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
043 package org.jfree.data;
044
045 import java.util.Comparator;
046
047 import 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 */
053 public 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 }