J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1996-2007 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.awt.event; |
| 27 | |
| 28 | import java.awt.Container; |
| 29 | import java.awt.Component; |
| 30 | |
| 31 | /** |
| 32 | * A low-level event which indicates that a container's contents |
| 33 | * changed because a component was added or removed. |
| 34 | * <P> |
| 35 | * Container events are provided for notification purposes ONLY; |
| 36 | * The AWT will automatically handle changes to the containers |
| 37 | * contents internally so that the program works properly regardless of |
| 38 | * whether the program is receiving these events or not. |
| 39 | * <P> |
| 40 | * This low-level event is generated by a container object (such as a |
| 41 | * Panel) when a component is added to it or removed from it. |
| 42 | * The event is passed to every <code>ContainerListener</code> |
| 43 | * or <code>ContainerAdapter</code> object which registered to receive such |
| 44 | * events using the component's <code>addContainerListener</code> method. |
| 45 | * (<code>ContainerAdapter</code> objects implement the |
| 46 | * <code>ContainerListener</code> interface.) Each such listener object |
| 47 | * gets this <code>ContainerEvent</code> when the event occurs. |
| 48 | * |
| 49 | * @see ContainerAdapter |
| 50 | * @see ContainerListener |
| 51 | * @see <a href="http://java.sun.com/docs/books/tutorial/post1.0/ui/containerlistener.html">Tutorial: Writing a Container Listener</a> |
| 52 | * |
| 53 | * @author Tim Prinzing |
| 54 | * @author Amy Fowler |
| 55 | * @since 1.1 |
| 56 | */ |
| 57 | public class ContainerEvent extends ComponentEvent { |
| 58 | |
| 59 | /** |
| 60 | * The first number in the range of ids used for container events. |
| 61 | */ |
| 62 | public static final int CONTAINER_FIRST = 300; |
| 63 | |
| 64 | /** |
| 65 | * The last number in the range of ids used for container events. |
| 66 | */ |
| 67 | public static final int CONTAINER_LAST = 301; |
| 68 | |
| 69 | /** |
| 70 | * This event indicates that a component was added to the container. |
| 71 | */ |
| 72 | public static final int COMPONENT_ADDED = CONTAINER_FIRST; |
| 73 | |
| 74 | /** |
| 75 | * This event indicates that a component was removed from the container. |
| 76 | */ |
| 77 | public static final int COMPONENT_REMOVED = 1 + CONTAINER_FIRST; |
| 78 | |
| 79 | /** |
| 80 | * The non-null component that is being added or |
| 81 | * removed from the Container. |
| 82 | * |
| 83 | * @serial |
| 84 | * @see #getChild() |
| 85 | */ |
| 86 | Component child; |
| 87 | |
| 88 | /* |
| 89 | * JDK 1.1 serialVersionUID |
| 90 | */ |
| 91 | private static final long serialVersionUID = -4114942250539772041L; |
| 92 | |
| 93 | /** |
| 94 | * Constructs a <code>ContainerEvent</code> object. |
| 95 | * <p>Note that passing in an invalid <code>id</code> results in |
| 96 | * unspecified behavior. This method throws an |
| 97 | * <code>IllegalArgumentException</code> if <code>source</code> |
| 98 | * is <code>null</code>. |
| 99 | * |
| 100 | * @param source the <code>Component</code> object (container) |
| 101 | * that originated the event |
| 102 | * @param id an integer indicating the type of event |
| 103 | * @param child the component that was added or removed |
| 104 | * @throws IllegalArgumentException if <code>source</code> is null |
| 105 | */ |
| 106 | public ContainerEvent(Component source, int id, Component child) { |
| 107 | super(source, id); |
| 108 | this.child = child; |
| 109 | } |
| 110 | |
| 111 | /** |
| 112 | * Returns the originator of the event. |
| 113 | * |
| 114 | * @return the <code>Container</code> object that originated |
| 115 | * the event, or <code>null</code> if the object is not a |
| 116 | * <code>Container</code>. |
| 117 | */ |
| 118 | public Container getContainer() { |
| 119 | return (source instanceof Container) ? (Container)source : null; |
| 120 | } |
| 121 | |
| 122 | /** |
| 123 | * Returns the component that was affected by the event. |
| 124 | * |
| 125 | * @return the Component object that was added or removed |
| 126 | */ |
| 127 | public Component getChild() { |
| 128 | return child; |
| 129 | } |
| 130 | |
| 131 | /** |
| 132 | * Returns a parameter string identifying this event. |
| 133 | * This method is useful for event-logging and for debugging. |
| 134 | * |
| 135 | * @return a string identifying the event and its attributes |
| 136 | */ |
| 137 | public String paramString() { |
| 138 | String typeStr; |
| 139 | switch(id) { |
| 140 | case COMPONENT_ADDED: |
| 141 | typeStr = "COMPONENT_ADDED"; |
| 142 | break; |
| 143 | case COMPONENT_REMOVED: |
| 144 | typeStr = "COMPONENT_REMOVED"; |
| 145 | break; |
| 146 | default: |
| 147 | typeStr = "unknown type"; |
| 148 | } |
| 149 | return typeStr + ",child="+child.getName(); |
| 150 | } |
| 151 | } |