/*

 * Copyright 2000-2002 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package javax.swing;

import java.awt.event.*;

import javax.swing.event.*;

/**

 * A model for a potentially unbounded sequence of object values.  This model

 * is similar to <code>ListModel</code> however there are some important differences:

 * <ul>

 * <li> The number of sequence elements isn't neccessarily bounded.

 * <li> The model doesn't support indexed random access to sequence elements.

 *      Only three sequence values are accessible at a time: current, next and

 *      previous.

 * <li> The current sequence element, can be set.

 * </ul>

 * <p>

 * A <code>SpinnerModel</code> has three properties, only the first is read/write.

 * <dl>

 *   <dt><code>value</code>

 *   <dd>The current element of the sequence.

 *

 *   <dt><code>nextValue</code>

 *   <dd>The following element or null if <code>value</code> is the

 *     last element of the sequence.

 *

 *   <dt><code>previousValue</code>

 *   <dd>The preceeding element or null if <code>value</code> is the

 *     first element of the sequence.

 * </dl>

 * When the the <code>value</code> property changes,

 * <code>ChangeListeners</code> are notified.  <code>SpinnerModel</code> may

 * choose to notify the <code>ChangeListeners</code> under other circumstances.

 *

 * @see JSpinner

 * @see AbstractSpinnerModel

 * @see SpinnerListModel

 * @see SpinnerNumberModel

 * @see SpinnerDateModel

 *

 * @author Hans Muller

 * @since 1.4

 */

public interface SpinnerModel

{

    /**

     * The <i>current element</i> of the sequence.  This element is usually

     * displayed by the <code>editor</code> part of a <code>JSpinner</code>.

     *

     * @return the current spinner value.

     * @see #setValue

     */

    Object getValue();

    /**

     * Changes current value of the model, typically this value is displayed

     * by the <code>editor</code> part of a  <code>JSpinner</code>.

     * If the <code>SpinnerModel</code> implementation doesn't support

     * the specified value then an <code>IllegalArgumentException</code>

     * is thrown.  For example a <code>SpinnerModel</code> for numbers might

     * only support values that are integer multiples of ten. In

     * that case, <code>model.setValue(new Number(11))</code>

     * would throw an exception.

     *

     * @throws IllegalArgumentException if <code>value</code> isn't allowed

     * @see #getValue

     */

    void setValue(Object value);

    /**

     * Return the object in the sequence that comes after the object returned

     * by <code>getValue()</code>. If the end of the sequence has been reached

     * then return null.  Calling this method does not effect <code>value</code>.

     *

     * @return the next legal value or null if one doesn't exist

     * @see #getValue

     * @see #getPreviousValue

     */

    Object getNextValue();

    /**

     * Return the object in the sequence that comes before the object returned

     * by <code>getValue()</code>.  If the end of the sequence has been reached then

     * return null. Calling this method does not effect <code>value</code>.

     *

     * @return the previous legal value or null if one doesn't exist

     * @see #getValue

     * @see #getNextValue

     */

    Object getPreviousValue();

    /**

     * Adds a <code>ChangeListener</code> to the model's listener list.  The

     * <code>ChangeListeners</code> must be notified when models <code>value</code>

     * changes.

     *

     * @param l the ChangeListener to add

     * @see #removeChangeListener

     */

    void addChangeListener(ChangeListener l);

    /**

     * Removes a <code>ChangeListener</code> from the model's listener list.

     *

     * @param l the ChangeListener to remove

     * @see #addChangeListener

     */

    void removeChangeListener(ChangeListener l);

}