1 /*
   2  * Copyright (c) 1999, 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.awt.event;
  27 
  28 import java.util.EventListener;
  29 
  30 /**
  31  * The listener interface for receiving hierarchy changed events.
  32  * The class that is interested in processing a hierarchy changed event
  33  * should implement this interface.
  34  * The listener object created from that class is then registered with a
  35  * Component using the Component's <code>addHierarchyListener</code>
  36  * method. When the hierarchy to which the Component belongs changes, the
  37  * <code>hierarchyChanged</code> method in the listener object is invoked,
  38  * and the <code>HierarchyEvent</code> is passed to it.
  39  * <p>
  40  * Hierarchy events are provided for notification purposes ONLY;
  41  * The AWT will automatically handle changes to the hierarchy internally so
  42  * that GUI layout, displayability, and visibility work properly regardless
  43  * of whether a program registers a <code>HierarchyListener</code> or not.
  44  *
  45  * @author      David Mendenhall
  46  * @see         HierarchyEvent
  47  * @since       1.3
  48  */
  49 public interface HierarchyListener extends EventListener {
  50     /**
  51      * Called when the hierarchy has been changed. To discern the actual
  52      * type of change, call <code>HierarchyEvent.getChangeFlags()</code>.
  53      *
  54      * @see HierarchyEvent#getChangeFlags()
  55      */
  56     public void hierarchyChanged(HierarchyEvent e);
  57 }