Added in API level 1

Collator

abstract class Collator : Comparator<Any!>, Cloneable

kotlin.Any
↳	java.text.Collator

Known Direct Subclasses

RuleBasedCollator

The class is a concrete subclass of Collator that provides a simple, data-driven, table collator.

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.

<code>// Compare two strings in the default locale
  Collator myCollator = Collator.getInstance();
  if( myCollator.compare("abc", "ABC") &lt; 0 )
      System.out.println("abc is less than ABC");
  else
      System.out.println("abc is greater than or equal to ABC");
  </code>

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 dependent. 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.

Summary

Constants
static Int	`CANONICAL_DECOMPOSITION` Decomposition mode value.
static Int	`FULL_DECOMPOSITION` Decomposition mode value.
static Int	`IDENTICAL` Collator strength value.
static Int	`NO_DECOMPOSITION` Decomposition mode value.
static Int	`PRIMARY` Collator strength value.
static Int	`SECONDARY` Collator strength value.
static Int	`TERTIARY` Collator strength value.

Protected constructors
`Collator()` Default constructor.

Public methods
open Any	`clone()` Returns a new collator with the same decomposition mode and strength value as this collator.
abstract Int	`compare(source: String!, target: String!)` Compares the source string to the target string according to the collation rules for this Collator.
open Int	`compare(o1: Any!, o2: Any!)` Compares its two arguments for order.
open Boolean	`equals(source: String!, target: String!)` Convenience method for comparing the equality of two strings based on this Collator's collation rules.
open Boolean	`equals(other: Any?)` Compares the equality of two Collators.
open static Array<Locale!>!	`getAvailableLocales()` Returns an array of all locales for which the `getInstance` methods of this class can return localized instances.
abstract CollationKey!	`getCollationKey(source: String!)` Transforms the String into a series of bits that can be compared bitwise to other CollationKeys.
open Int	`getDecomposition()` Get the decomposition mode of this Collator.
open static Collator!	`getInstance()` Gets the Collator for the current default locale.
open static Collator!	`getInstance(desiredLocale: Locale!)` Gets the Collator for the desired locale.
open Int	`getStrength()` Returns this Collator's strength property.
abstract Int	`hashCode()` Generates the hash code for this Collator.
open Unit	`setDecomposition(decompositionMode: Int)` Set the decomposition mode of this Collator.
open Unit	`setStrength(newStrength: Int)` Sets this Collator's strength property.

Inherited functions

From class Comparator

`Comparator<T>!`	`reversed()` Returns a comparator that imposes the reverse ordering of this comparator.
`Comparator<T>!`	`thenComparing(other: Comparator<in T>!)` Returns a lexicographic-order comparator with another comparator. If this `Comparator` considers two elements equal, i.e. `compare(a, b) == 0`, `other` is used to determine the order. The returned comparator is serializable if the specified comparator is also serializable.
`Comparator<T>!`	`thenComparing(keyExtractor: Function<in T, out U>!, keyComparator: Comparator<in U>!)` Returns a lexicographic-order comparator with a function that extracts a key to be compared with the given `Comparator`.
`Comparator<T>!`	`thenComparing(keyExtractor: Function<in T, out U>!)` Returns a lexicographic-order comparator with a function that extracts a `Comparable` sort key.
`Comparator<T>!`	`thenComparingDouble(keyExtractor: ToDoubleFunction<in T>!)` Returns a lexicographic-order comparator with a function that extracts a `double` sort key.
`Comparator<T>!`	`thenComparingInt(keyExtractor: ToIntFunction<in T>!)` Returns a lexicographic-order comparator with a function that extracts an `int` sort key.
`Comparator<T>!`	`thenComparingLong(keyExtractor: ToLongFunction<in T>!)` Returns a lexicographic-order comparator with a function that extracts a `long` sort key.

Constants

CANONICAL_DECOMPOSITION

Added in API level 1

static val CANONICAL_DECOMPOSITION: Int

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 Standard Annex #15: Unicode Normalization Forms.

Value: 1

See Also

java.text.Collator#getDecomposition
java.text.Collator#setDecomposition

FULL_DECOMPOSITION

Added in API level 1

static val FULL_DECOMPOSITION: Int

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 Standard Annex #15: Unicode Normalization Forms.

Value: 2

See Also

java.text.Collator#getDecomposition
java.text.Collator#setDecomposition

IDENTICAL

Added in API level 1

static val IDENTICAL: Int

Collator strength value. When set, all differences are considered significant during comparison. The assignment of strengths to language features is locale dependent. 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.

Value: 3

NO_DECOMPOSITION

Added in API level 1

static val NO_DECOMPOSITION: Int

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.

Value: 0

See Also

java.text.Collator#getDecomposition
java.text.Collator#setDecomposition

PRIMARY

Added in API level 1

static val PRIMARY: Int

Collator strength value. When set, only PRIMARY differences are considered significant during comparison. The assignment of strengths to language features is locale dependent. A common example is for different base letters ("a" vs "b") to be considered a PRIMARY difference.

Value: 0

See Also

java.text.Collator#setStrength
java.text.Collator#getStrength

SECONDARY

Added in API level 1

static val SECONDARY: Int

Collator strength value. When set, only SECONDARY and above differences are considered significant during comparison. The assignment of strengths to language features is locale dependent. A common example is for different accented forms of the same base letter ("a" vs "\u00E4") to be considered a SECONDARY difference.

Value: 1

See Also

java.text.Collator#setStrength
java.text.Collator#getStrength

TERTIARY

Added in API level 1

static val TERTIARY: Int

Collator strength value. When set, only TERTIARY and above differences are considered significant during comparison. The assignment of strengths to language features is locale dependent. A common example is for case differences ("a" vs "A") to be considered a TERTIARY difference.

Value: 2

See Also

java.text.Collator#setStrength
java.text.Collator#getStrength

Protected constructors

Collator

Added in API level 1

protected Collator()

Default constructor. This constructor is protected so subclasses can get access to it. Users typically create a Collator sub-class by calling the factory method getInstance.

See Also

Public methods

clone

Added in API level 1

open fun clone(): Any

Returns a new collator with the same decomposition mode and strength value as this collator.

Return
`Any`	a shallow copy of this collator.

Exceptions
`java.lang.CloneNotSupportedException`	if the object's class does not support the `Cloneable` interface. Subclasses that override the `clone` method can also throw this exception to indicate that an instance cannot be cloned.

See Also

java.lang.Cloneable

compare

Added in API level 1

abstract fun compare(
    source: String!, 
    target: String!
): 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.

Parameters
`source`	String!: the source string.
`target`	String!: the target string.

Return
`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.

See Also

java.text.CollationKey
java.text.Collator#getCollationKey

compare

Added in API level 1

open fun compare(
    o1: Any!, 
    o2: Any!
): Int

Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

This implementation merely returns compare((String)o1, (String)o2) .

Parameters
`o1`	Any!: the first object to be compared.
`o2`	Any!: the second object to be compared.

Return
`Int`	a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

Exceptions
`java.lang.NullPointerException`	if an argument is null and this comparator does not permit null arguments
`java.lang.ClassCastException`	the arguments cannot be cast to Strings.

See Also

java.util.Comparator

equals

Added in API level 1

open fun equals(
    source: String!, 
    target: String!
): Boolean

Convenience method for comparing the equality of two strings based on this Collator's collation rules.

Parameters
`source`	String!: the source string to be compared with.
`target`	String!: the target string to be compared with.

Return
`Boolean`	true if the strings are equal according to the collation rules. false, otherwise.

See Also

equals

Added in API level 1

open fun equals(other: Any?): Boolean

Compares the equality of two Collators.

Parameters
`obj`	the reference object with which to compare.
`that`	the Collator to be compared with this.

Return
`Boolean`	true if this Collator is the same as that Collator; false otherwise.

getAvailableLocales

Added in API level 1

open static fun getAvailableLocales(): Array<Locale!>!

Returns an array of all locales for which the getInstance methods of this class can return localized instances.

Return
`Array<Locale!>!`	An array of locales for which localized `Collator` instances are available.

getCollationKey

Added in API level 1

abstract fun getCollationKey(source: String!): 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.

Parameters
`source`	String!: the string to be transformed into a collation key.

Return
`CollationKey!`	the CollationKey for the given String based on this Collator's collation rules. If the source String is null, a null CollationKey is returned.

See Also

java.text.CollationKey

getDecomposition

Added in API level 1

open fun getDecomposition(): 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.

Return
`Int`	the decomposition mode

See Also

java.text.Collator#setDecomposition
java.text.Collator#NO_DECOMPOSITION
java.text.Collator#CANONICAL_DECOMPOSITION
java.text.Collator#FULL_DECOMPOSITION

getInstance

Added in API level 1

open static fun getInstance(): Collator!

Gets the Collator for the current default locale. The default locale is determined by java.util.Locale.getDefault.

Return
`Collator!`	the Collator for the default locale.(for example, en_US)

See Also

getInstance

Added in API level 1

open static fun getInstance(desiredLocale: Locale!): Collator!

Gets the Collator for the desired locale.

Parameters
`desiredLocale`	Locale!: the desired locale.

Return
`Collator!`	the Collator for the desired locale.

See Also

getStrength

Added in API level 1

open fun getStrength(): 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.

Return
`Int`	this Collator's current strength property.

See Also

java.text.Collator#setStrength
java.text.Collator#PRIMARY
java.text.Collator#SECONDARY
java.text.Collator#TERTIARY
java.text.Collator#IDENTICAL

hashCode

Added in API level 1

abstract fun hashCode(): Int

Generates the hash code for this Collator.

Return
`Int`	a hash code value for this object.

setDecomposition

Added in API level 1

open fun setDecomposition(decompositionMode: Int): Unit

Set the decomposition mode of this Collator. See getDecomposition for a description of decomposition mode.

Parameters
`decompositionMode`	Int: the new decomposition mode.

Exceptions
`java.lang.IllegalArgumentException`	If the given value is not a valid decomposition mode.

See Also

java.text.Collator#getDecomposition
java.text.Collator#NO_DECOMPOSITION
java.text.Collator#CANONICAL_DECOMPOSITION
java.text.Collator#FULL_DECOMPOSITION

setStrength

Added in API level 1

open fun setStrength(newStrength: Int): Unit

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.

Parameters
`newStrength`	Int: the new strength value.

Exceptions
`java.lang.IllegalArgumentException`	If the new strength value is not one of PRIMARY, SECONDARY, TERTIARY or IDENTICAL.

See Also

java.text.Collator#getStrength
java.text.Collator#PRIMARY
java.text.Collator#SECONDARY
java.text.Collator#TERTIARY
java.text.Collator#IDENTICAL