001    /* SingleSelectionModel.java --
002       Copyright (C) 2002, 2004 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    package javax.swing;
039    
040    import javax.swing.event.ChangeEvent;
041    import javax.swing.event.ChangeListener;
042    
043    /**
044     * A data model that is used in components that support at most one
045     * selected element, like {@link JTabbedPane}, {@link JMenu} and
046     * {@link JPopupMenu}.
047     *
048     * @author Andrew Selkirk
049     */
050    public interface SingleSelectionModel
051    {
052      /**
053       * Returns the selected index or <code>-1</code> if there is no selection.
054       *
055       * @return The selected index.
056       *
057       * @see #setSelectedIndex(int)
058       */
059      int getSelectedIndex();
060    
061      /**
062       * Sets the selected index and, if this is different to the previous
063       * selection, sends a {@link ChangeEvent} to all registered listeners.
064       *
065       * @param index  the index (use <code>-1</code> to represent no selection).
066       *
067       * @see #getSelectedIndex()
068       * @see #clearSelection
069       */
070      void setSelectedIndex(int index);
071    
072      /**
073       * Clears the selection by setting the selected index to <code>-1</code> and
074       * sends a {@link ChangeEvent} to all registered listeners.  If the selected
075       * index is already <code>-1</code>, this method does nothing.
076       */
077      void clearSelection();
078    
079      /**
080       * Returns <code>true</code> if there is a selection, and <code>false</code>
081       * otherwise.
082       *
083       * @return A boolean.
084       */
085      boolean isSelected();
086    
087      /**
088       * Registers a listener to receive {@link ChangeEvent} notifications from
089       * this model whenever the selected index changes.
090       *
091       * @param listener the listener to add.
092       */
093      void addChangeListener(ChangeListener listener);
094    
095      /**
096       * Deregisters a listener so that it no longer receives {@link ChangeEvent}
097       * notifications from this model.
098       *
099       * @param listener the listener to remove.
100       */
101      void removeChangeListener(ChangeListener listener);
102    
103    }