001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2008, 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 * KeyedValueComparator.java
029 * -------------------------
030 * (C) Copyright 2003-2008, by Object Refinery Limited.
031 *
032 * Original Author:  David Gilbert (for Object Refinery Limited);
033 * Contributor(s):   -;
034 *
035 * Changes:
036 * --------
037 * 05-Mar-2003 : Version 1 (DG);
038 * 27-Aug-2003 : Moved SortOrder from org.jfree.data --> org.jfree.util (DG);
039 * 12-Jan-2005 : Added accessor methods (DG);
040 *
041 */
042
043package org.jfree.data;
044
045import java.util.Comparator;
046
047import org.jfree.util.SortOrder;
048
049/**
050 * A utility class that can compare and order two {@link KeyedValue} instances
051 * and sort them into ascending or descending order by key or by value.
052 */
053public class KeyedValueComparator implements Comparator {
054
055    /** The comparator type. */
056    private KeyedValueComparatorType type;
057
058    /** The sort order. */
059    private SortOrder order;
060
061    /**
062     * Creates a new comparator.
063     *
064     * @param type  the type (<code>BY_KEY</code> or <code>BY_VALUE</code>,
065     *              <code>null</code> not permitted).
066     * @param order  the order (<code>null</code> not permitted).
067     */
068    public KeyedValueComparator(KeyedValueComparatorType type,
069                                SortOrder order) {
070        if (order == null) {
071            throw new IllegalArgumentException("Null 'order' argument.");
072        }
073        this.type = type;
074        this.order = order;
075    }
076
077    /**
078     * Returns the type.
079     *
080     * @return The type (never <code>null</code>).
081     */
082    public KeyedValueComparatorType getType() {
083        return this.type;
084    }
085
086    /**
087     * Returns the sort order.
088     *
089     * @return The sort order (never <code>null</code>).
090     */
091    public SortOrder getOrder() {
092        return this.order;
093    }
094
095    /**
096     * Compares two {@link KeyedValue} instances and returns an
097     * <code>int</code> that indicates the relative order of the two objects.
098     *
099     * @param o1  object 1.
100     * @param o2  object 2.
101     *
102     * @return An int indicating the relative order of the objects.
103     */
104    public int compare(Object o1, Object o2) {
105
106        if (o2 == null) {
107            return -1;
108        }
109        if (o1 == null) {
110            return 1;
111        }
112
113        int result;
114
115        KeyedValue kv1 = (KeyedValue) o1;
116        KeyedValue kv2 = (KeyedValue) o2;
117
118        if (this.type == KeyedValueComparatorType.BY_KEY) {
119            if (this.order.equals(SortOrder.ASCENDING)) {
120                result = kv1.getKey().compareTo(kv2.getKey());
121            }
122            else if (this.order.equals(SortOrder.DESCENDING)) {
123                result = kv2.getKey().compareTo(kv1.getKey());
124            }
125            else {
126                throw new IllegalArgumentException("Unrecognised sort order.");
127            }
128        }
129        else if (this.type == KeyedValueComparatorType.BY_VALUE) {
130            Number n1 = kv1.getValue();
131            Number n2 = kv2.getValue();
132            if (n2 == null) {
133                return -1;
134            }
135            if (n1 == null) {
136                return 1;
137            }
138            double d1 = n1.doubleValue();
139            double d2 = n2.doubleValue();
140            if (this.order.equals(SortOrder.ASCENDING)) {
141                if (d1 > d2) {
142                    result = 1;
143                }
144                else if (d1 < d2) {
145                    result = -1;
146                }
147                else {
148                    result = 0;
149                }
150            }
151            else if (this.order.equals(SortOrder.DESCENDING)) {
152                if (d1 > d2) {
153                    result = -1;
154                }
155                else if (d1 < d2) {
156                    result = 1;
157                }
158                else {
159                    result = 0;
160                }
161            }
162            else {
163                throw new IllegalArgumentException("Unrecognised sort order.");
164            }
165        }
166        else {
167            throw new IllegalArgumentException("Unrecognised type.");
168        }
169
170        return result;
171    }
172
173}