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1   /*
2    *  Copyright 2001-2009 Stephen Colebourne
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  package org.joda.time.field;
17  
18  import java.io.Serializable;
19  
20  import org.joda.time.DurationField;
21  import org.joda.time.DurationFieldType;
22  
23  /**
24   * Duration field class representing a field with a fixed unit length of one
25   * millisecond.
26   * <p>
27   * MillisDurationField is thread-safe and immutable.
28   *
29   * @author Brian S O'Neill
30   * @since 1.0
31   */
32  public final class MillisDurationField extends DurationField implements Serializable {
33  
34      /** Serialization lock. */
35      private static final long serialVersionUID = 2656707858124633367L;
36  
37      /** Singleton instance. */
38      public static final DurationField INSTANCE = new MillisDurationField();
39  
40      /**
41       * Restricted constructor.
42       */
43      private MillisDurationField() {
44          super();
45      }
46      
47      //------------------------------------------------------------------------
48      public DurationFieldType getType() {
49          return DurationFieldType.millis();
50      }
51  
52      public String getName() {
53          return "millis";
54      }
55  
56      /**
57       * Returns true as this field is supported.
58       * 
59       * @return true always
60       */
61      public boolean isSupported() {
62          return true;
63      }
64  
65      /**
66       * Returns true as this field is precise.
67       * 
68       * @return true always
69       */
70      public final boolean isPrecise() {
71          return true;
72      }
73  
74      /**
75       * Returns the amount of milliseconds per unit value of this field.
76       *
77       * @return one always
78       */
79      public final long getUnitMillis() {
80          return 1;
81      }
82  
83      //------------------------------------------------------------------------
84      public int getValue(long duration) {
85          return FieldUtils.safeToInt(duration);
86      }
87  
88      public long getValueAsLong(long duration) {
89          return duration;
90      }
91  
92      public int getValue(long duration, long instant) {
93          return FieldUtils.safeToInt(duration);
94      }
95  
96      public long getValueAsLong(long duration, long instant) {
97          return duration;
98      }
99  
100     public long getMillis(int value) {
101         return value;
102     }
103 
104     public long getMillis(long value) {
105         return value;
106     }
107 
108     public long getMillis(int value, long instant) {
109         return value;
110     }
111 
112     public long getMillis(long value, long instant) {
113         return value;
114     }
115 
116     public long add(long instant, int value) {
117         return FieldUtils.safeAdd(instant, value);
118     }
119 
120     public long add(long instant, long value) {
121         return FieldUtils.safeAdd(instant, value);
122     }
123 
124     public int getDifference(long minuendInstant, long subtrahendInstant) {
125         return FieldUtils.safeToInt(FieldUtils.safeSubtract(minuendInstant, subtrahendInstant));
126     }
127 
128     public long getDifferenceAsLong(long minuendInstant, long subtrahendInstant) {
129         return FieldUtils.safeSubtract(minuendInstant, subtrahendInstant);
130     }
131 
132     //------------------------------------------------------------------------
133     public int compareTo(DurationField otherField) {
134         long otherMillis = otherField.getUnitMillis();
135         long thisMillis = getUnitMillis();
136         // cannot do (thisMillis - otherMillis) as can overflow
137         if (thisMillis == otherMillis) {
138             return 0;
139         }
140         if (thisMillis < otherMillis) {
141             return -1;
142         } else {
143             return 1;
144         }
145     }
146 
147     public boolean equals(Object obj) {
148         if (obj instanceof MillisDurationField) {
149             return getUnitMillis() == ((MillisDurationField) obj).getUnitMillis();
150         }
151         return false;
152     }
153 
154     public int hashCode() {
155         return (int) getUnitMillis();
156     }
157 
158     /**
159      * Get a suitable debug string.
160      * 
161      * @return debug string
162      */
163     public String toString() {
164         return "DurationField[millis]";
165     }
166 
167     /**
168      * Deserialize to the singleton.
169      */
170     private Object readResolve() {
171         return INSTANCE;
172     }
173 
174 }