/*
* Copyright (c) 1996, 2007, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.awt.event;
import java.awt.Container;
import java.awt.Component;
/**
* A low-level event which indicates that a container's contents
* changed because a component was added or removed.
* <P>
* Container events are provided for notification purposes ONLY;
* The AWT will automatically handle changes to the containers
* contents internally so that the program works properly regardless of
* whether the program is receiving these events or not.
* <P>
* This low-level event is generated by a container object (such as a
* Panel) when a component is added to it or removed from it.
* The event is passed to every <code>ContainerListener</code>
* or <code>ContainerAdapter</code> object which registered to receive such
* events using the component's <code>addContainerListener</code> method.
* (<code>ContainerAdapter</code> objects implement the
* <code>ContainerListener</code> interface.) Each such listener object
* gets this <code>ContainerEvent</code> when the event occurs.
*
* @see ContainerAdapter
* @see ContainerListener
* @see <a href="http://java.sun.com/docs/books/tutorial/post1.0/ui/containerlistener.html">Tutorial: Writing a Container Listener</a>
*
* @author Tim Prinzing
* @author Amy Fowler
* @since 1.1
*/
public class ContainerEvent extends ComponentEvent {
/**
* The first number in the range of ids used for container events.
*/
public static final int CONTAINER_FIRST = 300;
/**
* The last number in the range of ids used for container events.
*/
public static final int CONTAINER_LAST = 301;
/**
* This event indicates that a component was added to the container.
*/
public static final int COMPONENT_ADDED = CONTAINER_FIRST;
/**
* This event indicates that a component was removed from the container.
*/
public static final int COMPONENT_REMOVED = 1 + CONTAINER_FIRST;
/**
* The non-null component that is being added or
* removed from the Container.
*
* @serial
* @see #getChild()
*/
Component child;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -4114942250539772041L;
/**
* Constructs a <code>ContainerEvent</code> object.
* <p>Note that passing in an invalid <code>id</code> results in
* unspecified behavior. This method throws an
* <code>IllegalArgumentException</code> if <code>source</code>
* is <code>null</code>.
*
* @param source the <code>Component</code> object (container)
* that originated the event
* @param id an integer indicating the type of event
* @param child the component that was added or removed
* @throws IllegalArgumentException if <code>source</code> is null
*/
public ContainerEvent(Component source, int id, Component child) {
super(source, id);
this.child = child;
}
/**
* Returns the originator of the event.
*
* @return the <code>Container</code> object that originated
* the event, or <code>null</code> if the object is not a
* <code>Container</code>.
*/
public Container getContainer() {
return (source instanceof Container) ? (Container)source : null;
}
/**
* Returns the component that was affected by the event.
*
* @return the Component object that was added or removed
*/
public Component getChild() {
return child;
}
/**
* Returns a parameter string identifying this event.
* This method is useful for event-logging and for debugging.
*
* @return a string identifying the event and its attributes
*/
public String paramString() {
String typeStr;
switch(id) {
case COMPONENT_ADDED:
typeStr = "COMPONENT_ADDED";
break;
case COMPONENT_REMOVED:
typeStr = "COMPONENT_REMOVED";
break;
default:
typeStr = "unknown type";
}
return typeStr + ",child="+child.getName();
}
}