/*
 * $Header: /home/cvspublic/jakarta-commons/beanutils/src/java/org/apache/commons/beanutils/BeanComparator.java,v 1.4 2003/01/15 21:59:38 rdonkin Exp $
 * $Revision: 1.4 $
 * $Date: 2003/01/15 21:59:38 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
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 *    permission, please contact apache@apache.org.
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 * 5. Products derived from this software may not be called "Apache"
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 * This software consists of voluntary contributions made by many
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 */

 package  org.apache.commons.beanutils;

 import  java.io.Serializable;
 import  java.util.Comparator;
 import  org.apache.commons.beanutils.PropertyUtils;
 import  org.apache.commons.collections.comparators.ComparableComparator;

/**
 * Allows you to pass the name of a method in and compare two beans.
 *
 * @author     <a href"mailto:epugh@upstate.com">Eric Pugh</a>
 */
 public   class  BeanComparator  implements  Comparator, Serializable {

     private  String property;
     private  Comparator comparator;

    /**
     * Creates a Bean comparator that calls the property specified 
     * on the objects.
     * If you pass in a null, the BeanComparator defaults to comparing
     * based on the natural order, that is java.lang.Comparable.
     *
     * @param property String name of bean property
     */
     public  BeanComparator( String property ) {
         this ( property, ComparableComparator.getInstance() );
    }

    /**
     * Creates a comparator that compares objects based on the method 
     * name of two JavaBeans.
     *
     * @param property String method name to call to compare 
     * @param comparator      Comparator to call afterwords!
     */
     public  BeanComparator( String property, Comparator comparator ) {
        setProperty( property );
         this .comparator = comparator;
    }

    /**
     * Sets the method to be called to compare two JavaBeans
     *
     * @param property String method name to call to compare 
     */
     public   void  setProperty( String property ) {
         this .property = property;
    }


    /**
     * Gets the property attribute of the BeanComparator
     *
     * @return String method name to call to compare
     */
     public  String getProperty() {
         return  property;
    }


    /**
     * Gets the Comparator being used to compare beans.
     */
     public  Comparator getComparator() {
         return  comparator;
    }


    /**
     * Compare two JavaBeans by their shared property.
     *
     * @param  o1 Object The first bean to get data from to compare against
     * @param  o2 Object The second bean to get data from to compare
     * @return int negative or positive based on order
     */
     public   int  compare( Object o1, Object o2 ) {
         try  {
            Object value1 = PropertyUtils.getProperty( o1, property );
            Object value2 = PropertyUtils.getProperty( o2, property );
             return  comparator.compare( value1, value2 );
        }
         catch  ( Exception e ) {
             throw   new  ClassCastException( e.toString() );
        }
    }

}