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