/*
* 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.
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.
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 ContainerListener
or ContainerAdapter
object which registered to receive such
events using the component's addContainerListener
method.
(ContainerAdapter
objects implement the
ContainerListener
interface.) Each such listener object
gets this ContainerEvent
when the event occurs.
Author: Tim Prinzing, Amy Fowler See Also: - ContainerAdapter
- ContainerListener
- Tutorial: Writing a Container Listener
Since: 1.1
/**
* 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.
/**
* 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.
/**
* 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.
/**
* 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.
/**
* 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.
See Also: @serial
/**
* 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 ContainerEvent
object.
Note that passing in an invalid id
results in
unspecified behavior. This method throws an
IllegalArgumentException
if source
is null
.
Params: - source – the
Component
object (container)
that originated the event - id – an integer indicating the type of event
- child – the component that was added or removed
Throws: - IllegalArgumentException – if
source
is null
/**
* 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.
Returns: the Container
object that originated
the event, or null
if the object is not a
Container
.
/**
* 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.
Returns: the Component object that was added or removed
/**
* 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.
Returns: a string identifying the event and its attributes
/**
* 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();
}
}