The Collator class performs locale-sensitive String comparison. You use this class to build searching and sorting routines for natural language text.
Collator is an abstract base class. Subclasses implement specific collation strategies. One subclass, RuleBasedCollator, is currently provided with the Java Platform and is applicable to a wide set of languages. Other subclasses may be created to handle more specialized needs.
Like other locale-sensitive classes, you can use the static factory method, getInstance, to obtain the appropriate Collator object for a given locale. You will only need to look at the subclasses of Collator if you need to understand the details of a particular collation strategy or if you need to modify that strategy.
The following example shows how to compare two strings using the Collator for the default locale.
// Compare two strings in the default locale Collator myCollator = Collator.getInstance(); if( myCollator.compare("abc", "ABC") < 0 ) System.out.println("abc is less than ABC"); else System.out.println("abc is greater than or equal to ABC");
You can set a Collator's strength property to determine the level of difference considered significant in comparisons. Four strengths are provided: PRIMARY, SECONDARY, TERTIARY, and IDENTICAL. The exact assignment of strengths to language features is locale dependant. For example, in Czech, "e" and "f" are considered primary differences, while "e" and "ě" are secondary differences, "e" and "E" are tertiary differences and "e" and "e" are identical. The following shows how both case and accents could be ignored for US English.
//Get the Collator for US English and set its strength to PRIMARY Collator usCollator = Collator.getInstance(Locale.US); usCollator.setStrength(Collator.PRIMARY); if( usCollator.compare("abc", "ABC") == 0 ) { System.out.println("Strings are equivalent"); }
For comparing Strings exactly once, the compare method provides the best performance. When sorting a list of Strings however, it is generally necessary to compare each String multiple times. In this case, CollationKeys provide better performance. The CollationKey class converts a String to a series of bits that can be compared bitwise against other CollationKeys. A CollationKey is created by a Collator object for a given String.
Note: CollationKeys from different Collators can not be compared. See the class description for CollationKey for an example using CollationKeys.
The Collator class performs locale-sensitive String comparison. You use this class to build searching and sorting routines for natural language text. Collator is an abstract base class. Subclasses implement specific collation strategies. One subclass, RuleBasedCollator, is currently provided with the Java Platform and is applicable to a wide set of languages. Other subclasses may be created to handle more specialized needs. Like other locale-sensitive classes, you can use the static factory method, getInstance, to obtain the appropriate Collator object for a given locale. You will only need to look at the subclasses of Collator if you need to understand the details of a particular collation strategy or if you need to modify that strategy. The following example shows how to compare two strings using the Collator for the default locale. // Compare two strings in the default locale Collator myCollator = Collator.getInstance(); if( myCollator.compare("abc", "ABC") < 0 ) System.out.println("abc is less than ABC"); else System.out.println("abc is greater than or equal to ABC"); You can set a Collator's strength property to determine the level of difference considered significant in comparisons. Four strengths are provided: PRIMARY, SECONDARY, TERTIARY, and IDENTICAL. The exact assignment of strengths to language features is locale dependant. For example, in Czech, "e" and "f" are considered primary differences, while "e" and "ě" are secondary differences, "e" and "E" are tertiary differences and "e" and "e" are identical. The following shows how both case and accents could be ignored for US English. //Get the Collator for US English and set its strength to PRIMARY Collator usCollator = Collator.getInstance(Locale.US); usCollator.setStrength(Collator.PRIMARY); if( usCollator.compare("abc", "ABC") == 0 ) { System.out.println("Strings are equivalent"); } For comparing Strings exactly once, the compare method provides the best performance. When sorting a list of Strings however, it is generally necessary to compare each String multiple times. In this case, CollationKeys provide better performance. The CollationKey class converts a String to a series of bits that can be compared bitwise against other CollationKeys. A CollationKey is created by a Collator object for a given String. Note: CollationKeys from different Collators can not be compared. See the class description for CollationKey for an example using CollationKeys.
Static Constant.
Decomposition mode value. With CANONICAL_DECOMPOSITION set, characters that are canonical variants according to Unicode standard will be decomposed for collation. This should be used to get correct collation of accented characters.
CANONICAL_DECOMPOSITION corresponds to Normalization Form D as described in Unicode Technical Report #15.
type: int
Static Constant. Decomposition mode value. With CANONICAL_DECOMPOSITION set, characters that are canonical variants according to Unicode standard will be decomposed for collation. This should be used to get correct collation of accented characters. CANONICAL_DECOMPOSITION corresponds to Normalization Form D as described in Unicode Technical Report #15. type: int
Static Constant.
Decomposition mode value. With FULL_DECOMPOSITION set, both Unicode canonical variants and Unicode compatibility variants will be decomposed for collation. This causes not only accented characters to be collated, but also characters that have special formats to be collated with their norminal form. For example, the half-width and full-width ASCII and Katakana characters are then collated together. FULL_DECOMPOSITION is the most complete and therefore the slowest decomposition mode.
FULL_DECOMPOSITION corresponds to Normalization Form KD as described in Unicode Technical Report #15.
type: int
Static Constant. Decomposition mode value. With FULL_DECOMPOSITION set, both Unicode canonical variants and Unicode compatibility variants will be decomposed for collation. This causes not only accented characters to be collated, but also characters that have special formats to be collated with their norminal form. For example, the half-width and full-width ASCII and Katakana characters are then collated together. FULL_DECOMPOSITION is the most complete and therefore the slowest decomposition mode. FULL_DECOMPOSITION corresponds to Normalization Form KD as described in Unicode Technical Report #15. type: int
Static Constant.
Collator strength value. When set, all differences are considered significant during comparison. The assignment of strengths to language features is locale dependant. A common example is for control characters ("\u0001" vs "\u0002") to be considered equal at the PRIMARY, SECONDARY, and TERTIARY levels but different at the IDENTICAL level. Additionally, differences between pre-composed accents such as "\u00C0" (A-grave) and combining accents such as "A\u0300" (A, combining-grave) will be considered significant at the IDENTICAL level if decomposition is set to NO_DECOMPOSITION.
type: int
Static Constant. Collator strength value. When set, all differences are considered significant during comparison. The assignment of strengths to language features is locale dependant. A common example is for control characters ("\u0001" vs "\u0002") to be considered equal at the PRIMARY, SECONDARY, and TERTIARY levels but different at the IDENTICAL level. Additionally, differences between pre-composed accents such as "\u00C0" (A-grave) and combining accents such as "A\u0300" (A, combining-grave) will be considered significant at the IDENTICAL level if decomposition is set to NO_DECOMPOSITION. type: int
Static Constant.
Decomposition mode value. With NO_DECOMPOSITION set, accented characters will not be decomposed for collation. This is the default setting and provides the fastest collation but will only produce correct results for languages that do not use accents.
type: int
Static Constant. Decomposition mode value. With NO_DECOMPOSITION set, accented characters will not be decomposed for collation. This is the default setting and provides the fastest collation but will only produce correct results for languages that do not use accents. type: int
Static Constant.
Collator strength value. When set, only PRIMARY differences are considered significant during comparison. The assignment of strengths to language features is locale dependant. A common example is for different base letters ("a" vs "b") to be considered a PRIMARY difference.
type: int
Static Constant. Collator strength value. When set, only PRIMARY differences are considered significant during comparison. The assignment of strengths to language features is locale dependant. A common example is for different base letters ("a" vs "b") to be considered a PRIMARY difference. type: int
Static Constant.
Collator strength value. When set, only SECONDARY and above differences are considered significant during comparison. The assignment of strengths to language features is locale dependant. A common example is for different accented forms of the same base letter ("a" vs "�") to be considered a SECONDARY difference.
type: int
Static Constant. Collator strength value. When set, only SECONDARY and above differences are considered significant during comparison. The assignment of strengths to language features is locale dependant. A common example is for different accented forms of the same base letter ("a" vs "�") to be considered a SECONDARY difference. type: int
Static Constant.
Collator strength value. When set, only TERTIARY and above differences are considered significant during comparison. The assignment of strengths to language features is locale dependant. A common example is for case differences ("a" vs "A") to be considered a TERTIARY difference.
type: int
Static Constant. Collator strength value. When set, only TERTIARY and above differences are considered significant during comparison. The assignment of strengths to language features is locale dependant. A common example is for case differences ("a" vs "A") to be considered a TERTIARY difference. type: int
(*get-available-locales)
Returns an array of all locales for which the getInstance methods of this class can return localized instances. The returned array represents the union of locales supported by the Java runtime and by installed CollatorProvider implementations. It must contain at least a Locale instance equal to Locale.US.
returns: An array of locales for which localized
Collator instances are available. - java.util.Locale[]
Returns an array of all locales for which the getInstance methods of this class can return localized instances. The returned array represents the union of locales supported by the Java runtime and by installed CollatorProvider implementations. It must contain at least a Locale instance equal to Locale.US. returns: An array of locales for which localized Collator instances are available. - `java.util.Locale[]`
(*get-instance)
(*get-instance desired-locale)
Gets the Collator for the desired locale.
desired-locale - the desired locale. - java.util.Locale
returns: the Collator for the desired locale. - java.text.Collator
Gets the Collator for the desired locale. desired-locale - the desired locale. - `java.util.Locale` returns: the Collator for the desired locale. - `java.text.Collator`
(clone this)
Overrides Cloneable
returns: a clone of this instance. - java.lang.Object
Overrides Cloneable returns: a clone of this instance. - `java.lang.Object`
(compare this source target)
Compares the source string to the target string according to the collation rules for this Collator. 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.
For a one time comparison, this method has the best performance. If a given String will be involved in multiple comparisons, CollationKey.compareTo has the best performance. See the Collator class description for an example using CollationKeys.
source - the source string. - java.lang.String
target - the target string. - java.lang.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. - int
Compares the source string to the target string according to the collation rules for this Collator. 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. For a one time comparison, this method has the best performance. If a given String will be involved in multiple comparisons, CollationKey.compareTo has the best performance. See the Collator class description for an example using CollationKeys. source - the source string. - `java.lang.String` target - the target string. - `java.lang.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. - `int`
(equals this that)
(equals this source target)
Convenience method for comparing the equality of two strings based on this Collator's collation rules.
source - the source string to be compared with. - java.lang.String
target - the target string to be compared with. - java.lang.String
returns: true if the strings are equal according to the collation
rules. false, otherwise. - boolean
Convenience method for comparing the equality of two strings based on this Collator's collation rules. source - the source string to be compared with. - `java.lang.String` target - the target string to be compared with. - `java.lang.String` returns: true if the strings are equal according to the collation rules. false, otherwise. - `boolean`
(get-collation-key this source)
Transforms the String into a series of bits that can be compared bitwise to other CollationKeys. CollationKeys provide better performance than Collator.compare when Strings are involved in multiple comparisons. See the Collator class description for an example using CollationKeys.
source - the string to be transformed into a collation key. - java.lang.String
returns: the CollationKey for the given String based on this Collator's collation
rules. If the source String is null, a null CollationKey is returned. - java.text.CollationKey
Transforms the String into a series of bits that can be compared bitwise to other CollationKeys. CollationKeys provide better performance than Collator.compare when Strings are involved in multiple comparisons. See the Collator class description for an example using CollationKeys. source - the string to be transformed into a collation key. - `java.lang.String` returns: the CollationKey for the given String based on this Collator's collation rules. If the source String is null, a null CollationKey is returned. - `java.text.CollationKey`
(get-decomposition this)
Get the decomposition mode of this Collator. Decomposition mode determines how Unicode composed characters are handled. Adjusting decomposition mode allows the user to select between faster and more complete collation behavior. The three values for decomposition mode are:
NO_DECOMPOSITION, CANONICAL_DECOMPOSITION FULL_DECOMPOSITION.
See the documentation for these three constants for a description of their meaning.
returns: the decomposition mode - int
Get the decomposition mode of this Collator. Decomposition mode determines how Unicode composed characters are handled. Adjusting decomposition mode allows the user to select between faster and more complete collation behavior. The three values for decomposition mode are: NO_DECOMPOSITION, CANONICAL_DECOMPOSITION FULL_DECOMPOSITION. See the documentation for these three constants for a description of their meaning. returns: the decomposition mode - `int`
(get-strength this)
Returns this Collator's strength property. The strength property determines the minimum level of difference considered significant during comparison. See the Collator class description for an example of use.
returns: this Collator's current strength property. - int
Returns this Collator's strength property. The strength property determines the minimum level of difference considered significant during comparison. See the Collator class description for an example of use. returns: this Collator's current strength property. - `int`
(hash-code this)
Generates the hash code for this Collator.
returns: a hash code value for this object. - int
Generates the hash code for this Collator. returns: a hash code value for this object. - `int`
(set-decomposition this decomposition-mode)
Set the decomposition mode of this Collator. See getDecomposition for a description of decomposition mode.
decomposition-mode - the new decomposition mode. - int
throws: java.lang.IllegalArgumentException - If the given value is not a valid decomposition mode.
Set the decomposition mode of this Collator. See getDecomposition for a description of decomposition mode. decomposition-mode - the new decomposition mode. - `int` throws: java.lang.IllegalArgumentException - If the given value is not a valid decomposition mode.
(set-strength this new-strength)
Sets this Collator's strength property. The strength property determines the minimum level of difference considered significant during comparison. See the Collator class description for an example of use.
new-strength - the new strength value. - int
throws: java.lang.IllegalArgumentException - If the new strength value is not one of PRIMARY, SECONDARY, TERTIARY or IDENTICAL.
Sets this Collator's strength property. The strength property determines the minimum level of difference considered significant during comparison. See the Collator class description for an example of use. new-strength - the new strength value. - `int` throws: java.lang.IllegalArgumentException - If the new strength value is not one of PRIMARY, SECONDARY, TERTIARY or IDENTICAL.
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