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 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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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 necessarily 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 preceding 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);
}