framework/src/net/sf/tapestry/event/ObservedChangeEvent.java

/*
 *  ====================================================================
 *  The Apache Software License, Version 1.1
 *
 *  Copyright (c) 2002 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 acknowledgment:
 *  "This product includes software developed by the
 *  Apache Software Foundation (http://www.apache.org/)."
 *  Alternately, this acknowledgment may appear in the software itself,
 *  if and wherever such third-party acknowledgments normally appear.
 *
 *  4. The names "Apache" and "Apache Software Foundation" and
 *  "Apache Tapestry" must not be used to endorse or promote products
 *  derived from this software without prior written permission. For
 *  written permission, please contact apache@apache.org.
 *
 *  5. Products derived from this software may not be called "Apache",
 *  "Apache Tapestry", nor may "Apache" appear in their name, without
 *  prior written permission of the Apache Software Foundation.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 *  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 *  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 *  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *  ====================================================================
 *
 *  This software consists of voluntary contributions made by many
 *  individuals on behalf of the Apache Software Foundation.  For more
 *  information on the Apache Software Foundation, please see
 *  <http://www.apache.org/>.
 */
package net.sf.tapestry.event;

import java.io.Serializable;
import java.util.EventObject;

import net.sf.tapestry.IComponent;
import net.sf.tapestry.Tapestry;

/**
 * Event which describes a change to a particular {@link IComponent}.
 *
 * @author Howard Ship
 * @version $Id$
 * 
 **/

public class ObservedChangeEvent extends EventObject
{
    private IComponent component;
    private String propertyName;
    private Serializable newValue;

    public ObservedChangeEvent(IComponent component, String propertyName, char newValue)
    {
        this(component, propertyName, new Character(newValue));
    }

    public ObservedChangeEvent(IComponent component, String propertyName, byte newValue)
    {
        this(component, propertyName, new Byte(newValue));
    }

    public ObservedChangeEvent(IComponent component, String propertyName, short newValue)
    {
        this(component, propertyName, new Short(newValue));
    }

    public ObservedChangeEvent(IComponent component, String propertyName, int newValue)
    {
        this(component, propertyName, new Integer(newValue));
    }

    public ObservedChangeEvent(IComponent component, String propertyName, long newValue)
    {
        this(component, propertyName, new Long(newValue));
    }

    public ObservedChangeEvent(IComponent component, String propertyName, double newValue)
    {
        this(component, propertyName, new Double(newValue));
    }

    public ObservedChangeEvent(IComponent component, String propertyName, float newValue)
    {
        this(component, propertyName, new Float(newValue));
    }

    /**
     *  Creates the event.  The new value must be null, or be a serializable object.
     *  (It is declared as Object as a concession to the Java 2 collections framework, where
     *  the implementations are serializable but the interfaces (Map, List, etc.) don't
     *  extend Serializable ... so we wait until runtime to check).
     *
     *  @param component The component (not necessarily a page) whose property changed.
     *  @param propertyName the name of the property which was changed.
     *  @param newValue The new value of the property. 
     *
     *  @throws IllegalArgumentException if propertyName is null, or
     *  if the new value is not serializable
     *
     **/

    public ObservedChangeEvent(IComponent component, String propertyName, Object newValue)
    {
        super(component);

        if (propertyName == null)
            throw new IllegalArgumentException(
                Tapestry.getString("ObservedChangeEvent.null-property-name", component));

        if (newValue != null && !(newValue instanceof Serializable))
            throw new IllegalArgumentException(Tapestry.getString("ObservedChangeEvent.must-be-serializable"));

        this.component = component;
        this.propertyName = propertyName;
        this.newValue = (Serializable) newValue;
    }

    public ObservedChangeEvent(IComponent component, String propertyName, boolean newValue)
    {
        this(component, propertyName, new Boolean(newValue));
    }

    /**
     *  Constructor for an unknown change event.  The receiver must acknowledge
     *  that the observed object changed.  This is used when a property of
     *  the component is itself is a data holder (such as a Collection object) and
     *  it changes.
     *
     **/

    public ObservedChangeEvent(IComponent component)
    {
        super(component);

        this.component = component;
    }

    public IComponent getComponent()
    {
        return component;
    }

    public Serializable getNewValue()
    {
        return newValue;
    }

    public String getPropertyName()
    {
        return propertyName;
    }

}