Source for org.jfree.data.KeyedValueComparator

   1: /* ===========================================================
   2:  * JFreeChart : a free chart library for the Java(tm) platform
   3:  * ===========================================================
   4:  *
   5:  * (C) Copyright 2000-2007, by Object Refinery Limited and Contributors.
   6:  *
   7:  * Project Info:  http://www.jfree.org/jfreechart/index.html
   8:  *
   9:  * This library is free software; you can redistribute it and/or modify it 
  10:  * under the terms of the GNU Lesser General Public License as published by 
  11:  * the Free Software Foundation; either version 2.1 of the License, or 
  12:  * (at your option) any later version.
  13:  *
  14:  * This library is distributed in the hope that it will be useful, but 
  15:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
  16:  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
  17:  * License for more details.
  18:  *
  19:  * You should have received a copy of the GNU Lesser General Public
  20:  * License along with this library; if not, write to the Free Software
  21:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
  22:  * USA.  
  23:  *
  24:  * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
  25:  * in the United States and other countries.]
  26:  *
  27:  * -------------------------
  28:  * KeyedValueComparator.java
  29:  * -------------------------
  30:  * (C) Copyright 2003-2007, by Object Refinery Limited.
  31:  *
  32:  * Original Author:  David Gilbert (for Object Refinery Limited);
  33:  * Contributor(s):   -;
  34:  *
  35:  * Changes:
  36:  * --------
  37:  * 05-Mar-2003 : Version 1 (DG);
  38:  * 27-Aug-2003 : Moved SortOrder from org.jfree.data --> org.jfree.util (DG);
  39:  * 12-Jan-2005 : Added accessor methods (DG);
  40:  *
  41:  */
  42: 
  43: package org.jfree.data;
  44: 
  45: import java.util.Comparator;
  46: 
  47: import org.jfree.util.SortOrder;
  48: 
  49: /**
  50:  * A utility class that can compare and order two {@link KeyedValue} instances 
  51:  * and sort them into ascending or descending order by key or by value.
  52:  */
  53: public class KeyedValueComparator implements Comparator {
  54: 
  55:     /** The comparator type. */
  56:     private KeyedValueComparatorType type;
  57: 
  58:     /** The sort order. */
  59:     private SortOrder order;
  60: 
  61:     /**
  62:      * Creates a new comparator.
  63:      *
  64:      * @param type  the type (<code>BY_KEY</code> or <code>BY_VALUE</code>, 
  65:      *              <code>null</code> not permitted).
  66:      * @param order  the order (<code>null</code> not permitted).
  67:      */
  68:     public KeyedValueComparator(KeyedValueComparatorType type, 
  69:                                 SortOrder order) {
  70:         if (order == null) {
  71:             throw new IllegalArgumentException("Null 'order' argument.");
  72:         }
  73:         this.type = type;
  74:         this.order = order;
  75:     }
  76: 
  77:     /**
  78:      * Returns the type.
  79:      * 
  80:      * @return The type (never <code>null</code>).
  81:      */
  82:     public KeyedValueComparatorType getType() {
  83:         return this.type;
  84:     }
  85:     
  86:     /**
  87:      * Returns the sort order.
  88:      * 
  89:      * @return The sort order (never <code>null</code>).
  90:      */
  91:     public SortOrder getOrder() {
  92:         return this.order;
  93:     }
  94:     
  95:     /**
  96:      * Compares two {@link KeyedValue} instances and returns an 
  97:      * <code>int</code> that indicates the relative order of the two objects.
  98:      *
  99:      * @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: }