java.lang.Object java.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() );
Method Summary | |
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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 |
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clone , finalize , getClass , notify , notifyAll , toString , wait , wait , wait |
Methods inherited from interface java.lang. Comparable |
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compareTo |
Method Detail |
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public int compareTo(CollationKey target)
public int compareTo(Object o)
public boolean equals(Object target)
public int hashCode()
public String getSourceString()
public byte[] toByteArray()