String for under a particular Collator. This
* value may be compared bitwise against another CollationKey
* representing a different String under the same
* Collator in a manner than is usually more efficient than
* using the raw Collator compare methods. There is overhead
* associated with calculating this value, so it is generally not
* advisable to compute CollationKey's unless multiple
* comparisons against a String will be done. (For example,
* in a sort routine).
*
* This class cannot be instantiated directly. Instead, a
* CollationKey is created by calling the
* getCollationKey method on an instance of Collator.
*
* @author Aaron M. Renn (arenn@urbanophile.com)
* @author Tom Tromey (tromey@cygnus.com)
* @date March 25, 1999
*/
public final class CollationKey implements Comparable
{
/**
* This is the Collator this object was created from.
*/
private Collator collator;
/**
* This is the String this object represents.
*/
private String originalText;
/**
* This is the bit value for this key.
*/
private byte[] key;
CollationKey (Collator collator, String originalText, byte[] key)
{
this.collator = collator;
this.originalText = originalText;
this.key = key;
}
/**
* This method compares the specified object to this one. An integer is
* returned which indicates whether the specified object is less than,
* greater than, or equal to this object.
*
* @param ck The CollationKey to compare against this one.
*
* @return A negative integer if this object is less than the specified object, 0 if it is equal or a positive integer if it is greater than the specified object.
*/
public int compareTo (CollationKey ck)
{
int max = Math.min (key.length, ck.key.length);
for (int i = 0; i < max; ++i)
{
if (key[i] != ck.key[i])
return key[i] - ck.key[i];
}
return key.length - ck.key.length;
}
/**
* This method compares the specified object to this one. The specified
* object must be an instance of CollationKey or an exception
* will be thrown. An integer is returned which indicates whether the
* specified object is less than, greater than, or equal to this object.
*
* @param obj The Object to compare against this one.
*
* @return A negative integer if this object is less than the specified object, 0 if it is equal or a positive integer if it is greater than the specified object.
*/
public int compareTo (Object obj)
{
return compareTo ((CollationKey) obj);
}
/**
* This method tests the specified Object for equality with
* this object. This will be true if and only if:
*
*
nullCollationKey.Collator
* as this object.Object to test for equality.
*
* @return true if the specified object is equal to this one, false otherwise.
*/
public boolean equals (Object obj)
{
if (! (obj instanceof CollationKey))
return false;
CollationKey ck = (CollationKey) obj;
if (ck.collator != collator)
return false;
if (!ck.getSourceString ().equals (getSourceString ()))
return false;
if (!ck.toByteArray ().equals (toByteArray ()))
return false;
return true;
}
/**
* This method returns the String that this object was created
* from.
*
* @return The source String for this object.
*/
public String getSourceString()
{
return originalText;
}
/**
* This method returns a hash value for this object. The hash value
* returned will be the hash code of the bit key so that identical bit
* keys will return the same value.
*
* @return A hash value for this object.
*/
public int hashCode()
{
// We just follow BitSet instead of thinking up something new.
long h = originalText.hashCode();
for (int i = key.length - 1; i >= 0; --i)
h ^= key[i] * (i + 1);
return (int) ((h >> 32) ^ h);
}
/**
* This method returns the collation bit sequence as a byte array.
*
* @param A byte array containing the collation bit sequence.
*/
public byte[] toByteArray()
{
return key;
}
}