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JavaTM 2 Platform Std. Ed. v1.4.2 |
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java.lang.Objectjava.text.CollationKey
A CollationKey represents a String under the
rules of a specific Collator object. Comparing two
CollationKeys returns the relative order of the
Strings they represent. Using CollationKeys
to compare Strings is generally faster than using
Collator.compare. Thus, when the Strings
must be compared multiple times, for example when sorting a list
of Strings. It's more efficient to use CollationKeys.
You can not create CollationKeys directly. Rather,
generate them by calling Collator.getCollationKey.
You can only compare CollationKeys generated from
the same Collator object.
Generating a CollationKey for a String
involves examining the entire String
and converting it to series of bits that can be compared bitwise. This
allows fast comparisons once the keys are generated. The cost of generating
keys is recouped in faster comparisons when Strings need
to be compared many times. On the other hand, the result of a comparison
is often determined by the first couple of characters of each String.
Collator.compare examines only as many characters as it needs which
allows it to be faster when doing single comparisons.
The following example shows how CollationKeys might be used
to sort a list of Strings.
// Create an array of CollationKeys for the Strings to be sorted.
Collator myCollator = Collator.getInstance();
CollationKey[] keys = new CollationKey[3];
keys[0] = myCollator.getCollationKey("Tom");
keys[1] = myCollator.getCollationKey("Dick");
keys[2] = myCollator.getCollationKey("Harry");
sort( keys );
//...
// Inside body of sort routine, compare keys this way
if( keys[i].compareTo( keys[j] ) > 0 )
// swap keys[i] and keys[j]
//...
// Finally, when we've returned from sort.
System.out.println( keys[0].getSourceString() );
System.out.println( keys[1].getSourceString() );
System.out.println( keys[2].getSourceString() );
Collator,
RuleBasedCollator| Method Summary | |
int |
compareTo(CollationKey target)
Compare this CollationKey to the target CollationKey. |
int |
compareTo(Object o)
Compares this CollationKey with the specified Object for order. |
boolean |
equals(Object target)
Compare this CollationKey and the target CollationKey for equality. |
String |
getSourceString()
Returns the String that this CollationKey represents. |
int |
hashCode()
Creates a hash code for this CollationKey. |
byte[] |
toByteArray()
Converts the CollationKey to a sequence of bits. |
| Methods inherited from class java.lang.Object |
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
| Method Detail |
public int compareTo(CollationKey target)
target - target CollationKey
Collator.compare(java.lang.String, java.lang.String)public int compareTo(Object o)
compareTo in interface Comparableo - the Object to be compared.
ClassCastException - the specified Object is not a
CollationKey.Comparablepublic boolean equals(Object target)
equals in class Objecttarget - the CollationKey to compare to.
Object.hashCode(),
Hashtablepublic int hashCode()
hashCode in class ObjectObject.equals(java.lang.Object),
Hashtablepublic String getSourceString()
public byte[] toByteArray()
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JavaTM 2 Platform Std. Ed. v1.4.2 |
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Copyright 2003 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.