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.
*
* {@code
* // 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());
* }
*
*
* @see Collator
* @see RuleBasedCollator
* @author Helena Shih
*/
public abstract class CollationKey implements Comparable