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    1   /*
    2    * Copyright (c) 1996, 2010, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   
   26   package java.beans;
   27   
   28   /**
   29    * A "PropertyChange" event gets delivered whenever a bean changes a "bound"
   30    * or "constrained" property.  A PropertyChangeEvent object is sent as an
   31    * argument to the PropertyChangeListener and VetoableChangeListener methods.
   32    * <P>
   33    * Normally PropertyChangeEvents are accompanied by the name and the old
   34    * and new value of the changed property.  If the new value is a primitive
   35    * type (such as int or boolean) it must be wrapped as the
   36    * corresponding java.lang.* Object type (such as Integer or Boolean).
   37    * <P>
   38    * Null values may be provided for the old and the new values if their
   39    * true values are not known.
   40    * <P>
   41    * An event source may send a null object as the name to indicate that an
   42    * arbitrary set of if its properties have changed.  In this case the
   43    * old and new values should also be null.
   44    */
   45   
   46   public class PropertyChangeEvent extends java.util.EventObject {
   47       private static final long serialVersionUID = 7042693688939648123L;
   48   
   49       /**
   50        * Constructs a new <code>PropertyChangeEvent</code>.
   51        *
   52        * @param source  The bean that fired the event.
   53        * @param propertyName  The programmatic name of the property
   54        *          that was changed.
   55        * @param oldValue  The old value of the property.
   56        * @param newValue  The new value of the property.
   57        */
   58       public PropertyChangeEvent(Object source, String propertyName,
   59                                        Object oldValue, Object newValue) {
   60           super(source);
   61           this.propertyName = propertyName;
   62           this.newValue = newValue;
   63           this.oldValue = oldValue;
   64       }
   65   
   66       /**
   67        * Gets the programmatic name of the property that was changed.
   68        *
   69        * @return  The programmatic name of the property that was changed.
   70        *          May be null if multiple properties have changed.
   71        */
   72       public String getPropertyName() {
   73           return propertyName;
   74       }
   75   
   76       /**
   77        * Gets the new value for the property, expressed as an Object.
   78        *
   79        * @return  The new value for the property, expressed as an Object.
   80        *          May be null if multiple properties have changed.
   81        */
   82       public Object getNewValue() {
   83           return newValue;
   84       }
   85   
   86       /**
   87        * Gets the old value for the property, expressed as an Object.
   88        *
   89        * @return  The old value for the property, expressed as an Object.
   90        *          May be null if multiple properties have changed.
   91        */
   92       public Object getOldValue() {
   93           return oldValue;
   94       }
   95   
   96       /**
   97        * Sets the propagationId object for the event.
   98        *
   99        * @param propagationId  The propagationId object for the event.
  100        */
  101       public void setPropagationId(Object propagationId) {
  102           this.propagationId = propagationId;
  103       }
  104   
  105       /**
  106        * The "propagationId" field is reserved for future use.  In Beans 1.0
  107        * the sole requirement is that if a listener catches a PropertyChangeEvent
  108        * and then fires a PropertyChangeEvent of its own, then it should
  109        * make sure that it propagates the propagationId field from its
  110        * incoming event to its outgoing event.
  111        *
  112        * @return the propagationId object associated with a bound/constrained
  113        *          property update.
  114        */
  115       public Object getPropagationId() {
  116           return propagationId;
  117       }
  118   
  119       /**
  120        * name of the property that changed.  May be null, if not known.
  121        * @serial
  122        */
  123       private String propertyName;
  124   
  125       /**
  126        * New value for property.  May be null if not known.
  127        * @serial
  128        */
  129       private Object newValue;
  130   
  131       /**
  132        * Previous value for property.  May be null if not known.
  133        * @serial
  134        */
  135       private Object oldValue;
  136   
  137       /**
  138        * Propagation ID.  May be null.
  139        * @serial
  140        * @see #getPropagationId
  141        */
  142       private Object propagationId;
  143   
  144       /**
  145        * Returns a string representation of the object.
  146        *
  147        * @return a string representation of the object
  148        *
  149        * @since 1.7
  150        */
  151       public String toString() {
  152           StringBuilder sb = new StringBuilder(getClass().getName());
  153           sb.append("[propertyName=").append(getPropertyName());
  154           appendTo(sb);
  155           sb.append("; oldValue=").append(getOldValue());
  156           sb.append("; newValue=").append(getNewValue());
  157           sb.append("; propagationId=").append(getPropagationId());
  158           sb.append("; source=").append(getSource());
  159           return sb.append("]").toString();
  160       }
  161   
  162       void appendTo(StringBuilder sb) {
  163       }
  164   }

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