001    /* FocusEvent.java -- generated for a focus change
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    
011    GNU Classpath is distributed in the hope that it will be useful, but
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    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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
032    module.  An independent module is a module which is not derived from
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.Component;
042    
043    /**
044     * This class represents an event generated when a focus change occurs for a
045     * component. There are both temporary changes, such as when focus is stolen
046     * during a sroll then returned, and permanent changes, such as when the user
047     * TABs through focusable components.
048     *
049     * @author Aaron M. Renn (arenn@urbanophile.com)
050     * @see FocusAdapter
051     * @see FocusListener
052     * @since 1.1
053     * @status updated to 1.4
054     */
055    public class FocusEvent extends ComponentEvent
056    {
057      /**
058       * Compatible with JDK 1.1+.
059       */
060      private static final long serialVersionUID = 523753786457416396L;
061    
062      /** This is the first id in the range of ids used by this class. */
063      public static final int FOCUS_FIRST = 1004;
064    
065      /** This is the last id in the range of ids used by this class. */
066      public static final int FOCUS_LAST = 1005;
067    
068      /** This is the event id for a focus gained event. */
069      public static final int FOCUS_GAINED = 1004;
070    
071      /** This is the event id for a focus lost event. */
072      public static final int FOCUS_LOST = 1005;
073    
074      /**
075       * Indicates whether or not the focus change is temporary.
076       *
077       * @see #isTemporary()
078       * @serial true if the focus change is temporary
079       */
080      private final boolean temporary;
081    
082      /**
083       * The other component which is giving up or stealing focus from this
084       * component, if known.
085       *
086       * @see #getOppositeComponent()
087       * @serial the component with the opposite focus event, or null
088       * @since 1.4
089       */
090      private final Component opposite;
091    
092      /**
093       * Initializes a new instance of <code>FocusEvent</code> with the
094       * specified source, id, temporary status, and opposite counterpart. Note
095       * that an invalid id leads to unspecified results.
096       *
097       * @param source the component that is gaining or losing focus
098       * @param id the event id
099       * @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