001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2022, 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 2002-2022, 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 * @see Values
046 * @see DefaultKeyedValues
047 */
048public interface KeyedValues<K extends Comparable<K>> extends Values {
049
050    /**
051     * Returns the key associated with the item at a given position.  Note
052     * that some implementations allow re-ordering of the data items, so the
053     * result may be transient.
054     *
055     * @param index  the item index (in the range {@code 0} to
056     *     {@code getItemCount() - 1}).
057     *
058     * @return The key (never {@code null}).
059     *
060     * @throws IndexOutOfBoundsException if {@code index} is not in the
061     *     specified range.
062     */
063    K getKey(int index);
064
065    /**
066     * Returns the index for a given key.
067     *
068     * @param key  the key ({@code null} not permitted).
069     *
070     * @return The index, or {@code -1} if the key is unrecognised.
071     *
072     * @throws IllegalArgumentException if {@code key} is {@code null}.
073     */
074    int getIndex(K key);
075
076    /**
077     * Returns the keys for the values in the collection.  Note that you can
078     * access the values in this collection by key or by index.  For this
079     * reason, the key order is important - this method should return the keys
080     * in order.  The returned list may be unmodifiable.
081     *
082     * @return The keys (never {@code null}).
083     */
084    List<K> getKeys();
085
086    /**
087     * Returns the value for a given key.
088     *
089     * @param key  the key.
090     *
091     * @return The value (possibly {@code null}).
092     *
093     * @throws UnknownKeyException if the key is not recognised.
094     */
095    Number getValue(K key);
096
097}