KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > joda > time > field > BaseDurationField


1 /*
2  * Copyright 2001-2005 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 JavaDoc;
19 import org.joda.time.DurationField;
20 import org.joda.time.DurationFieldType;
21
22 /**
23  * BaseDurationField provides the common behaviour for DurationField
24  * implementations.
25  * <p>
26  * This class should generally not be used directly by API users. The
27  * DurationField class should be used when different kinds of DurationField
28  * objects are to be referenced.
29  * <p>
30  * BaseDurationField is thread-safe and immutable, and its subclasses must
31  * be as well.
32  *
33  * @author Brian S O'Neill
34  * @see DecoratedDurationField
35  * @since 1.0
36  */
37 public abstract class BaseDurationField extends DurationField implements Serializable JavaDoc {
38
39     /** Serialization lock. */
40     private static final long serialVersionUID = -2554245107589433218L;
41
42     /** A desriptive name for the field. */
43     private final DurationFieldType iType;
44
45     protected BaseDurationField(DurationFieldType type) {
46         super();
47         if (type == null) {
48             throw new IllegalArgumentException JavaDoc("The type must not be null");
49         }
50         iType = type;
51     }
52
53     public final DurationFieldType getType() {
54         return iType;
55     }
56
57     public final String JavaDoc getName() {
58         return iType.getName();
59     }
60
61     /**
62      * @return true always
63      */
64     public final boolean isSupported() {
65         return true;
66     }
67
68     //------------------------------------------------------------------------
69 /**
70      * Get the value of this field from the milliseconds, which is approximate
71      * if this field is imprecise.
72      *
73      * @param duration the milliseconds to query, which may be negative
74      * @return the value of the field, in the units of the field, which may be
75      * negative
76      */
77     public int getValue(long duration) {
78         return FieldUtils.safeToInt(getValueAsLong(duration));
79     }
80
81     /**
82      * Get the value of this field from the milliseconds, which is approximate
83      * if this field is imprecise.
84      *
85      * @param duration the milliseconds to query, which may be negative
86      * @return the value of the field, in the units of the field, which may be
87      * negative
88      */
89     public long getValueAsLong(long duration) {
90         return duration / getUnitMillis();
91     }
92
93     /**
94      * Get the value of this field from the milliseconds relative to an
95      * instant.
96      *
97      * <p>If the milliseconds is positive, then the instant is treated as a
98      * "start instant". If negative, the instant is treated as an "end
99      * instant".
100      *
101      * <p>The default implementation returns
102      * <code>Utils.safeToInt(getAsLong(millisDuration, instant))</code>.
103      *
104      * @param duration the milliseconds to query, which may be negative
105      * @param instant the start instant to calculate relative to
106      * @return the value of the field, in the units of the field, which may be
107      * negative
108      */
109     public int getValue(long duration, long instant) {
110         return FieldUtils.safeToInt(getValueAsLong(duration, instant));
111     }
112
113     /**
114      * Get the millisecond duration of this field from its value, which is
115      * approximate if this field is imprecise.
116      *
117      * @param value the value of the field, which may be negative
118      * @return the milliseconds that the field represents, which may be
119      * negative
120      */
121     public long getMillis(int value) {
122         return value * getUnitMillis(); // safe
123 }
124
125     /**
126      * Get the millisecond duration of this field from its value, which is
127      * approximate if this field is imprecise.
128      *
129      * @param value the value of the field, which may be negative
130      * @return the milliseconds that the field represents, which may be
131      * negative
132      */
133     public long getMillis(long value) {
134         return FieldUtils.safeMultiply(value, getUnitMillis());
135     }
136
137     // Calculation API
138 //------------------------------------------------------------------------
139 public int getDifference(long minuendInstant, long subtrahendInstant) {
140         return FieldUtils.safeToInt(getDifferenceAsLong(minuendInstant, subtrahendInstant));
141     }
142
143     //------------------------------------------------------------------------
144 public int compareTo(Object JavaDoc durationField) {
145         DurationField otherField = (DurationField) durationField;
146         long otherMillis = otherField.getUnitMillis();
147         long thisMillis = getUnitMillis();
148         // cannot do (thisMillis - otherMillis) as can overflow
149 if (thisMillis == otherMillis) {
150             return 0;
151         }
152         if (thisMillis < otherMillis) {
153             return -1;
154         } else {
155             return 1;
156         }
157     }
158
159     /**
160      * Get a suitable debug string.
161      *
162      * @return debug string
163      */
164     public String JavaDoc toString() {
165         return "DurationField[" + getName() + ']';
166     }
167
168 }
169
Popular Tags