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java.text
abstract public class: Collator [javadoc | source]
java.lang.Object
   java.text.Collator

All Implemented Interfaces:
    Cloneable, Comparator

Direct Known Subclasses:
    RuleBasedCollator

Performs locale-sensitive string comparison. A concrete subclass, RuleBasedCollator , allows customization of the collation ordering by the use of rule sets.

Following the Unicode Consortium's specifications for the Unicode Collation Algorithm (UCA), there are 4 different levels of strength used in comparisons:

This {@code Collator} deals only with two decomposition modes, the canonical decomposition mode and one that does not use any decomposition. The compatibility decomposition mode {@code java.text.Collator.FULL_DECOMPOSITION} is not supported here. If the canonical decomposition mode is set, {@code Collator} handles un-normalized text properly, producing the same results as if the text were normalized in NFD. If canonical decomposition is turned off, it is the user's responsibility to ensure that all text is already in the appropriate form before performing a comparison or before getting a CollationKey .

Examples:

// 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");
}

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();
myCollator.setDecomposition(Collator.NO_DECOMPOSITION);
if (myCollator.compare("\u00e0\u0325", "a\u0325\u0300") != 0) {
    System.out.println("\u00e0\u0325 is not equal to a\u0325\u0300 without decomposition");
    myCollator.setDecomposition(Collator.CANONICAL_DECOMPOSITION);
    if (myCollator.compare("\u00e0\u0325", "a\u0325\u0300") != 0) {
        System.out.println("Error: \u00e0\u0325 should be equal to a\u0325\u0300 with decomposition");
    } else {
        System.out.println("\u00e0\u0325 is equal to a\u0325\u0300 with decomposition");
    }
} else {
    System.out.println("Error: \u00e0\u0325 should be not equal to a\u0325\u0300 without decomposition");
}
Field Summary
static final  int EQUAL     
static final  int GREATER     
static final  int LESS     
public static final  int NO_DECOMPOSITION    Constant used to specify the decomposition rule. 
public static final  int CANONICAL_DECOMPOSITION    Constant used to specify the decomposition rule. 
public static final  int FULL_DECOMPOSITION    Constant used to specify the decomposition rule. This value for decomposition is not supported. 
public static final  int PRIMARY    Constant used to specify the collation strength. 
public static final  int SECONDARY    Constant used to specify the collation strength. 
public static final  int TERTIARY    Constant used to specify the collation strength. 
public static final  int IDENTICAL    Constant used to specify the collation strength. 
 Collator icuColl     
Constructor:
 protected Collator() 
 Collator(Collator wrapper) 
Method from java.text.Collator Summary:
clone,   compare,   compare,   equals,   equals,   getAvailableLocales,   getCollationKey,   getDecomposition,   getInstance,   getInstance,   getStrength,   hashCode,   setDecomposition,   setStrength
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from java.text.Collator Detail:
 public Object clone() 
    Returns a new collator with the same decomposition mode and strength value as this collator.
 public int compare(Object object1,
    Object object2) 
    Compares two objects to determine their relative order. The objects must be strings.
 abstract public int compare(String string1,
    String string2)
    Compares two strings to determine their relative order.
 public boolean equals(Object object) 
    Compares this collator with the specified object and indicates if they are equal.
 public boolean equals(String string1,
    String string2) 
    Compares two strings using the collation rules to determine if they are equal.
 public static Locale[] getAvailableLocales() 
    Gets the list of installed java.util.Locale objects which support {@code Collator}.
 abstract public CollationKey getCollationKey(String string)
    Returns a CollationKey for the specified string for this collator with the current decomposition rule and strength value.
 public int getDecomposition() 
    Returns the decomposition rule for this collator.
 public static Collator getInstance() 
    Returns a {@code Collator} instance which is appropriate for the default {@code Locale}.
 public static Collator getInstance(Locale locale) 
    Returns a {@code Collator} instance which is appropriate for the specified {@code Locale}.
 public int getStrength() 
    Returns the strength value for this collator.
 abstract public int hashCode()
    Returns an integer hash code for this collator.
 public  void setDecomposition(int value) 
    Sets the decomposition rule for this collator.
 public  void setStrength(int value) 
    Sets the strength value for this collator.