001 /*
002 * Copyright 2001-2009 Stephen Colebourne
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016 package org.joda.time.field;
017
018 import java.io.Serializable;
019 import java.util.HashMap;
020
021 import org.joda.time.DurationField;
022 import org.joda.time.DurationFieldType;
023
024 /**
025 * A placeholder implementation to use when a duration field is not supported.
026 * <p>
027 * UnsupportedDurationField is thread-safe and immutable.
028 *
029 * @author Brian S O'Neill
030 * @since 1.0
031 */
032 public final class UnsupportedDurationField extends DurationField implements Serializable {
033
034 /** Serialization lock. */
035 private static final long serialVersionUID = -6390301302770925357L;
036
037 /** The cache of unsupported duration field instances */
038 private static HashMap<DurationFieldType, UnsupportedDurationField> cCache;
039
040 /**
041 * Gets an instance of UnsupportedDurationField for a specific named field.
042 * The returned instance is cached.
043 *
044 * @param type the type to obtain
045 * @return the instance
046 */
047 public static synchronized UnsupportedDurationField getInstance(DurationFieldType type) {
048 UnsupportedDurationField field;
049 if (cCache == null) {
050 cCache = new HashMap<DurationFieldType, UnsupportedDurationField>(7);
051 field = null;
052 } else {
053 field = cCache.get(type);
054 }
055 if (field == null) {
056 field = new UnsupportedDurationField(type);
057 cCache.put(type, field);
058 }
059 return field;
060 }
061
062 /** The name of the field */
063 private final DurationFieldType iType;
064
065 /**
066 * Constructor.
067 *
068 * @param type the type to use
069 */
070 private UnsupportedDurationField(DurationFieldType type) {
071 iType = type;
072 }
073
074 //-----------------------------------------------------------------------
075 // Design note: Simple Accessors return a suitable value, but methods
076 // intended to perform calculations throw an UnsupportedOperationException.
077
078 public final DurationFieldType getType() {
079 return iType;
080 }
081
082 public String getName() {
083 return iType.getName();
084 }
085
086 /**
087 * This field is not supported.
088 *
089 * @return false always
090 */
091 public boolean isSupported() {
092 return false;
093 }
094
095 /**
096 * This field is precise.
097 *
098 * @return true always
099 */
100 public boolean isPrecise() {
101 return true;
102 }
103
104 /**
105 * Always throws UnsupportedOperationException
106 *
107 * @throws UnsupportedOperationException
108 */
109 public int getValue(long duration) {
110 throw unsupported();
111 }
112
113 /**
114 * Always throws UnsupportedOperationException
115 *
116 * @throws UnsupportedOperationException
117 */
118 public long getValueAsLong(long duration) {
119 throw unsupported();
120 }
121
122 /**
123 * Always throws UnsupportedOperationException
124 *
125 * @throws UnsupportedOperationException
126 */
127 public int getValue(long duration, long instant) {
128 throw unsupported();
129 }
130
131 /**
132 * Always throws UnsupportedOperationException
133 *
134 * @throws UnsupportedOperationException
135 */
136 public long getValueAsLong(long duration, long instant) {
137 throw unsupported();
138 }
139
140 /**
141 * Always throws UnsupportedOperationException
142 *
143 * @throws UnsupportedOperationException
144 */
145 public long getMillis(int value) {
146 throw unsupported();
147 }
148
149 /**
150 * Always throws UnsupportedOperationException
151 *
152 * @throws UnsupportedOperationException
153 */
154 public long getMillis(long value) {
155 throw unsupported();
156 }
157
158 /**
159 * Always throws UnsupportedOperationException
160 *
161 * @throws UnsupportedOperationException
162 */
163 public long getMillis(int value, long instant) {
164 throw unsupported();
165 }
166
167 /**
168 * Always throws UnsupportedOperationException
169 *
170 * @throws UnsupportedOperationException
171 */
172 public long getMillis(long value, long instant) {
173 throw unsupported();
174 }
175
176 /**
177 * Always throws UnsupportedOperationException
178 *
179 * @throws UnsupportedOperationException
180 */
181 public long add(long instant, int value) {
182 throw unsupported();
183 }
184
185 /**
186 * Always throws UnsupportedOperationException
187 *
188 * @throws UnsupportedOperationException
189 */
190 public long add(long instant, long value) {
191 throw unsupported();
192 }
193
194 /**
195 * Always throws UnsupportedOperationException
196 *
197 * @throws UnsupportedOperationException
198 */
199 public int getDifference(long minuendInstant, long subtrahendInstant) {
200 throw unsupported();
201 }
202
203 /**
204 * Always throws UnsupportedOperationException
205 *
206 * @throws UnsupportedOperationException
207 */
208 public long getDifferenceAsLong(long minuendInstant, long subtrahendInstant) {
209 throw unsupported();
210 }
211
212 /**
213 * Always returns zero.
214 *
215 * @return zero always
216 */
217 public long getUnitMillis() {
218 return 0;
219 }
220
221 /**
222 * Always returns zero, indicating that sort order is not relevent.
223 *
224 * @return zero always
225 */
226 public int compareTo(DurationField durationField) {
227 return 0;
228 }
229
230 //------------------------------------------------------------------------
231 /**
232 * Compares this duration field to another.
233 *
234 * @param obj the object to compare to
235 * @return true if equal
236 */
237 public boolean equals(Object obj) {
238 if (this == obj) {
239 return true;
240 } else if (obj instanceof UnsupportedDurationField) {
241 UnsupportedDurationField other = (UnsupportedDurationField) obj;
242 if (other.getName() == null) {
243 return (getName() == null);
244 }
245 return (other.getName().equals(getName()));
246 }
247 return false;
248 }
249
250 /**
251 * Gets a suitable hashcode.
252 *
253 * @return the hashcode
254 */
255 public int hashCode() {
256 return getName().hashCode();
257 }
258
259 /**
260 * Get a suitable debug string.
261 *
262 * @return debug string
263 */
264 public String toString() {
265 return "UnsupportedDurationField[" + getName() + ']';
266 }
267
268 /**
269 * Ensure proper singleton serialization
270 */
271 private Object readResolve() {
272 return getInstance(iType);
273 }
274
275 private UnsupportedOperationException unsupported() {
276 return new UnsupportedOperationException(iType + " field is unsupported");
277 }
278
279 }