SoftArticleAdapter.java

// BlogBridge -- RSS feed reader, manager, and web based service
// Copyright (C) 2002-2006 by R. Pito Salas
//
// This program is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free Software Foundation;
// either version 2 of the License, or (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License along with this program;
// if not, write to the Free Software Foundation, Inc., 59 Temple Place,
// Suite 330, Boston, MA 02111-1307 USA
//
// Contact: R. Pito Salas
// mailto:pitosalas@users.sourceforge.net
// More information: about BlogBridge
// http://www.blogbridge.com
// http://sourceforge.net/projects/blogbridge
//
// $Id: SoftArticleAdapter.java,v 1.2 2006/01/08 04:48:16 kyank Exp $
//

package com.salas.bb.domain.utils;

import com.salas.bb.domain.IArticle;
import com.salas.bb.domain.IArticleListener;

import java.lang.ref.SoftReference;

/**
 * Soft-reference article adapter. It removes hard link between
 * source of events and listener, allowing the listener to be garbage collected.
 */
public class SoftArticleAdapter extends SoftReference implements IArticleListener
{
    /**
     * Wraps the listener.
     *
     * @param listener to wrap.
     */
    public SoftArticleAdapter(IArticleListener listener)
    {
        super(listener);
    }

    /**
     * Invoked when the property of the article has been changed.
     *
     * @param article  article.
     * @param property property of the article.
     * @param oldValue old property value.
     * @param newValue new property value.
     */
    public void propertyChanged(IArticle article, String property, Object oldValue, Object newValue)
    {
        IArticleListener listener = (IArticleListener)get();

        if (listener == null)
        {
            article.removeListener(this);
        } else
        {
            listener.propertyChanged(article, property, oldValue, newValue);
        }
    }
}