gcc/libjava/classpath/javax/swing/DefaultSingleSelectionModel.java

/* DefaultSingleSelectionModel.java --
   Copyright (C) 2002, 2004, 2006,  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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GNU Classpath is distributed in the hope that it will be useful, but
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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independent module, the terms and conditions of the license of that
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package javax.swing;

import java.io.Serializable;
import java.util.EventListener;

import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.EventListenerList;

/**
 * The default implementation of {@link SingleSelectionModel}, used in
 * {@link JTabbedPane}, {@link JMenuBar} and {@link JPopupMenu}.
 *
 * @author Andrew Selkirk
 */
public class DefaultSingleSelectionModel
  implements SingleSelectionModel, Serializable
{
  private static final long serialVersionUID = 3676229404753786004L;

  /**
   * changeEvent
   */
  protected transient ChangeEvent changeEvent;

  /**
   * listenerList
   */
  protected EventListenerList listenerList = new EventListenerList();

  /**
   * The selected index (or -1 for no selection).
   */
  private int index = -1;

  /**
   * Creates a new <code>DefaultSingleSelectionModel</code> with no current
   * selection.
   */
  public DefaultSingleSelectionModel()
  {
    // Do nothing.
  }

  /**
   * Returns the selected index or <code>-1</code> if there is no selection.
   * 
   * @return The selected index.
   * 
   * @see #setSelectedIndex(int)
   */
  public int getSelectedIndex()
  {
    return index;
  }

  /**
   * Sets the selected index and, if this is different to the previous 
   * selection, sends a {@link ChangeEvent} to all registered listeners.
   * 
   * @param index  the index (use <code>-1</code> to represent no selection).
   * 
   * @see #getSelectedIndex()
   * @see #clearSelection
   */
  public void setSelectedIndex(int index)
  {
    if (this.index != index)
      {
        this.index = index;
        fireStateChanged();
      }
  }

  /**
   * Clears the selection by setting the selected index to <code>-1</code> and
   * sends a {@link ChangeEvent} to all registered listeners.  If the selected
   * index is already <code>-1</code>, this method does nothing.  
   */
  public void clearSelection()
  {
    setSelectedIndex(-1);
  }

  /**
   * Returns <code>true</code> if there is a selection, and <code>false</code>
   * otherwise.  
   * 
   * @return A boolean.
   */
  public boolean isSelected()
  {
    return index != -1;
  }

  /**
   * Registers a listener to receive {@link ChangeEvent} notifications from
   * this model whenever the selected index changes.
   *
   * @param listener the listener to add.
   */
  public void addChangeListener(ChangeListener listener)
  {
    listenerList.add(ChangeListener.class, listener);
  }

  /**
   * Deregisters a listener so that it no longer receives {@link ChangeEvent}
   * notifications from this model.
   *
   * @param listener the listener to remove.
   */
  public void removeChangeListener(ChangeListener listener)
  {
    listenerList.remove(ChangeListener.class, listener);
  }

  /**
   * fireStateChanged
   */
  protected void fireStateChanged()
  {
    if (changeEvent == null)
      changeEvent = new ChangeEvent(this);
    ChangeListener[] listeners = getChangeListeners();
    for (int i = 0; i < listeners.length; i++)
      listeners[i].stateChanged(changeEvent);
  }

  /**
   * getListeners
   *
   * @param listenerClass the type fo listener
   *
   * @return an array of listeners
   *
   * @since 1.3
   */
  public <T extends EventListener> T[] getListeners(Class<T> listenerClass)
  {
    return listenerList.getListeners(listenerClass);
  }

  /**
   * getChangeListeners
   *
   * @since 1.4
   */
  public ChangeListener[] getChangeListeners()
  {
    return (ChangeListener[]) getListeners(ChangeListener.class);
  }
}