001: /* ===========================================================
002: * JFreeChart : a free chart library for the Java(tm) platform
003: * ===========================================================
004: *
005: * (C) Copyright 2000-2005, 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 2003-2005, by Object Refinery Limited.
031: *
032: * Original Author: David Gilbert (for Object Refinery Limited);
033: * Contributor(s): -;
034: *
035: * $Id: KeyedValueComparator.java,v 1.4.2.1 2005/10/25 21:29:13 mungady Exp $
036: *
037: * Changes:
038: * --------
039: * 05-Mar-2003 : Version 1 (DG);
040: * 27-Aug-2003 : Moved SortOrder from org.jfree.data --> org.jfree.util (DG);
041: * 12-Jan-2005 : Added accessor methods (DG);
042: *
043: */
044:
045: package org.jfree.data;
046:
047: import java.util.Comparator;
048:
049: import org.jfree.util.SortOrder;
050:
051: /**
052: * A utility class that can compare and order two {@link KeyedValue} instances
053: * and sort them into ascending or descending order by key or by value.
054: */
055: public class KeyedValueComparator implements Comparator {
056:
057: /** The comparator type. */
058: private KeyedValueComparatorType type;
059:
060: /** The sort order. */
061: private SortOrder order;
062:
063: /**
064: * Creates a new comparator.
065: *
066: * @param type the type (<code>BY_KEY</code> or <code>BY_VALUE</code>,
067: * <code>null</code> not permitted).
068: * @param order the order (<code>null</code> not permitted).
069: */
070: public KeyedValueComparator(KeyedValueComparatorType type,
071: SortOrder order) {
072: if (order == null) {
073: throw new IllegalArgumentException("Null 'order' argument.");
074: }
075: this .type = type;
076: this .order = order;
077: }
078:
079: /**
080: * Returns the type.
081: *
082: * @return The type (never <code>null</code>).
083: */
084: public KeyedValueComparatorType getType() {
085: return this .type;
086: }
087:
088: /**
089: * Returns the sort order.
090: *
091: * @return The sort order (never <code>null</code>).
092: */
093: public SortOrder getOrder() {
094: return this .order;
095: }
096:
097: /**
098: * Compares two {@link KeyedValue} instances and returns an
099: * <code>int</code> that indicates the relative order of the two objects.
100: *
101: * @param o1 object 1.
102: * @param o2 object 2.
103: *
104: * @return An int indicating the relative order of the objects.
105: */
106: public int compare(Object o1, Object o2) {
107:
108: if (o2 == null) {
109: return -1;
110: }
111: if (o1 == null) {
112: return 1;
113: }
114:
115: int result;
116:
117: KeyedValue kv1 = (KeyedValue) o1;
118: KeyedValue kv2 = (KeyedValue) o2;
119:
120: if (this .type == KeyedValueComparatorType.BY_KEY) {
121: if (this .order.equals(SortOrder.ASCENDING)) {
122: result = kv1.getKey().compareTo(kv2.getKey());
123: } else if (this .order.equals(SortOrder.DESCENDING)) {
124: result = kv2.getKey().compareTo(kv1.getKey());
125: } else {
126: throw new IllegalArgumentException(
127: "Unrecognised sort order.");
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: } else if (d1 < d2) {
144: result = -1;
145: } else {
146: result = 0;
147: }
148: } else if (this .order.equals(SortOrder.DESCENDING)) {
149: if (d1 > d2) {
150: result = -1;
151: } else if (d1 < d2) {
152: result = 1;
153: } else {
154: result = 0;
155: }
156: } else {
157: throw new IllegalArgumentException(
158: "Unrecognised sort order.");
159: }
160: } else {
161: throw new IllegalArgumentException("Unrecognised type.");
162: }
163:
164: return result;
165: }
166:
167: }
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