Collator

public abstract class Collator
extends Object implements Cloneable, Comparator<Object>

java.lang.Object
↳	java.text.Collator

Known direct subclasses

RuleBasedCollator

RuleBasedCollator The RuleBasedCollator 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.

// 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 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.

See also:

Summary

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

Protected constructors
`Collator()` Default constructor.

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

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

From interface


        
          java.util.Comparator


        abstract


        int


      compare(Object o1, Object o2)

Compares its two arguments for order.


        
        
        static
        
        <T, U>
        Comparator<Object>


      ,%20java.util.Comparator

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Collator

Summary

Constants

Protected constructors

Public methods

Inherited methods