/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2000 Intersect Software Corporation

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see http://www.gnu.org
*/

package net.wotonomy.util;

import java.io.Serializable;
import java.util.Comparator;

/**
* A Comparator that will sort elements based on the
* property specified in the constructor.
*
* @author michael@mpowers.net
* @author $Author: mpowers $
* @version $Revision: 1.1.1.1 $
*/
public class PropertyComparator implements Comparator, Serializable
{
    private String property;

/**
* Standard constructor to configure the comparator.
* @param aProperty A property whose value is used to sort elements.
*/
    public PropertyComparator( String aProperty )
    {
		property = aProperty;
    }

    // interface Comparator

    public int compare(Object o1, Object o2)
    {
		Object v1 = Introspector.get( o1, property );
		Object v2 = Introspector.get( o2, property );
		if ( v1 instanceof Comparable )
		{
			return ((Comparable)v1).compareTo( v2 );
		}
		else
		if ( v2 instanceof Comparable )
		{
			return ((Comparable)v2).compareTo( v1 );
		}
		else
		{
			if ( v1 == null )
			{
				if ( v2 == null )
				{
					return 0; // both nulls are equal
				}
				return -1; // null is less than any object
			}
			else
			if ( v2 == null )
			{
				return 1; // any object is greater than null
			}
		}
		// last resort: compare string conversions
		return v1.toString().compareTo( v2.toString() );
	}
	
	public boolean equals( Object obj )
	{
		return ( obj instanceof PropertyComparator );	
	}
}

/*
 * $Log: PropertyComparator.java,v $
 * Revision 1.1.1.1  2000/12/21 15:52:07  mpowers
 * Contributing wotonomy.
 *
 * Revision 1.2  2000/12/20 16:25:46  michael
 * Added log to all files.
 *
 *
 */