001 /* ItemEvent.java -- event for item state changes
002 Copyright (C) 1999, 2002, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
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012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
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017 along with GNU Classpath; see the file COPYING. If not, write to the
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019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
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033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt.event;
040
041 import java.awt.AWTEvent;
042 import java.awt.ItemSelectable;
043
044 /**
045 * This event is generated when a selection item changes state. This is an
046 * abstraction that distills a large number of individual mouse or keyboard
047 * events into a simpler "item selected" and "item deselected" events.
048 *
049 * @author Aaron M. Renn (arenn@urbanophile.com)
050 * @see ItemSelectable
051 * @see ItemListener
052 * @since 1.1
053 * @status updated to 1.4
054 */
055 public class ItemEvent extends AWTEvent
056 {
057 /**
058 * Compatible with JDK 1.1+.
059 */
060 private static final long serialVersionUID = -608708132447206933L;
061
062 /** This is the first id in the event id range used by this class. */
063 public static final int ITEM_FIRST = 701;
064
065 /** This is the last id in the event id range used by this class. */
066 public static final int ITEM_LAST = 701;
067
068 /** This event id indicates a state change occurred. */
069 public static final int ITEM_STATE_CHANGED = 701;
070
071 /** This type indicates that the item was selected. */
072 public static final int SELECTED = 1;
073
074 /** This type indicates that the item was deselected. */
075 public static final int DESELECTED = 2;
076
077 /**
078 * The item affected by this event.
079 *
080 * @serial the item of the selection
081 */
082 private final Object item;
083
084 /**
085 * The state change direction, one of {@link #SELECTED} or
086 * {@link #DESELECTED}.
087 *
088 * @serial the selection state
089 */
090 private final int stateChange;
091
092 /**
093 * Initializes a new instance of <code>ItemEvent</code> with the specified
094 * source, id, and state change constant. Note that an invalid id leads to
095 * unspecified results.
096 *
097 * @param source the source of the event
098 * @param id the event id
099 * @param item the item affected by the state change
100 * @param stateChange one of {@link #SELECTED} or {@link #DESELECTED}
101 */
102 public ItemEvent(ItemSelectable source, int id, Object item, int stateChange)
103 {
104 super(source, id);
105 this.item = item;
106 this.stateChange = stateChange;
107 }
108
109 /**
110 * This method returns the event source as an <code>ItemSelectable</code>.
111 *
112 * @return the event source as an <code>ItemSelected</code>
113 * @throws ClassCastException if source is changed to a non-ItemSelectable
114 */
115 public ItemSelectable getItemSelectable()
116 {
117 return (ItemSelectable) source;
118 }
119
120 /**
121 * Returns the item affected by this state change.
122 *
123 * @return the item affected by this state change
124 */
125 public Object getItem()
126 {
127 return item;
128 }
129
130 /**
131 * Returns the type of state change, either {@link #SELECTED} or
132 * {@link #DESELECTED}.
133 *
134 * @return the type of state change
135 */
136 public int getStateChange()
137 {
138 return stateChange;
139 }
140
141 /**
142 * Returns a string identifying this event. This is in the format:
143 * <code>"ITEM_STATE_CHANGED,item=" + item + ",stateChange="
144 * + (getStateChange() == DESELECTED ? "DESELECTED" : "SELECTED")</code>.
145 *
146 * @return a string identifying this event
147 */
148 public String paramString()
149 {
150 return (id == ITEM_STATE_CHANGED ? "ITEM_STATE_CHANGED,item="
151 : "unknown type,item=") + item + ",stateChange="
152 + (stateChange == SELECTED ? "SELECTED"
153 : stateChange == DESELECTED ? "DESELECTED" : "unknown type");
154 }
155 } // class ItemEvent