libjava/java/awt/event/FocusEvent.java

   1 /* FocusEvent.java -- generated for a focus change
   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.Component;
  42
  43 /**
  44  * This class represents an event generated when a focus change occurs for a
  45  * component. There are both temporary changes, such as when focus is stolen
  46  * during a sroll then returned, and permanent changes, such as when the user
  47  * TABs through focusable components.
  48  *
  49  * @author Aaron M. Renn (arenn@urbanophile.com)
  50  * @see FocusAdapter
  51  * @see FocusListener
  52  * @since 1.1
  53  * @status updated to 1.4
  54  */
  55 public class FocusEvent extends ComponentEvent
  56 {
  57   /**
  58    * Compatible with JDK 1.1+.
  59    */
  60   private static final long serialVersionUID = 523753786457416396L;
  61
  62   /** This is the first id in the range of ids used by this class. */
  63   public static final int FOCUS_FIRST = 1004;
  64
  65   /** This is the last id in the range of ids used by this class. */
  66   public static final int FOCUS_LAST = 1005;
  67
  68   /** This is the event id for a focus gained event. */
  69   public static final int FOCUS_GAINED = 1004;
  70
  71   /** This is the event id for a focus lost event. */
  72   public static final int FOCUS_LOST = 1005;
  73
  74   /**
  75    * Indicates whether or not the focus change is temporary.
  76    *
  77    * @see #isTemporary()
  78    * @serial true if the focus change is temporary
  79    */
  80   private final boolean temporary;
  81
  82   /**
  83    * The other component which is giving up or stealing focus from this
  84    * component, if known.
  85    *
  86    * @see #getOppositeComponent()
  87    * @serial the component with the opposite focus event, or null
  88    * @since 1.4
  89    */
  90   private final Component opposite;
  91
  92   /**
  93    * Initializes a new instance of <code>FocusEvent</code> with the
  94    * specified source, id, temporary status, and opposite counterpart. Note
  95    * that an invalid id leads to unspecified results.
  96    *
  97    * @param source the component that is gaining or losing focus
  98    * @param id the event id
  99    * @param temporary true if the focus change is temporary
 100    * @param opposite the component receiving the opposite focus event, or null
 101    * @throws IllegalArgumentException if source is null
 102    */
 103   public FocusEvent(Component source, int id, boolean temporary,
 104                     Component opposite)
 105   {
 106     super(source, id);
 107     this.temporary = temporary;
 108     this.opposite = opposite;
 109   }
 110
 111   /**
 112    * Initializes a new instance of <code>FocusEvent</code> with the
 113    * specified source, id, and temporary status. Note that an invalid id
 114    * leads to unspecified results.
 115    *
 116    * @param source the component that is gaining or losing focus
 117    * @param id the event id
 118    * @param temporary true if the focus change is temporary
 119    * @throws IllegalArgumentException if source is null
 120    */
 121   public FocusEvent(Component source, int id, boolean temporary)
 122   {
 123     this(source, id, temporary, null);
 124   }
 125
 126   /**
 127    * Initializes a new instance of <code>FocusEvent</code> with the
 128    * specified source and id. Note that an invalid id leads to unspecified
 129    * results.
 130    *
 131    * @param source the component that is gaining or losing focus
 132    * @param id the event id
 133    * @throws IllegalArgumentException if source is null
 134    */
 135   public FocusEvent(Component source, int id)
 136   {
 137     this(source, id, false, null);
 138   }
 139
 140   /**
 141    * This method tests whether or not the focus change is temporary or
 142    * permanent.
 143    *
 144    * @return true if the focus change is temporary
 145    */
 146   public boolean isTemporary()
 147   {
 148     return temporary;
 149   }
 150
 151   /**
 152    * Returns the component which received the opposite focus event. If this
 153    * component gained focus, the opposite lost focus; likewise if this
 154    * component is giving up focus, the opposite is gaining it. If this
 155    * information is unknown, perhaps because the opposite is a native
 156    * application, this returns null.
 157    *
 158    * @return the component with the focus opposite, or null
 159    * @since 1.4
 160    */
 161   public Component getOppositeComponent()
 162   {
 163     return opposite;
 164   }
 165
 166   /**
 167    * Returns a string identifying this event. This is formatted as:
 168    * <code>(getID() == FOCUS_GAINED ? "FOCUS_GAINED" : "FOCUS_LOST")
 169    * + (isTemporary() ? ",temporary," : ",permanent,") + "opposite="
 170    * + getOppositeComponent()</code>.
 171    *
 172    * @return a string identifying this event
 173    */
 174   public String paramString()
 175   {
 176     return (id == FOCUS_GAINED ? "FOCUS_GAINED"
 177             : id == FOCUS_LOST ? "FOCUS_LOST" : "unknown type")
 178       + (temporary ? ",temporary,opposite=" : ",permanent,opposite=")
 179       + opposite;
 180   }
 181 } // class FocusEvent