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From "Eric Pugh" <ep...@upstate.com>
Subject RE: [COLLECTIONS/BEANUTILS] Is there a comparator that can dynamically pick a method to call on a bean?
Date Fri, 07 Jun 2002 17:16:41 GMT
Works for me..  For my application, if there was a good comparator, then I
would probably wrap up my code in something that combined ReverseComparator
and BeanMethodComparartor properly...

I guess I was just kinda tossing it out as an example..  If there is
interest in adding it to CVS, I will make the changes, change the package
class and add licesnising etc....

Eric

-----Original Message-----
From: Henri Yandell [mailto:bayard@generationjava.com]
Sent: Friday, June 07, 2002 11:21 AM
To: Jakarta Commons Developers List
Subject: RE: [COLLECTIONS/BEANUTILS] Is there a comparator that can
dynamically pick a method to call on a bean?


-1 to the ASC/DESC bit. That shouldn't be in comparators in my opinion,
instead use the ReverseComparator.

What is Polarity vs Property?

On Fri, 7 Jun 2002, Eric Pugh wrote:

> I forged ahead..  I had a need to sort in asc/desc...  so I have added a
> sortPolarity and sortProperty methods..
>
> Here is what I created...
>
> package com.upstate.util;
>
> import org.apache.commons.beanutils.WrapDynaBean;
> import org.apache.commons.beanutils.*;
>
> import org.apache.log4j.Category;
>
> /**
>  *  Description of the Class
>  *
>  *@author     epugh
>  *@created    May 5, 2002
>  */
> public class BeanMethodComparator implements java.util.Comparator {
>
> 	public final static String ASC = "ASC";
> 	public final static String DESC = "DESC";
>
> 	private static Category log = Category.getInstance(
> BeanMethodComparator.class.getName() );
> 	private String sortProperty;
> 	private String sortPolarity = "ASC";
>
> 	/**  Constructor for the BeanMethodComparator object */
> 	public BeanMethodComparator() { }
>
> 	/**
> 	 *  Constructor for the BeanMetodComparator object
> 	 *
> 	 *@param  sortProperty  Description of Parameter
> 	 *@param  sortPolarity  Description of Parameter
> 	 */
> 	public BeanMethodComparator( String sortProperty, String sortPolarity ) {
> 		setSortProperty( sortProperty );
> 		setSortPolarity( sortPolarity );
> 	}
>
> 	/**
> 	 *  Sets the sortProperty attribute of the SortDaughterboard object
> 	 *
> 	 *@param  sortProperty  The new sortProperty value
> 	 */
> 	public void setSortProperty( String sortProperty ) {
> 		this.sortProperty = sortProperty;
> 	}
>
> 	/**
> 	 *  Sets the sortPolarity attribute of the SortDaughterboard object
> 	 *
> 	 *@param  sortPolarity                            The new sortPolarity
> value.
> 	 *      Can be either "ASC"/"DESC".
> 	 *@exception  java.lang.IllegalArgumentException  Thrown if you pass in a
> bad
> 	 *      sortPolarity.
> 	 */
> 	public void setSortPolarity( String sortPolarity )
> 		throws java.lang.IllegalArgumentException {
> 		sortPolarity = sortPolarity.toUpperCase();
> 		if ( sortPolarity.equals( ASC ) || sortPolarity.equals( DESC ) ) {
> 			throw new java.lang.IllegalArgumentException( "The argument:" +
> sortPolarity + " was invalid." );
> 		}
> 		this.sortPolarity = sortPolarity;
> 	}
>
> 	/**
> 	 *  Gets the sortPolarity attribute of the SortDaughterboard object
> 	 *
> 	 *@return    The sortPolarity value
> 	 */
> 	public String getSortPolarity() {
> 		return sortPolarity;
> 	}
>
>
> 	/**
> 	 *  Gets the sortProperty attribute of the SortDaughterboard object
> 	 *
> 	 *@return    The sortProperty value
> 	 */
> 	public String getSortProperty() {
> 		return sortProperty;
> 	}
>
> 	/**
> 	 *  Description of the Method
> 	 *
> 	 *@param  o1  Description of Parameter
> 	 *@param  o2  Description of Parameter
> 	 *@return     Description of the Returned Value
> 	 */
> 	public int compare( Object o1, Object o2 ) {
> 		try {
> 			WrapDynaBean bean1 = new WrapDynaBean( o1 );
> 			WrapDynaBean bean2 = new WrapDynaBean( o2 );
>
> 			Comparable value1 = (Comparable) bean1.get( sortProperty );
> 			Comparable value2 = (Comparable) bean2.get( sortProperty );
>
> 			int sort = 0;
>
> 			if ( ( value1 == null ) & ( value2 == null ) ) {
> 				sort = 0;
> 			}
> 			else if ( value1 == null & value2 != null ) {
> 				sort = 1;
> 			}
> 			else if ( value1 != null & value2 == null ) {
> 				sort = -1;
> 			}
> 			else {
> 				sort = value1.compareTo( value2 );
> 			}
>
> 			if ( sortPolarity.equals( DESC ) ) {
> 				sort = sort * -1;
> 			}
>
> 			return sort;
> 		}
>
> 		catch ( Exception e ) {
> 			log.error( "Problem in Sort. sortPolarity:" + sortPolarity + ",
> sortProperty:" + sortProperty, e );
> 			return 0;
> 		}
> 	}
>
> }
>
> Eric Pugh
>
>
> -----Original Message-----
> From: Henri Yandell [mailto:bayard@generationjava.com]
> Sent: Friday, June 07, 2002 10:50 AM
> To: Jakarta Commons Developers List
> Subject: Re: [COLLECTIONS/BEANUTILS] Is there a comparator that can
> dynamically pick a method to call on a bean?
>
>
>
> I don't think there is one in Commons yet. I've had one for myself for a
> bit and it can be a lifesaver sometimes.
>
> BeanComparator bc = new BeanComparator("[1]"); was very sweet when I
> realised that would work :) Not just Beans but also arrays/collections.
>
> I'm +1 for a BeanComparator, +1 in that I plan to do it sometime but have
> not had the time to learn the Jakarta BeanUtils and stop using my own.
>
> Hen
>
> On Fri, 7 Jun 2002, Eric Pugh wrote:
>
> > Hi all,
> >
> > I have a series of Torque objects that I want to sort.  Sometimes I want
> to
> > sort by MethodA, sometiems by MethodB.  (Basically mapping onto all the
> > columns in my database).
> >
> > Right now, I have a comparator compare method that looks like this:
> > public int compare( Object o1, Object o2 ) {
> > 		Daughterboard db1 = (Daughterboard) o1;
> > 		Daughterboard db2 = (Daughterboard) o2;
> > 		int sort = 0;
> > 		if ( sortMethod.equals( "ScintillationFileNumber" ) ) {
> > 			/*
> > 			 *  if ( db1 == null == db2 ) {
> > 			 *  return 0;
> > 			 *  }
> > 			 *  else if (db1 == null &&
> > 			 */
> > 			sort = Strings.clean( db1.getScintillationFileNumber() ).compareTo(
> > Strings.clean( db2.getScintillationFileNumber() ) );
> >
> > 		}
> > 		else if ( sortMethod.equals( "DaughterboardId" ) ) {
> > 			sort = db1.getDaughterboardId().compareTo(
db2.getDaughterboardId() );
> > 		}
> > 		if ( sortPolarity.equals( "desc" ) ) {
> > 			sort = sort * -1;
> > 		}
> >
> > 		return sort;
> > 	}
> >
> > What I really want to do is pass in a sortMethod like
> > ScintillationFileNumber, and dynamically call the objects getter for
that
> > name.  If I wrap my object in a WrapDynaBean, and use that to call the
> data,
> > will is actually change the ordering of my objects?  Or should I just
use
> > the WrapDynaBean locally inside of my compare method to facilitate
calling
> > the methods?
> >
> > First time using BeanUtils, but it looks great..
> >
> > Lastly, would a comparator like this be something of general interest to
> add
> > to the collections list of comparators?
> >
> > Eric
> >
> >
> >
> > --
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> >
> >
>
>
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