libjava/java/awt/event/ItemEvent.java

   1 /* ItemEvent.java -- event for item state changes
   2    Copyright (C) 1999, 2002, 2005  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.awt.event;
  40
  41 import java.awt.AWTEvent;
  42 import java.awt.ItemSelectable;
  43
  44 /**
  45  * This event is generated when a selection item changes state. This is an
  46  * abstraction that distills a large number of individual mouse or keyboard
  47  * events into a simpler "item selected" and "item deselected" events.
  48  *
  49  * @author Aaron M. Renn (arenn@urbanophile.com)
  50  * @see ItemSelectable
  51  * @see ItemListener
  52  * @since 1.1
  53  * @status updated to 1.4
  54  */
  55 public class ItemEvent extends AWTEvent
  56 {
  57   /**
  58    * Compatible with JDK 1.1+.
  59    */
  60   private static final long serialVersionUID = -608708132447206933L;
  61
  62   /** This is the first id in the event id range used by this class. */
  63   public static final int ITEM_FIRST = 701;
  64
  65   /** This is the last id in the event id range used by this class. */
  66   public static final int ITEM_LAST = 701;
  67
  68   /** This event id indicates a state change occurred. */
  69   public static final int ITEM_STATE_CHANGED = 701;
  70
  71   /** This type indicates that the item was selected. */
  72   public static final int SELECTED = 1;
  73
  74   /** This type indicates that the item was deselected. */
  75   public static final int DESELECTED = 2;
  76
  77   /**
  78    * The item affected by this event.
  79    *
  80    * @serial the item of the selection
  81    */
  82   private final Object item;
  83
  84   /**
  85    * The state change direction, one of {@link #SELECTED} or
  86    * {@link #DESELECTED}.
  87    *
  88    * @serial the selection state
  89    */
  90   private final int stateChange;
  91
  92   /**
  93    * Initializes a new instance of <code>ItemEvent</code> with the specified
  94    * source, id, and state change constant. Note that an invalid id leads to
  95    * unspecified results.
  96    *
  97    * @param source the source of the event
  98    * @param id the event id
  99    * @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