public abstract class CollationKey extends Object implements Comparable<CollationKey>A
Stringunder the rules of a specific
Collatorobject. 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
You can not create
CollationKeys directly. Rather, generate them by calling
Collator.getCollationKey. You can only compare
CollationKeys generated from the same
Stringinvolves examining the entire
Stringand 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
Collator.compareexamines 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
// Create an array of CollationKeys for the Strings to be sorted. Collator myCollator = Collator.getInstance(); CollationKey keys = new CollationKey; keys = myCollator.getCollationKey("Tom"); keys = myCollator.getCollationKey("Dick"); keys = 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.getSourceString()); System.out.println(keys.getSourceString()); System.out.println(keys.getSourceString());
public abstract int compareTo(CollationKey target)Compare this CollationKey to the target CollationKey. The collation rules of the Collator object which created these keys are applied. Note: CollationKeys created by different Collators can not be compared.
- Specified by:
target- target CollationKey
- Returns an integer value. Value is less than zero if this is less than target, value is zero if this and target are equal and value is greater than zero if this is greater than target.
- See Also:
public String getSourceString()Returns the String that this CollationKey represents.
- the source string of this CollationKey
public abstract byte toByteArray()Converts the CollationKey to a sequence of bits. If two CollationKeys could be legitimately compared, then one could compare the byte arrays for each of those keys to obtain the same result. Byte arrays are organized most significant byte first.
- a byte array representation of the CollationKey