001    /* ContainerEvent.java -- components added/removed from a container
002       Copyright (C) 1999, 2002, 2005  Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package java.awt.event;
040    
041    import java.awt.Component;
042    import java.awt.Container;
043    
044    /**
045     * This event is generated when a component is added or removed from a
046     * container.  Applications do not ordinarily need to handle these events
047     * since the AWT system handles them internally.
048     *
049     * @author Aaron M. Renn (arenn@urbanophile.com)
050     * @see ContainerAdapter
051     * @see ContainerListener
052     * @since 1.1
053     * @status updated to 1.4
054     */
055    public class ContainerEvent extends ComponentEvent
056    {
057      /**
058       * Compatible with JDK 1.1+.
059       */
060      private static final long serialVersionUID = -4114942250539772041L;
061    
062      /** This is the first id in the id range used by this class. */
063      public static final int CONTAINER_FIRST = 300;
064    
065      /** This is the last id in the id range used by this class. */
066      public static final int CONTAINER_LAST = 301;
067    
068      /** This id indicates a component was added to the container. */
069      public static final int COMPONENT_ADDED = 300;
070    
071      /** This id indicates a component was removed from the container. */
072      public static final int COMPONENT_REMOVED = 301;
073    
074      /**
075       * The non-null child component that was added or removed.
076       *
077       * @serial the child component that changed
078       */
079      private final Component child;
080    
081      /**
082       * Initializes a new instance of <code>ContainerEvent</code> with the
083       * specified source and id.  Additionally, the affected child component
084       * is also passed as a parameter. Note that an invalid id leads to
085       * unspecified results.
086       *
087       * @param source the source container of the event
088       * @param id the event id
089       * @param child the child component affected by this event
090       * @throws IllegalArgumentException if source is null
091       */
092      public ContainerEvent(Component source, int id, Component child)
093      {
094        super(source, id);
095        this.child = child;
096      }
097    
098      /**
099       * Returns the source of this event as a <code>Container</code>.
100       *
101       * @return the source of the event
102       * @throws ClassCastException if the source is changed to a non-Container
103       */
104      public Container getContainer()
105      {
106        return (Container) source;
107      }
108    
109      /**
110       * This method returns the child object that was added or removed from
111       * the container.
112       *
113       * @return the child object added or removed
114       */
115      public Component getChild()
116      {
117        return child;
118      }
119    
120      /**
121       * This method returns a string identifying this event. It is formatted as:
122       * <code>(getID() == COMPONENT_ADDED ? "COMPONENT_ADDED"
123       * : "COMPONENT_REMOVED") + ",child=" + getChild().getName()</code>.
124       *
125       * @return a string identifying this event
126       */
127      public String paramString()
128      {
129        // Unlike Sun, we don't throw NullPointerException if child is illegally
130        // null.
131        return (id == COMPONENT_ADDED ? "COMPONENT_ADDED,child="
132                : id == COMPONENT_REMOVED ? "COMPONENT_REMOVED,child="
133                : "unknown type,child=") + (child == null ? "" : child.getName());
134      }
135    } // class ContainerEvent