolean: true for sorting lower cased characters before upper cased characters, false to ignore case preferences.

setMaxVariable

added in API level 24
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.

Parameters
group int: 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
RuleBasedCollator this

See also:

setNumericCollation

added in API level 24
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 boolean: true to turn numeric collation on and false to turn it off

setNumericCollationDefault

added in API level 24
public void setNumericCollationDefault ()

Method to set numeric collation to its default value.

setReorderCodes

added in API level 24
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.

Parameters
order int: 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)

setStrength

added in API level 24
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.

Parameters
newStrength int: the new strength value.

Throws
IllegalArgumentException If the new strength value is not one of PRIMARY, SECONDARY, TERTIARY, QUATERNARY or IDENTICAL.

setStrengthDefault

added in API level 24
public void setStrengthDefault ()

Sets the collation strength to the initial mode set during the construction of the RuleBasedCollator. See setStrength(int) for more details.

setUpperCaseFirst

added in API level 24
public void setUpperCaseFirst (boolean upperfirst)

Sets whether uppercase characters sort before lowercase characters or vice versa, in strength TERTIARY. The default mode is false, and so lowercase characters sort before uppercase characters. If true, sort upper case characters first.

Parameters
upperfirst boolean: true to sort uppercase characters before lowercase characters, false to sort lowercase characters before uppercase characters