/*

  * Licensed to the Apache Software Foundation (ASF) under one or more

  * contributor license agreements.  See the NOTICE file distributed with

  * this work for additional information regarding copyright ownership.

  * The ASF licenses this file to You under the Apache License, Version 2.0

  * (the "License"); you may not use this file except in compliance with

  * the License.  You may obtain a copy of the License at

  *

  *     http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.apache.commons.configuration.event;

 import java.util.EventObject;

 /**

  * <p>

  * An event class for reporting updates on a configuration object.

  * </p>

  * <p>

  * Event objects of this type are used for "raw" events, i.e.

  * unfiltered modifications of any kind. A level with semantically higher events

  * (e.g. for property changes) may be built on top of this fundamental event

  * mechanism.

  * </p>

  * <p>

  * Each event can contain the following data:

  * <ul>

  * <li>A source object, which is usually the configuration object that was

  * modified.</li>

  * <li>The event's type. This is a numeric value that corresponds to constant

  * declarations in concrete configuration classes. It describes what exactly has

  * happended.</li>

  * <li>If available, the name of the property whose modification caused the

  * event.</li>

  * <li>If available, the value of the property that caused this event.</li>

  * <li>A flag whether this event was generated before or after the update of

  * the source configuration. A modification of a configuration typically causes

  * two events: one event before and one event after the modification is

  * performed. This allows event listeners to react at the correct point of time.</li>

  * </ul>

  * </p>

  * <p>

  * The following standard events are generated by typical configuration

  * implementations (the constants for the event types are defined in

  * <code>{@link org.apache.commons.configuration.AbstractConfiguration}</code>):

  * <dl>

  * <dt>EVENT_ADD_PROPERTY</dt>

  * <dd>This event is triggered for each call of the <code>addProperty()</code>

  * method of a configuration object. It contains the name of the property, to

  * which new data is added, and the value object that is added to this property

  * (this may be an array or a list if multiple values are added).</dd>

  * <dt>EVENT_SET_PROPERTY</dt>

  * <dd>Calling the <code>setProperty()</code> method triggers this event. The

  * event object stores the name of the affected property and its new value.</dd>

  * <dt>EVENT_CLEAR_PROPERTY</dt>

  * <dd>If a property is removed from a configuration (by calling the

  * <code>clearProperty()</code> method), an event of this type is fired. In

  * this case the event object only stores the name of the removed property, the

  * value is <b>null</b>.</dd>

  * <dt>EVENT_CLEAR</dt>

  * <dd>This event is fired when the whole configuration is cleared. The

  * corresponding event object contains no additional data.</dd>

  * </dl>

  * </p>

  *

  * @author <a

  * href="http://jakarta.apache.org/commons/configuration/team-list.html">Commons

  * Configuration team</a>

  * @version $Id: ConfigurationEvent.java 443105 2006-09-13 20:04:01Z oheger $

  * @since 1.3

  */

 public class ConfigurationEvent extends EventObject

 {

     /**

      * The serial version UID.

      */

     private static final long serialVersionUID = 3277238219073504136L;

     /** Stores the event type. */

     private int type;

     /** Stores the property name. */

     private String propertyName;

     /** Stores the property value. */

     private Object propertyValue;

     /** Stores the before update flag. */

     private boolean beforeUpdate;

     /**

      * Creates a new instance of <code>ConfigurationEvent</code> and

      * initializes it.

      *

      * @param source the event source

      * @param type the event's type

      * @param propertyName the name of the affected property

      * @param propertyValue the value of the affected property

      * @param beforeUpdate the before update flag

      */

     public ConfigurationEvent(Object source, int type, String propertyName,

             Object propertyValue, boolean beforeUpdate)

     {

         super(source);

         this.type = type;

         this.propertyName = propertyName;

         this.propertyValue = propertyValue;

         this.beforeUpdate = beforeUpdate;

     }

     /**

      * Returns the name of the affected property. This can be <b>null</b> if no

      * property change has lead to this event.

      *

      * @return the name of the property

      */

     public String getPropertyName()

     {

         return propertyName;

     }

     /**

      * Returns the value of the affected property if available.

      *

      * @return the value of the property; can be <b>null</b>

      */

     public Object getPropertyValue()

     {

         return propertyValue;

     }

     /**

      * Returns the type of this event. This describes the update process that

      * caused this event.

      *

      * @return the event's type

      */

     public int getType()

     {

         return type;

     }

     /**

      * Returns a flag if this event was generated before or after an update.

      *

      * @return <b>true</b> if this event was generated before an update;

      * <b>false</b> otherwise

      */

     public boolean isBeforeUpdate()

     {

         return beforeUpdate;

     }

 }