001    /* ===========================================================
002     * JFreeChart : a free chart library for the Java(tm) platform
003     * ===========================================================
004     *
005     * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
006     *
007     * Project Info:  http://www.jfree.org/jfreechart/index.html
008     *
009     * This library is free software; you can redistribute it and/or modify it 
010     * under the terms of the GNU Lesser General Public License as published by 
011     * the Free Software Foundation; either version 2.1 of the License, or 
012     * (at your option) any later version.
013     *
014     * This library is distributed in the hope that it will be useful, but 
015     * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
016     * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
017     * License for more details.
018     *
019     * You should have received a copy of the GNU Lesser General Public
020     * License along with this library; if not, write to the Free Software
021     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
022     * USA.  
023     *
024     * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
025     * in the United States and other countries.]
026     *
027     * ----------------
028     * KeyedValues.java
029     * ----------------
030     * (C) Copyright 2002-2005, by Object Refinery Limited.
031     *
032     * Original Author:  David Gilbert (for Object Refinery Limited);
033     * Contributor(s):   -;
034     *
035     * $Id: KeyedValues.java,v 1.3.2.1 2005/10/25 21:29:13 mungady Exp $
036     *
037     * Changes:
038     * --------
039     * 23-Oct-2002 : Version 1 (DG);
040     * 12-Jan-2005 : Updated Javadocs to specify new behaviour when key
041     *               is not recognised (DG);
042     *
043     */
044    
045    package org.jfree.data;
046    
047    import java.util.List;
048    
049    /**
050     * An ordered list of (key, value) items.
051     *
052     * @see Values
053     * @see DefaultKeyedValues
054     */
055    public interface KeyedValues extends Values {
056    
057        /**
058         * Returns the key associated with an item (value).
059         *
060         * @param index  the item index (zero-based).
061         *
062         * @return The key.
063         * 
064         * @throws IndexOutOfBoundsException if <code>index</code> is out of bounds.
065         */
066        public Comparable getKey(int index);
067    
068        /**
069         * Returns the index for a given key.
070         *
071         * @param key  the key.
072         *
073         * @return The index, or <code>-1</code> if the key is unrecognised.
074         */
075        public int getIndex(Comparable key);
076    
077        /**
078         * Returns the keys for the values in the collection.  Note that you can 
079         * access the values in this collection by key or by index.  For this 
080         * reason, the key order is important - this method should return the keys
081         * in order.  The returned list may be unmodifiable.
082         *
083         * @return The keys (never <code>null</code>).
084         */
085        public List getKeys();
086    
087        /**
088         * Returns the value for a given key.
089         *
090         * @param key  the key.
091         *
092         * @return The value (possibly <code>null</code>).
093         * 
094         * @throws UnknownKeyException if the key is not recognised.
095         */
096        public Number getValue(Comparable key);
097    
098    }