001/* ItemEvent.java -- event for item state changes
002   Copyright (C) 1999, 2002, 2005  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.awt.event;
040
041import java.awt.AWTEvent;
042import 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 */
055public 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