/* FocusTraversalPolicy.java -- 
   Copyright (C) 2002 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
the Free Software Foundation; either version 2, or (at your option)
any later version.

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General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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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
executable, regardless of the license terms of these independent
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exception statement from your version. */


package java.awt;

/**
 * @since 1.4
 */
public abstract class FocusTraversalPolicy
{
  /**
   * Creates a <code>FocusTraversalPolicy</code> object.
   */
  public FocusTraversalPolicy()
  {
    // Do nothing in here.
  }

  /**
   * Returns the Component that should receive the focus after a Component.
   *
   * @exception IllegalArgumentException If root or current is null,
   * or if root is not a focus cycle root of current.
   */
  public abstract Component getComponentAfter(Container root,
                                              Component current);

  /**
   * Returns the Component that should receive the focus before a Component.
   *
   * @exception IllegalArgumentException If root or current is null,
   * or if root is not a focus cycle root of current.
   */
  public abstract Component getComponentBefore(Container root,
                                               Component current);

  /**
   * Returns the first Component in the traversal cycle.
   *
   * @exception IllegalArgumentException If root is null.
   */
  public abstract Component getFirstComponent(Container root);

  /**
   * Returns the last Component in the traversal cycle.
   *
   * @exception IllegalArgumentException If root is null.
   */
  public abstract Component getLastComponent(Container root);

  /**
   * Returns the default Component to focus.
   *
   * @exception IllegalArgumentException If root is null.
   */
  public abstract Component getDefaultComponent(Container root);

  /**
   * Returns the Component that should receive the focus when a Window is made
   * visible for the first time.
   *
   * @exception IllegalArgumentException If window is null.
   */
  public Component getInitialComponent(Window window)
  {
    return getDefaultComponent(window);
  }
} // class FocusTraversalPolicy
