Collator

Collator

java.text

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Java 1.1

cloneable

This class compares , orders, and sorts strings in a way appropriate for the default locale or some other specified locale. Because it is an abstract class, it cannot be instantiated directly. Instead, you must use the static getInstance( ) method to obtain an instance of a Collator subclass that is appropriate for the default or specified locale. You can use getAvailableLocales( ) to determine whether a Collator object is available for a desired locale.

Once an appropriate Collator object has been obtained, you can use the compare( ) method to compare strings. The possible return values of this method are -1, 0, and 1, which indicate , respectively, that the first string is collated before the second, that the two are equivalent for collation purposes, and that the first string is collated after the second. The equals( ) method is a convenient shortcut for testing two strings for collation equivalence.

When sorting an array of strings, each string in the array is typically compared more than once. Using the compare( ) method in this case is inefficient. A more efficient method for comparing strings multiple times is to use getCollationKey( ) for each string to create CollationKey objects. These objects can then be compared to each other more quickly than the strings themselves can be compared.

You can customize the way the Collator object performs comparisons by calling setStrength( ) . If you pass the constant PRIMARY to this method, the comparison looks only at primary differences in the strings; it compares letters but ignores accents and case differences. If you pass the constant SECONDARY , it ignores case differences but does not ignore accents. And if you pass TERTIARY (the default), the Collator object takes both accents and case differences into account in its comparison.

Figure 15-6. java.text.Collator

 public abstract class  Collator  implements java.util.Comparator<Object>,          Cloneable {  // Protected Constructors  protected  Collator  ( );  // Public Constants  public static final int  CANONICAL_DECOMPOSITION  ;  =1  public static final int  FULL_DECOMPOSITION  ;  =2  public static final int  IDENTICAL  ;  =3  public static final int  NO_DECOMPOSITION  ;  =0  public static final int  PRIMARY  ;  =0  public static final int  SECONDARY  ;  =1  public static final int  TERTIARY  ;  =2   // Public Class Methods  public static java.util.Locale[ ]  getAvailableLocales  ( );  synchronized  public static Collator  getInstance  ( );  synchronized  public static Collator  getInstance  (java.util.Locale  desiredLocale  );  synchronized   // Public Instance Methods  public abstract int  compare  (String  source  , String  target  );        public boolean  equals  (Object  that  );  Implements:  Comparator      public boolean  equals  (String  source  , String  target  );        public abstract CollationKey  getCollationKey  (String  source  );        public int  getDecomposition  ( );  synchronized  public int  getStrength  ( );  synchronized  public void  setDecomposition  (int  decompositionMode  );  synchronized  public void  setStrength  (int  newStrength  );  synchronized   // Methods Implementing Comparator   1.2  public int  compare  (Object  o1  , Object  o2  );        public boolean  equals  (Object  that  );  // Public Methods Overriding Object  public Object  clone  ( );        public abstract int  hashCode  ( );   } 

Subclasses

RuleBasedCollator