    001/* ===========================================================
    002 * JFreeChart : a free chart library for the Java(tm) platform
    003 * ===========================================================
    004 *
    005 * (C) Copyright 2000-2011, 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 * [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 * DefaultKeyedValue.java
    029 * ----------------------
    030 * (C) Copyright 2002-2008, by Object Refinery Limited.
    031 *
    032 * Original Author:  David Gilbert (for Object Refinery Limited);
    033 * Contributor(s):   -;
    034 *
    035 * Changes:
    036 * --------
    037 * 31-Oct-2002 : Version 1 (DG);
    038 * 13-Mar-2003 : Added equals() method, and implemented Serializable (DG);
    039 * 18-Aug-2003 : Implemented Cloneable (DG);
    040 * 18-Aug-2004 : Moved from org.jfree.data --> org.jfree.data.base (DG);
    041 * 15-Sep-2004 : Added PublicCloneable interface (DG);
    042 * ------------- JFREECHART 1.0.x ---------------------------------------------
    043 * 11-Jun-2007 : Added toString() method to help with debugging (DG);
    044 * 15-Feb-2008 : Prevent null key (DG);
    045 * 07-Apr-2008 : Removed to-do item (DG);
    046 *
    047 */
    048
    049package org.jfree.data;
    050
    051import java.io.Serializable;
    052
    053import org.jfree.util.PublicCloneable;
    054
    055/**
    056 * A (key, value) pair.  This class provides a default implementation
    057 * of the {@link KeyedValue} interface.
    058 */
    059public class DefaultKeyedValue implements KeyedValue, Cloneable,
    060        PublicCloneable, Serializable {
    061
    062    /** For serialization. */
    063    private static final long serialVersionUID = -7388924517460437712L;
    064
    065    /** The key. */
    066    private Comparable key;
    067
    068    /** The value. */
    069    private Number value;
    070
    071    /**
    072     * Creates a new (key, value) item.
    073     *
    074     * @param key  the key (should be immutable, <code>null</code> not
    075     *         permitted).
    076     * @param value  the value (<code>null</code> permitted).
    077     */
    078    public DefaultKeyedValue(Comparable key, Number value) {
    079        if (key == null) {
    080            throw new IllegalArgumentException("Null 'key' argument.");
    081        }
    082        this.key = key;
    083        this.value = value;
    084    }
    085
    086    /**
    087     * Returns the key.
    088     *
    089     * @return The key (never <code>null</code>).
    090     */
    091    public Comparable getKey() {
    092        return this.key;
    093    }
    094
    095    /**
    096     * Returns the value.
    097     *
    098     * @return The value (possibly <code>null</code>).
    099     */
    100    public Number getValue() {
    101        return this.value;
    102    }
    103
    104    /**
    105     * Sets the value.
    106     *
    107     * @param value  the value (<code>null</code> permitted).
    108     */
    109    public synchronized void setValue(Number value) {
    110        this.value = value;
    111    }
    112
    113    /**
    114     * Tests this key-value pair for equality with an arbitrary object.
    115     *
    116     * @param obj  the object (<code>null</code> permitted).
    117     *
    118     * @return A boolean.
    119     */
    120    public boolean equals(Object obj) {
    121        if (obj == this) {
    122            return true;
    123        }
    124        if (!(obj instanceof DefaultKeyedValue)) {
    125            return false;
    126        }
    127        DefaultKeyedValue that = (DefaultKeyedValue) obj;
    128
    129        if (!this.key.equals(that.key)) {
    130            return false;
    131        }
    132        if (this.value != null
    133                ? !this.value.equals(that.value) : that.value != null) {
    134            return false;
    135        }
    136        return true;
    137    }
    138
    139    /**
    140     * Returns a hash code.
    141     *
    142     * @return A hash code.
    143     */
    144    public int hashCode() {
    145        int result;
    146        result = (this.key != null ? this.key.hashCode() : 0);
    147        result = 29 * result + (this.value != null ? this.value.hashCode() : 0);
    148        return result;
    149    }
    150
    151    /**
    152     * Returns a clone.  It is assumed that both the key and value are
    153     * immutable objects, so only the references are cloned, not the objects
    154     * themselves.
    155     *
    156     * @return A clone.
    157     *
    158     * @throws CloneNotSupportedException Not thrown by this class, but
    159     *         subclasses (if any) might.
    160     */
    161    public Object clone() throws CloneNotSupportedException {
    162        DefaultKeyedValue clone = (DefaultKeyedValue) super.clone();
    163        return clone;
    164    }
    165
    166    /**
    167     * Returns a string representing this instance, primarily useful for
    168     * debugging.
    169     *
    170     * @return A string.
    171     */
    172    public String toString() {
    173        return "(" + this.key.toString() + ", " + this.value.toString() + ")";
    174    }
    175
    176}