001/* FocusTraversalPolicy.java --
002   Copyright (C) 2002 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.awt;
040
041/**
042 * @since 1.4
043 */
044public abstract class FocusTraversalPolicy
045{
046  /**
047   * Creates a <code>FocusTraversalPolicy</code> object.
048   */
049  public FocusTraversalPolicy()
050  {
051    // Do nothing in here.
052  }
053
054  /**
055   * Returns the Component that should receive the focus after a Component.
056   *
057   * @exception IllegalArgumentException If root or current is null,
058   * or if root is not a focus cycle root of current.
059   */
060  public abstract Component getComponentAfter(Container root,
061                                              Component current);
062
063  /**
064   * Returns the Component that should receive the focus before a Component.
065   *
066   * @exception IllegalArgumentException If root or current is null,
067   * or if root is not a focus cycle root of current.
068   */
069  public abstract Component getComponentBefore(Container root,
070                                               Component current);
071
072  /**
073   * Returns the first Component in the traversal cycle.
074   *
075   * @exception IllegalArgumentException If root is null.
076   */
077  public abstract Component getFirstComponent(Container root);
078
079  /**
080   * Returns the last Component in the traversal cycle.
081   *
082   * @exception IllegalArgumentException If root is null.
083   */
084  public abstract Component getLastComponent(Container root);
085
086  /**
087   * Returns the default Component to focus.
088   *
089   * @exception IllegalArgumentException If root is null.
090   */
091  public abstract Component getDefaultComponent(Container root);
092
093  /**
094   * Returns the Component that should receive the focus when a Window is made
095   * visible for the first time.
096   *
097   * @exception IllegalArgumentException If window is null.
098   */
099  public Component getInitialComponent(Window window)
100  {
101    return getDefaultComponent(window);
102  }
103} // class FocusTraversalPolicy