| 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; |
| 19 | import java.util.HashMap; |
| 20 | import org.joda.time.DurationField; |
| 21 | import org.joda.time.DurationFieldType; |
| 22 | |
| 23 | /** |
| 24 | * A placeholder implementation to use when a duration field is not supported. |
| 25 | * <p> |
| 26 | * UnsupportedDurationField is thread-safe and immutable. |
| 27 | * |
| 28 | * @author Brian S O'Neill |
| 29 | * @since 1.0 |
| 30 | */ |
| 31 | public final class UnsupportedDurationField extends DurationField implements Serializable { |
| 32 | |
| 33 | /** Serialization lock. */ |
| 34 | private static final long serialVersionUID = -6390301302770925357L; |
| 35 | |
| 36 | /** The cache of unsupported duration field instances */ |
| 37 | private static HashMap cCache; |
| 38 | |
| 39 | /** |
| 40 | * Gets an instance of UnsupportedDurationField for a specific named field. |
| 41 | * The returned instance is cached. |
| 42 | * |
| 43 | * @param type the type to obtain |
| 44 | * @return the instance |
| 45 | */ |
| 46 | public static synchronized UnsupportedDurationField getInstance(DurationFieldType type) { |
| 47 | UnsupportedDurationField field; |
| 48 | if (cCache == null) { |
| 49 | cCache = new HashMap(7); |
| 50 | field = null; |
| 51 | } else { |
| 52 | field = (UnsupportedDurationField) cCache.get(type); |
| 53 | } |
| 54 | if (field == null) { |
| 55 | field = new UnsupportedDurationField(type); |
| 56 | cCache.put(type, field); |
| 57 | } |
| 58 | return field; |
| 59 | } |
| 60 | |
| 61 | /** The name of the field */ |
| 62 | private final DurationFieldType iType; |
| 63 | |
| 64 | /** |
| 65 | * Constructor. |
| 66 | * |
| 67 | * @param type the type to use |
| 68 | */ |
| 69 | private UnsupportedDurationField(DurationFieldType type) { |
| 70 | iType = type; |
| 71 | } |
| 72 | |
| 73 | //----------------------------------------------------------------------- |
| 74 | // Design note: Simple Accessors return a suitable value, but methods |
| 75 | // intended to perform calculations throw an UnsupportedOperationException. |
| 76 | |
| 77 | public final DurationFieldType getType() { |
| 78 | return iType; |
| 79 | } |
| 80 | |
| 81 | public String getName() { |
| 82 | return iType.getName(); |
| 83 | } |
| 84 | |
| 85 | /** |
| 86 | * This field is not supported. |
| 87 | * |
| 88 | * @return false always |
| 89 | */ |
| 90 | public boolean isSupported() { |
| 91 | return false; |
| 92 | } |
| 93 | |
| 94 | /** |
| 95 | * This field is precise. |
| 96 | * |
| 97 | * @return true always |
| 98 | */ |
| 99 | public boolean isPrecise() { |
| 100 | return true; |
| 101 | } |
| 102 | |
| 103 | /** |
| 104 | * Always throws UnsupportedOperationException |
| 105 | * |
| 106 | * @throws UnsupportedOperationException |
| 107 | */ |
| 108 | public int getValue(long duration) { |
| 109 | throw unsupported(); |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Always throws UnsupportedOperationException |
| 114 | * |
| 115 | * @throws UnsupportedOperationException |
| 116 | */ |
| 117 | public long getValueAsLong(long duration) { |
| 118 | throw unsupported(); |
| 119 | } |
| 120 | |
| 121 | /** |
| 122 | * Always throws UnsupportedOperationException |
| 123 | * |
| 124 | * @throws UnsupportedOperationException |
| 125 | */ |
| 126 | public int getValue(long duration, long instant) { |
| 127 | throw unsupported(); |
| 128 | } |
| 129 | |
| 130 | /** |
| 131 | * Always throws UnsupportedOperationException |
| 132 | * |
| 133 | * @throws UnsupportedOperationException |
| 134 | */ |
| 135 | public long getValueAsLong(long duration, long instant) { |
| 136 | throw unsupported(); |
| 137 | } |
| 138 | |
| 139 | /** |
| 140 | * Always throws UnsupportedOperationException |
| 141 | * |
| 142 | * @throws UnsupportedOperationException |
| 143 | */ |
| 144 | public long getMillis(int value) { |
| 145 | throw unsupported(); |
| 146 | } |
| 147 | |
| 148 | /** |
| 149 | * Always throws UnsupportedOperationException |
| 150 | * |
| 151 | * @throws UnsupportedOperationException |
| 152 | */ |
| 153 | public long getMillis(long value) { |
| 154 | throw unsupported(); |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * Always throws UnsupportedOperationException |
| 159 | * |
| 160 | * @throws UnsupportedOperationException |
| 161 | */ |
| 162 | public long getMillis(int value, long instant) { |
| 163 | throw unsupported(); |
| 164 | } |
| 165 | |
| 166 | /** |
| 167 | * Always throws UnsupportedOperationException |
| 168 | * |
| 169 | * @throws UnsupportedOperationException |
| 170 | */ |
| 171 | public long getMillis(long value, long instant) { |
| 172 | throw unsupported(); |
| 173 | } |
| 174 | |
| 175 | /** |
| 176 | * Always throws UnsupportedOperationException |
| 177 | * |
| 178 | * @throws UnsupportedOperationException |
| 179 | */ |
| 180 | public long add(long instant, int value) { |
| 181 | throw unsupported(); |
| 182 | } |
| 183 | |
| 184 | /** |
| 185 | * Always throws UnsupportedOperationException |
| 186 | * |
| 187 | * @throws UnsupportedOperationException |
| 188 | */ |
| 189 | public long add(long instant, long value) { |
| 190 | throw unsupported(); |
| 191 | } |
| 192 | |
| 193 | /** |
| 194 | * Always throws UnsupportedOperationException |
| 195 | * |
| 196 | * @throws UnsupportedOperationException |
| 197 | */ |
| 198 | public int getDifference(long minuendInstant, long subtrahendInstant) { |
| 199 | throw unsupported(); |
| 200 | } |
| 201 | |
| 202 | /** |
| 203 | * Always throws UnsupportedOperationException |
| 204 | * |
| 205 | * @throws UnsupportedOperationException |
| 206 | */ |
| 207 | public long getDifferenceAsLong(long minuendInstant, long subtrahendInstant) { |
| 208 | throw unsupported(); |
| 209 | } |
| 210 | |
| 211 | /** |
| 212 | * Always returns zero. |
| 213 | * |
| 214 | * @return zero always |
| 215 | */ |
| 216 | public long getUnitMillis() { |
| 217 | return 0; |
| 218 | } |
| 219 | |
| 220 | /** |
| 221 | * Always returns zero, indicating that sort order is not relevent. |
| 222 | * |
| 223 | * @return zero always |
| 224 | */ |
| 225 | public int compareTo(Object durationField) { |
| 226 | return 0; |
| 227 | } |
| 228 | |
| 229 | //------------------------------------------------------------------------ |
| 230 | /** |
| 231 | * Compares this duration field to another. |
| 232 | * |
| 233 | * @param obj the object to compare to |
| 234 | * @return true if equal |
| 235 | */ |
| 236 | public boolean equals(Object obj) { |
| 237 | if (this == obj) { |
| 238 | return true; |
| 239 | } else if (obj instanceof UnsupportedDurationField) { |
| 240 | UnsupportedDurationField other = (UnsupportedDurationField) obj; |
| 241 | if (other.getName() == null) { |
| 242 | return (getName() == null); |
| 243 | } |
| 244 | return (other.getName().equals(getName())); |
| 245 | } |
| 246 | return false; |
| 247 | } |
| 248 | |
| 249 | /** |
| 250 | * Gets a suitable hashcode. |
| 251 | * |
| 252 | * @return the hashcode |
| 253 | */ |
| 254 | public int hashCode() { |
| 255 | return getName().hashCode(); |
| 256 | } |
| 257 | |
| 258 | /** |
| 259 | * Get a suitable debug string. |
| 260 | * |
| 261 | * @return debug string |
| 262 | */ |
| 263 | public String toString() { |
| 264 | return "UnsupportedDurationField[" + getName() + ']'; |
| 265 | } |
| 266 | |
| 267 | /** |
| 268 | * Ensure proper singleton serialization |
| 269 | */ |
| 270 | private Object readResolve() { |
| 271 | return getInstance(iType); |
| 272 | } |
| 273 | |
| 274 | private UnsupportedOperationException unsupported() { |
| 275 | return new UnsupportedOperationException(iType + " field is unsupported"); |
| 276 | } |
| 277 | |
| 278 | } |