/* ===========================================================

 * JFreeChart : a free chart library for the Java(tm) platform

 * ===========================================================

 *

 * (C) Copyright 2000-2004, by Object Refinery Limited and Contributors.

 *

 * Project Info:  http://www.jfree.org/jfreechart/index.html

 *

 * This library is free software; you can redistribute it and/or modify it under the terms

 * of the GNU Lesser General Public License as published by the Free Software Foundation;

 * either version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License along with this

 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,

 * Boston, MA 02111-1307, USA.

 *

 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 

 * in the United States and other countries.]

 *

 * -----------------------------

 * DefaultKeyedValueDataset.java

 * -----------------------------

 * (C) Copyright 2003, 2004, by Object Refinery Limited.

 *

 * Original Author:  David Gilbert (for Object Refinery Limited);

 * Contributor(s):   -;

 *

 * $Id $

 *

 * Changes

 * -------

 * 27-Mar-2003 : Version 1 (DG);

 * 18-Aug-2003 : Implemented Cloneable (DG);

 *

 */



package org.jfree.data.general;



import java.io.Serializable;



import org.jfree.data.DefaultKeyedValue;

import org.jfree.data.KeyedValue;

import org.jfree.util.ObjectUtils;



/**

 * A default implementation of the {@link KeyedValueDataset} interface.

 *

 */

public class DefaultKeyedValueDataset extends AbstractDataset

                                      implements KeyedValueDataset, Serializable {



    /** Storage for the data. */

    private KeyedValue data;



    /**

     * Constructs a new dataset, initially empty.

     */

    public DefaultKeyedValueDataset() {

        this(null);

    }



    /**

     * Creates a new dataset with the specified initial value.

     *

     * @param key  the key.

     * @param value  the value (<code>null</code> permitted).

     */

    public DefaultKeyedValueDataset(final Comparable key, final Number value) {

        this(new DefaultKeyedValue(key, value));

    }



    /**

     * Creates a new dataset that uses the data from a {@link KeyedValue} instance.

     *

     * @param data  the data (<code>null</code> permitted).

     */

    public DefaultKeyedValueDataset(final KeyedValue data) {

        this.data = data;

    }



    /**

     * Returns the key associated with the value, or <code>null</code> if the dataset has no 

     * data item.

     *

     * @return the key.

     */

    public Comparable getKey() {

        Comparable result = null;

        if (this.data != null) {

            result = this.data.getKey();

        }

        return result;

    }



    /**

     * Returns the value.

     *

     * @return the value (possibly <code>null</code>).

     */

    public Number getValue() {

        Number result = null;

        if (this.data != null) {

            result = this.data.getValue();

        }

        return result;

    }



    /**

     * Updates the value.

     *

     * @param value  the new value (<code>null</code> permitted).

     */

    public void updateValue(final Number value) {

        if (this.data == null) {

            throw new RuntimeException("updateValue: can't update null.");

        }

        setValue(this.data.getKey(), value);

    }



    /**

     * Sets the value for the dataset and sends a {@link DatasetChangeEvent} to all registered 

     * listeners.

     *

     * @param key  the key.

     * @param value  the value (<code>null</code> permitted).

     */

    public void setValue(final Comparable key, final Number value) {

        this.data = new DefaultKeyedValue(key, value);

        notifyListeners(new DatasetChangeEvent(this, this));

    }



    /**

     * Tests this dataset for equality with an arbitrary object.

     *

     * @param obj  the object.

     *

     * @return A boolean.

     */

    public boolean equals(final Object obj) {



        if (obj == null) {

            return false;

        }



        if (obj == this) {

            return true;

        }



        if (!(obj instanceof KeyedValueDataset)) {

            return false;

        }



        final KeyedValueDataset kvd = (KeyedValueDataset) obj;

        if (this.data == null) {

            if (kvd.getKey() != null || kvd.getValue() != null) {

                return false;

            }

            return true;

        }

        

        if (!ObjectUtils.equal(this.data.getKey(), kvd.getKey())) {

            return false;

        }

        if (!ObjectUtils.equal(this.data.getValue(), kvd.getValue())) {

            return false;

        }

        return true;

    }



    /**

     * Returns a hash code.

     * 

     * @return a hash code.

     */

    public int hashCode() {

        return (this.data != null ? this.data.hashCode() : 0);

    }



    /**

     * Creates a clone of the dataset.

     * 

     * @return A clone.

     * 

     * @throws CloneNotSupportedException This class will not throw this exception, but subclasses 

     *         (if any) might.

     */

    public Object clone() throws CloneNotSupportedException {

        final DefaultKeyedValueDataset clone = (DefaultKeyedValueDataset) super.clone();

        return clone;    

    }

    

}

