160 lines
4.6 KiB
160 lines
4.6 KiB
/*
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* Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package java.awt.event;
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import java.awt.Container;
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import java.awt.Component;
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/**
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* A low-level event which indicates that a container's contents
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* changed because a component was added or removed.
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* <P>
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* Container events are provided for notification purposes ONLY;
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* The AWT will automatically handle changes to the containers
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* contents internally so that the program works properly regardless of
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* whether the program is receiving these events or not.
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* <P>
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* This low-level event is generated by a container object (such as a
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* Panel) when a component is added to it or removed from it.
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* The event is passed to every <code>ContainerListener</code>
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* or <code>ContainerAdapter</code> object which registered to receive such
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* events using the component's <code>addContainerListener</code> method.
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* (<code>ContainerAdapter</code> objects implement the
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* <code>ContainerListener</code> interface.) Each such listener object
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* gets this <code>ContainerEvent</code> when the event occurs.
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* <p>
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* An unspecified behavior will be caused if the {@code id} parameter
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* of any particular {@code ContainerEvent} instance is not
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* in the range from {@code CONTAINER_FIRST} to {@code CONTAINER_LAST}.
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*
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* @see ContainerAdapter
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* @see ContainerListener
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* @see <a href="https://docs.oracle.com/javase/tutorial/uiswing/events/containerlistener.html">Tutorial: Writing a Container Listener</a>
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*
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* @author Tim Prinzing
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* @author Amy Fowler
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* @since 1.1
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*/
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public class ContainerEvent extends ComponentEvent {
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/**
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* The first number in the range of ids used for container events.
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*/
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public static final int CONTAINER_FIRST = 300;
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/**
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* The last number in the range of ids used for container events.
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*/
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public static final int CONTAINER_LAST = 301;
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/**
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* This event indicates that a component was added to the container.
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*/
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public static final int COMPONENT_ADDED = CONTAINER_FIRST;
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/**
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* This event indicates that a component was removed from the container.
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*/
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public static final int COMPONENT_REMOVED = 1 + CONTAINER_FIRST;
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/**
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* The non-null component that is being added or
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* removed from the Container.
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*
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* @serial
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* @see #getChild()
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*/
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Component child;
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/*
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* JDK 1.1 serialVersionUID
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*/
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private static final long serialVersionUID = -4114942250539772041L;
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/**
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* Constructs a <code>ContainerEvent</code> object.
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* <p> This method throws an
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* <code>IllegalArgumentException</code> if <code>source</code>
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* is <code>null</code>.
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*
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* @param source The <code>Component</code> object (container)
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* that originated the event
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* @param id An integer indicating the type of event.
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* For information on allowable values, see
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* the class description for {@link ContainerEvent}
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* @param child the component that was added or removed
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* @throws IllegalArgumentException if <code>source</code> is null
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* @see #getContainer()
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* @see #getID()
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* @see #getChild()
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*/
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public ContainerEvent(Component source, int id, Component child) {
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super(source, id);
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this.child = child;
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}
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/**
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* Returns the originator of the event.
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*
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* @return the <code>Container</code> object that originated
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* the event, or <code>null</code> if the object is not a
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* <code>Container</code>.
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*/
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public Container getContainer() {
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return (source instanceof Container) ? (Container)source : null;
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}
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/**
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* Returns the component that was affected by the event.
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*
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* @return the Component object that was added or removed
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*/
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public Component getChild() {
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return child;
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}
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/**
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* Returns a parameter string identifying this event.
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* This method is useful for event-logging and for debugging.
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*
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* @return a string identifying the event and its attributes
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*/
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public String paramString() {
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String typeStr;
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switch(id) {
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case COMPONENT_ADDED:
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typeStr = "COMPONENT_ADDED";
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break;
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case COMPONENT_REMOVED:
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typeStr = "COMPONENT_REMOVED";
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break;
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default:
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typeStr = "unknown type";
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}
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return typeStr + ",child="+child.getName();
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}
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}
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