/* SpinnerModel.java --
   Copyright (C) 2003, 2004  Free Software Foundation, Inc.

This file is part of GNU Classpath.

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it under the terms of the GNU General Public License as published by
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package javax.swing;

import javax.swing.event.ChangeListener;

/**
 * The data model that is used in {@link JSpinner}s.
 *
 * @since 1.4
 */
public interface SpinnerModel
{
  /**
   * Sets the current value of the model to that specified.
   * Implementations can choose to refuse to accept the value
   * and throw an exception instead.  For example, a date model
   * may throw invalid dates, or a list model may throw out
   * values which don't exist in the underlying list.  Models
   * may also throw out unusual values, such as null.  The decision
   * is left to the discretion of the implementator.  If the
   * operation succeeds, the implementation should also notify
   * any registered <code>ChangeListener</code>s.
   *
   * @param value The new value of the model.
   * @throws IllegalArgumentException if the model does not accept
   *         the given value.
   */
  void setValue(Object value);

  /**
   * Returns the current value of the model.
   *
   * @return The current value.
   */
  Object getValue();

  /**
   * Returns the next value from the model.  If the model is bounded,
   * this method may return null when the upper bound is met.
   * The current value is not changed.
   *
   * @return The next value, or null if there are no more values
   *         to retrieve.
   */
  Object getNextValue();

  /**
   * Returns the previous value from the model.  If the model is
   * bounded, this method may return null when the lower bound is
   * met.  The current value is not changed.
   *
   * @return The previous value, or null if there are no more
   *         values to retrieve.
   */
  Object getPreviousValue();

  /**
   * Adds a <code>ChangeListener</code> to the list of registered
   * listeners.  Each listener is notified when the current value
   * is changed.
   *
   * @param listener The new listener to register.
   */
  void addChangeListener(ChangeListener listener);

  /**
   * Removes a given <code>ChangeListener</code> from the list
   * of registered listeners.
   *
   * @param listener The listener to remove.
   */
  void removeChangeListener(ChangeListener listener);

}