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

This file is part of GNU Classpath.

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permission to link this library with independent modules to produce an
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package javax.swing;

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

/**
 * A data model that is used in components that support at most one
 * selected element, like {@link JTabbedPane}, {@link JMenu} and
 * {@link JPopupMenu}.
 *
 * @author Andrew Selkirk
 */
public interface SingleSelectionModel
{
  /**
   * Returns the selected index or <code>-1</code> if there is no selection.
   *
   * @return The selected index.
   *
   * @see #setSelectedIndex(int)
   */
  int getSelectedIndex();

  /**
   * 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
   */
  void setSelectedIndex(int index);

  /**
   * 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.
   */
  void clearSelection();

  /**
   * Returns <code>true</code> if there is a selection, and <code>false</code>
   * otherwise.
   *
   * @return A boolean.
   */
  boolean isSelected();

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

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

}