MutableDouble


1   /*
2    * Copyright 2004-2005 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.apache.commons.lang.mutable;
18  
19  import org.apache.commons.lang.math.NumberUtils;
20  
21  /**
22   * A mutable <code>double</code> wrapper.
23   * 
24   * @see Double
25   * @since 2.1
26   * @version $Id: MutableDouble.java 161243 2005-04-14 04:30:28Z ggregory $
27   */
28  public class MutableDouble extends Number   implements Comparable  , Mutable {
29  
30      /** Serialization lock. */
31      private static final long serialVersionUID = 1587163916L;
32  
33      /** The mutable value. */
34      private double value;
35  
36      /**
37       * Constructs a new MutableDouble with the default value of zero.
38       */
39      public MutableDouble() {
40          super();
41      }
42  
43      /**
44       * Constructs a new MutableDouble with the specified value.
45       * 
46       * @param value
47       *            a value.
48       */
49      public MutableDouble(double value) {
50          super();
51          this.value = value;
52      }
53  
54      /**
55       * Constructs a new MutableDouble with the specified value.
56       * 
57       * @param value
58       *            a value.
59       * @throws NullPointerException
60       *             if the object is null
61       */
62      public MutableDouble(Number   value) {
63          super();
64          this.value = value.doubleValue();
65      }
66  
67      //-----------------------------------------------------------------------
68      /**
69       * Gets the value as a Double instance.
70       * 
71       * @return the value as a Double
72       */
73      public Object   getValue() {
74          return new Double  (this.value);
75      }
76  
77      /**
78       * Sets the value.
79       * 
80       * @param value
81       *            the value to set
82       */
83      public void setValue(double value) {
84          this.value = value;
85      }
86  
87      /**
88       * Sets the value from any Number instance.
89       * 
90       * @param value
91       *            the value to set
92       * @throws NullPointerException
93       *             if the object is null
94       * @throws ClassCastException
95       *             if the type is not a {@link Number}
96       */
97      public void setValue(Object   value) {
98          setValue(((Number  ) value).doubleValue());
99      }
100 
101     //-----------------------------------------------------------------------
102     // shortValue and bytValue rely on Number implementation
103     /**
104      * Returns the value of this MutableDouble as a int.
105      *
106      * @return the numeric value represented by this object after conversion to type int.
107      */
108     public int intValue() {
109         return (int) value;
110     }
111 
112     /**
113      * Returns the value of this MutableDouble as a long.
114      *
115      * @return the numeric value represented by this object after conversion to type long.
116      */
117     public long longValue() {
118         return (long) value;
119     }
120 
121     /**
122      * Returns the value of this MutableDouble as a float.
123      *
124      * @return the numeric value represented by this object after conversion to type float.
125      */
126     public float floatValue() {
127         return (float) value;
128     }
129 
130     /**
131      * Returns the value of this MutableDouble as a double.
132      *
133      * @return the numeric value represented by this object after conversion to type double.
134      */
135     public double doubleValue() {
136         return value;
137     }
138 
139     /**
140      * Checks whether the double value is the special NaN value.
141      * 
142      * @return true if NaN
143      */
144     public boolean isNaN() {
145         return Double.isNaN(value);
146     }
147 
148     /**
149      * Checks whether the double value is infinite.
150      * 
151      * @return true if infinite
152      */
153     public boolean isInfinite() {
154         return Double.isInfinite(value);
155     }
156 
157     //-----------------------------------------------------------------------
158     /**
159      * Compares this object against the specified object. The result is <code>true</code> if and only if the argument
160      * is not <code>null</code> and is a <code>Double</code> object that represents a double that has the identical
161      * bit pattern to the bit pattern of the double represented by this object. For this purpose, two
162      * <code>double</code> values are considered to be the same if and only if the method
163      * {@link Double#doubleToLongBits(double)}returns the same long value when applied to each.
164      * <p>
165      * Note that in most cases, for two instances of class <code>Double</code>,<code>d1</code> and <code>d2</code>,
166      * the value of <code>d1.equals(d2)</code> is <code>true</code> if and only if <blockquote>
167      * 
168      * <pre>
169      *   d1.doubleValue()&nbsp;== d2.doubleValue()
170      * </pre>
171      * 
172      * </blockquote>
173      * <p>
174      * also has the value <code>true</code>. However, there are two exceptions:
175      * <ul>
176      * <li>If <code>d1</code> and <code>d2</code> both represent <code>Double.NaN</code>, then the
177      * <code>equals</code> method returns <code>true</code>, even though <code>Double.NaN==Double.NaN</code> has
178      * the value <code>false</code>.
179      * <li>If <code>d1</code> represents <code>+0.0</code> while <code>d2</code> represents <code>-0.0</code>,
180      * or vice versa, the <code>equal</code> test has the value <code>false</code>, even though
181      * <code>+0.0==-0.0</code> has the value <code>true</code>. This allows hashtables to operate properly.
182      * </ul>
183      * 
184      * @param obj
185      *            the object to compare with.
186      * @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
187      */
188     public boolean equals(Object   obj) {
189         return (obj instanceof MutableDouble)
190             && (Double.doubleToLongBits(((MutableDouble) obj).value) == Double.doubleToLongBits(value));
191     }
192 
193     /**
194      * Returns a suitable hashcode for this mutable.
195      * 
196      * @return a suitable hashcode
197      */
198     public int hashCode() {
199         long bits = Double.doubleToLongBits(value);
200         return (int) (bits ^ (bits >>> 32));
201     }
202 
203     /**
204      * Compares this mutable to another in ascending order.
205      * 
206      * @param obj
207      *            the mutable to compare to
208      * @return negative if this is less, zero if equal, positive if greater
209      * @throws ClassCastException if the argument is not a MutableDouble
210      */
211     public int compareTo(Object   obj) {
212         MutableDouble other = (MutableDouble) obj;
213         double anotherVal = other.value;
214         return NumberUtils.compare(value, anotherVal);
215     }
216 
217     /**
218      * Returns the String value of this mutable.
219      * 
220      * @return the mutable value as a string
221      */
222     public String   toString() {
223         return String.valueOf(value);
224     }
225 
226 }
227
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