/* 
 * This file is part of the Echo Web Application Framework (hereinafter "Echo").
 * Copyright (C) 2002-2009 NextApp, Inc.
 *
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 */

package nextapp.echo2.app.list;

import java.io.Serializable;

import nextapp.echo2.app.event.ListDataListener;

/**
 * A data model for list type components (SelectFields and ListBoxes).
 */
public interface ListModel
extends Serializable {

    /**
     * Adds a <code>ListDataListener</code> to the model.
     * <code>ListDataListener</code>s are notified whenever the model 
     * changes.
     *
     * @param l the <code>ListDataListener</code> to add
     */
    public void addListDataListener(ListDataListener l);

    /**
     * Returns the value at the specified index in the list.
     * 
     * @param index the index
     * @return the value
     */
    public Object get(int index);

    /**
     * Returns the size of the list.
     * 
     * @return the size
     */
    public int size();
    
    /**
     * Removes a <code>ListDataListener</code> from the model.
     * <code>ListDataListener</code> are notified whenever the model changes.
     *
     * @param l the <code>ListDataListener</code> to remove
     */
    public void removeListDataListener(ListDataListener l);
}