CompoundKey.java

package edu.northwestern.at.utils;

/*	Please see the license information at the end of this file. */

import java.io.Serializable;
import java.util.*;

/**	A compound key class for collections.
 */

public class CompoundKey implements XCloneable , Comparable, Serializable
{
    /** Object array of key values.  Key values should be simple objects.
     *
     *	<p>
     *	The key value is declared final because its values should not
     *	be changed once it is defined.
     *	</p>
     */

	protected final Comparable keyValues[];

    /**	Create a CompoundKey.
     *
     *	@param	keyValues	Values of the key as an array.
     *
     *	<p>
     *	Each key value must implement the comparable interface.
     *	</p>
     */

	public CompoundKey( Comparable keyValues[] )
    {
		this.keyValues = keyValues;
	}

    /**	Create a CompoundKey with one value.
     *
     *	@param	row    	"Row" value.
     */

	public CompoundKey( Comparable row )
	{
		this( new Comparable[]{ row } );
	}

    /**	Create a CompoundKey with two values.
     *
     *	@param	row    	"Row" value.
     *	@param	column	"Column" value.
     */

	public CompoundKey( Comparable row , Comparable column )
	{
		this( new Comparable[]{ row , column } );
	}

    /**	Create a CompoundKey with two values.
     *
     *	@param	row    	"Row" value.
     *	@param	column	"Column" value.
     *	@param	slice	"Slice" value.
     */

	public CompoundKey
	(
		Comparable row ,
		Comparable column ,
		Comparable slice
	)
	{
		this( new Comparable[]{ row , column , slice } );
	}

    /**	Check if another object is equal to this one.
     *
     *	@param	object  Other object to test for equality.
     *
     *	@return			true if other object is equal to this one.
     */

	public boolean equals( Object object )
	{
		return
			java.util.Arrays.equals
			(
				this.keyValues ,
				((CompoundKey)object).keyValues
			);
	}

 	/**	Compare this key with another.
 	 *
 	 *	@param	object		The other CompoundKey.
 	 *
	 *	@return				> 0 if the other key is less than this one,
	 *						= 0 if the two keys are equal,
	 *						< 0 if the other key is greater than this one.
 	 *
 	 *	<p>
 	 *	We use compareTo on the array entries in the key.
 	 *	This may not give the desired result if the array entries
 	 *	are themselves arrays.
 	 *	</p>
 	 */

	@SuppressWarnings("unchecked")
	public int compareTo( Object object )
	{
		int result	= 0;

		if ( ( object == null ) ||
			!( object instanceof CompoundKey ) )
		{
			result	= Integer.MIN_VALUE;
		}
		else
		{
			CompoundKey otherKey	= (CompoundKey)object;

			int minKeyValuesLength	=
				Math.min( keyValues.length , otherKey.keyValues.length );

			for ( int i = 0 ; i < minKeyValuesLength ; i++ )
			{
				result	=
					keyValues[ i ].compareTo( otherKey.keyValues[ i ] );

				if ( result != 0 ) break;
			}

			if ( result == 0 )
			{
				if ( keyValues.length > otherKey.keyValues.length )
				{
					result	= 1;
				}
				else if ( keyValues.length < otherKey.keyValues.length )
				{
					result	= -1;
				}
			}
		}

		return result;
	}

    /**	Get the hash code of the keys.
     *
     *	@return		The hash code.
     */

	public int hashCode()
	{
		return java.util.Arrays.hashCode( keyValues );
	}

	/**	Return a string representation of this object.
	 *
	 *	@return		A string representation of this object.
	 */

	public String toString()
	{
		return "" + Arrays.asList( keyValues );
	}

	/**	Get key values.
	 *
	 *	@return		Object array of key values.
	 */

	public Comparable[] getKeyValues()
	{
		return keyValues;
	}

	/**	Return a shallow cloned copy of this object.
	 *
	 *	@return		Shallow clone of this object.
	 *
	 *	@throws		CloneNotSupportedException which should never happen.
	 */

	public Object clone()
	{
		try
		{
			return super.clone();
		}
		catch ( CloneNotSupportedException e )
		{
			throw new InternalError();
		}
	}
}

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   Northwestern University
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