001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-present, by David Gilbert 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 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
025 * Other names may be trademarks of their respective owners.]
026 *
027 * ----------------
028 * KeyedValues.java
029 * ----------------
030 * (C) Copyright 2002-present, by David Gilbert.
031 *
032 * Original Author:  David Gilbert;
033 * Contributor(s):   Tracy Hiltbrand (generics for bug fix to PiePlot);
034 *
035 */
036
037package org.jfree.data;
038
039import java.util.List;
040
041/**
042 * An ordered list of (key, value) items where the keys are unique and
043 * non-{@code null}.
044 *
045 * @param <K> the key type ({@code String} is a good default).
046 * 
047 * @see Values
048 * @see DefaultKeyedValues
049 */
050public interface KeyedValues<K extends Comparable<K>> extends Values {
051
052    /**
053     * Returns the key associated with the item at a given position.  Note
054     * that some implementations allow re-ordering of the data items, so the
055     * result may be transient.
056     *
057     * @param index  the item index (in the range {@code 0} to
058     *     {@code getItemCount() - 1}).
059     *
060     * @return The key (never {@code null}).
061     *
062     * @throws IndexOutOfBoundsException if {@code index} is not in the
063     *     specified range.
064     */
065    K getKey(int index);
066
067    /**
068     * Returns the index for a given key.
069     *
070     * @param key  the key ({@code null} not permitted).
071     *
072     * @return The index, or {@code -1} if the key is unrecognised.
073     *
074     * @throws IllegalArgumentException if {@code key} is {@code null}.
075     */
076    int getIndex(K key);
077
078    /**
079     * Returns the keys for the values in the collection.  Note that you can
080     * access the values in this collection by key or by index.  For this
081     * reason, the key order is important - this method should return the keys
082     * in order.  The returned list may be unmodifiable.
083     *
084     * @return The keys (never {@code null}).
085     */
086    List<K> getKeys();
087
088    /**
089     * Returns the value for a given key.
090     *
091     * @param key  the key.
092     *
093     * @return The value (possibly {@code null}).
094     *
095     * @throws UnknownKeyException if the key is not recognised.
096     */
097    Number getValue(K key);
098
099}