https://openjdk.java.net/ 
/*
 * 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.AWTEvent;
import java.awt.ItemSelectable;


A semantic event which indicates that an item was selected or deselected.
This high-level event is generated by an ItemSelectable object (such as a
List) when an item is selected or deselected by the user.
The event is passed to every ItemListener object which
registered to receive such events using the component's
addItemListener method.


The object that implements the ItemListener interface gets
this ItemEvent when the event occurs. The listener is
spared the details of processing individual mouse movements and mouse
clicks, and can instead process a "meaningful" (semantic) event like
"item selected" or "item deselected".

Author:Carl Quinn
See Also:
Since:1.1
/**
 * A semantic event which indicates that an item was selected or deselected.
 * This high-level event is generated by an ItemSelectable object (such as a
 * List) when an item is selected or deselected by the user.
 * The event is passed to every <code>ItemListener</code> object which
 * registered to receive such events using the component's
 * <code>addItemListener</code> method.
 * <P>
 * The object that implements the <code>ItemListener</code> interface gets
 * this <code>ItemEvent</code> when the event occurs. The listener is
 * spared the details of processing individual mouse movements and mouse
 * clicks, and can instead process a "meaningful" (semantic) event like
 * "item selected" or "item deselected".
 *
 * @author Carl Quinn
 *
 * @see java.awt.ItemSelectable
 * @see ItemListener
 * @see <a href="http://java.sun.com/docs/books/tutorial/post1.0/ui/itemlistener.html">Tutorial: Writing an Item Listener</a>
 *
 * @since 1.1
 */
public class ItemEvent extends AWTEvent {

    
The first number in the range of ids used for item events.

/**
     * The first number in the range of ids used for item events.
     */
    public static final int ITEM_FIRST          = 701;

    
The last number in the range of ids used for item events.

/**
     * The last number in the range of ids used for item events.
     */
    public static final int ITEM_LAST           = 701;

    
This event id indicates that an item's state changed.

/**
     * This event id indicates that an item's state changed.
     */
    public static final int ITEM_STATE_CHANGED  = ITEM_FIRST; //Event.LIST_SELECT

    
This state-change value indicates that an item was selected.

/**
     * This state-change value indicates that an item was selected.
     */
    public static final int SELECTED = 1;

    
This state-change-value indicates that a selected item was deselected.

/**
     * This state-change-value indicates that a selected item was deselected.
     */
    public static final int DESELECTED  = 2;

    
The item whose selection state has changed.

See Also:
@serial
/**
     * The item whose selection state has changed.
     *
     * @serial
     * @see #getItem()
     */
    Object item;

    
stateChange indicates whether the item
was selected or deselected.

See Also:
@serial
/**
     * <code>stateChange</code> indicates whether the <code>item</code>
     * was selected or deselected.
     *
     * @serial
     * @see #getStateChange()
     */
    int stateChange;

    /*
     * JDK 1.1 serialVersionUID
     */
    private static final long serialVersionUID = -608708132447206933L;

    
Constructs an ItemEvent object.

Note that passing in an invalid id results in
unspecified behavior. This method throws an
IllegalArgumentException if source
is null.

Params:
  • source – the ItemSelectable object
              that originated the event
  • id –     an integer that identifies the event type
  • item –   an object -- the item affected by the event
  • stateChange – 
              an integer that indicates whether the item was
              selected or deselected
Throws:
/**
     * Constructs an <code>ItemEvent</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>ItemSelectable</code> object
     *               that originated the event
     * @param id     an integer that identifies the event type
     * @param item   an object -- the item affected by the event
     * @param stateChange
     *               an integer that indicates whether the item was
     *               selected or deselected
     * @throws IllegalArgumentException if <code>source</code> is null
     */
    public ItemEvent(ItemSelectable source, int id, Object item, int stateChange) {
        super(source, id);
        this.item = item;
        this.stateChange = stateChange;
    }

    
Returns the originator of the event.

Returns:the ItemSelectable object that originated the event.
/**
     * Returns the originator of the event.
     *
     * @return the ItemSelectable object that originated the event.
     */
    public ItemSelectable getItemSelectable() {
        return (ItemSelectable)source;
    }

   
Returns the item affected by the event.

Returns:the item (object) that was affected by the event
/**
    * Returns the item affected by the event.
    *
    * @return the item (object) that was affected by the event
    */
    public Object getItem() {
        return item;
    }

   
Returns the type of state change (selected or deselected).

See Also:
Returns:an integer that indicates whether the item was selected
        or deselected
/**
    * Returns the type of state change (selected or deselected).
    *
    * @return an integer that indicates whether the item was selected
    *         or deselected
    *
    * @see #SELECTED
    * @see #DESELECTED
    */
    public int getStateChange() {
        return stateChange;
    }

    
Returns a parameter string identifying this item 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 item 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 ITEM_STATE_CHANGED:
              typeStr = "ITEM_STATE_CHANGED";
              break;
          default:
              typeStr = "unknown type";
        }

        String stateStr;
        switch(stateChange) {
          case SELECTED:
              stateStr = "SELECTED";
              break;
          case DESELECTED:
              stateStr = "DESELECTED";
              break;
          default:
              stateStr = "unknown type";
        }
        return typeStr + ",item="+item + ",stateChange="+stateStr;
    }

}