| 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; |
| 17 | |
| 18 | /** |
| 19 | * Defines the calculation engine for duration fields. |
| 20 | * The interface defines a set of methods that manipulate a millisecond duration |
| 21 | * with regards to a single field, such as months or seconds. |
| 22 | * <p> |
| 23 | * This design is extensible so, if you wish, you can extract a different field from |
| 24 | * the millisecond duration. A number of standard implementations are provided to assist. |
| 25 | * |
| 26 | * @author Stephen Colebourne |
| 27 | * @author Brian S O'Neill |
| 28 | * @since 1.0 |
| 29 | */ |
| 30 | public abstract class DurationField implements Comparable { |
| 31 | |
| 32 | /** |
| 33 | * Get the type of the field. |
| 34 | * |
| 35 | * @return field type |
| 36 | */ |
| 37 | public abstract DurationFieldType getType(); |
| 38 | |
| 39 | /** |
| 40 | * Get the name of the field. |
| 41 | * <p> |
| 42 | * By convention, names are plural. |
| 43 | * |
| 44 | * @return field name |
| 45 | */ |
| 46 | public abstract String getName(); |
| 47 | |
| 48 | /** |
| 49 | * Returns true if this field is supported. |
| 50 | * |
| 51 | * @return true if this field is supported |
| 52 | */ |
| 53 | public abstract boolean isSupported(); |
| 54 | |
| 55 | /** |
| 56 | * Is this field precise. A precise field can calculate its value from |
| 57 | * milliseconds without needing a reference date. Put another way, a |
| 58 | * precise field's unit size is not variable. |
| 59 | * |
| 60 | * @return true if precise |
| 61 | * @see #getUnitMillis() |
| 62 | */ |
| 63 | public abstract boolean isPrecise(); |
| 64 | |
| 65 | /** |
| 66 | * Returns the amount of milliseconds per unit value of this field. For |
| 67 | * example, if this field represents "seconds", then this returns the |
| 68 | * milliseconds in one second. |
| 69 | * <p> |
| 70 | * For imprecise fields, the unit size is variable, and so this method |
| 71 | * returns a suitable average value. |
| 72 | * |
| 73 | * @return the unit size of this field, in milliseconds |
| 74 | * @see #isPrecise() |
| 75 | */ |
| 76 | public abstract long getUnitMillis(); |
| 77 | |
| 78 | //------------------------------------------------------------------------ |
| 79 | /** |
| 80 | * Get the value of this field from the milliseconds, which is approximate |
| 81 | * if this field is imprecise. |
| 82 | * |
| 83 | * @param duration the milliseconds to query, which may be negative |
| 84 | * @return the value of the field, in the units of the field, which may be |
| 85 | * negative |
| 86 | * @throws ArithmeticException if the value is too large for an int |
| 87 | */ |
| 88 | public abstract int getValue(long duration); |
| 89 | |
| 90 | /** |
| 91 | * Get the value of this field from the milliseconds, which is approximate |
| 92 | * if this field is imprecise. |
| 93 | * |
| 94 | * @param duration the milliseconds to query, which may be negative |
| 95 | * @return the value of the field, in the units of the field, which may be |
| 96 | * negative |
| 97 | */ |
| 98 | public abstract long getValueAsLong(long duration); |
| 99 | |
| 100 | /** |
| 101 | * Get the value of this field from the milliseconds relative to an |
| 102 | * instant. For precise fields this method produces the same result as for |
| 103 | * the single argument get method. |
| 104 | * <p> |
| 105 | * If the millisecond duration is positive, then the instant is treated as a |
| 106 | * "start instant". If negative, the instant is treated as an "end instant". |
| 107 | * |
| 108 | * @param duration the milliseconds to query, which may be negative |
| 109 | * @param instant the start instant to calculate relative to |
| 110 | * @return the value of the field, in the units of the field, which may be |
| 111 | * negative |
| 112 | * @throws ArithmeticException if the value is too large for an int |
| 113 | */ |
| 114 | public abstract int getValue(long duration, long instant); |
| 115 | |
| 116 | /** |
| 117 | * Get the value of this field from the milliseconds relative to an |
| 118 | * instant. For precise fields this method produces the same result as for |
| 119 | * the single argument get method. |
| 120 | * <p> |
| 121 | * If the millisecond duration is positive, then the instant is treated as a |
| 122 | * "start instant". If negative, the instant is treated as an "end instant". |
| 123 | * |
| 124 | * @param duration the milliseconds to query, which may be negative |
| 125 | * @param instant the start instant to calculate relative to |
| 126 | * @return the value of the field, in the units of the field, which may be |
| 127 | * negative |
| 128 | */ |
| 129 | public abstract long getValueAsLong(long duration, long instant); |
| 130 | |
| 131 | //------------------------------------------------------------------------ |
| 132 | /** |
| 133 | * Get the millisecond duration of this field from its value, which is |
| 134 | * approximate if this field is imprecise. |
| 135 | * |
| 136 | * @param value the value of the field, which may be negative |
| 137 | * @return the milliseconds that the field represents, which may be |
| 138 | * negative |
| 139 | */ |
| 140 | public abstract long getMillis(int value); |
| 141 | |
| 142 | /** |
| 143 | * Get the millisecond duration of this field from its value, which is |
| 144 | * approximate if this field is imprecise. |
| 145 | * |
| 146 | * @param value the value of the field, which may be negative |
| 147 | * @return the milliseconds that the field represents, which may be |
| 148 | * negative |
| 149 | */ |
| 150 | public abstract long getMillis(long value); |
| 151 | |
| 152 | /** |
| 153 | * Get the millisecond duration of this field from its value relative to an |
| 154 | * instant. For precise fields this method produces the same result as for |
| 155 | * the single argument getMillis method. |
| 156 | * <p> |
| 157 | * If the value is positive, then the instant is treated as a "start |
| 158 | * instant". If negative, the instant is treated as an "end instant". |
| 159 | * |
| 160 | * @param value the value of the field, which may be negative |
| 161 | * @param instant the instant to calculate relative to |
| 162 | * @return the millisecond duration that the field represents, which may be |
| 163 | * negative |
| 164 | */ |
| 165 | public abstract long getMillis(int value, long instant); |
| 166 | |
| 167 | /** |
| 168 | * Get the millisecond duration of this field from its value relative to an |
| 169 | * instant. For precise fields this method produces the same result as for |
| 170 | * the single argument getMillis method. |
| 171 | * <p> |
| 172 | * If the value is positive, then the instant is treated as a "start |
| 173 | * instant". If negative, the instant is treated as an "end instant". |
| 174 | * |
| 175 | * @param value the value of the field, which may be negative |
| 176 | * @param instant the instant to calculate relative to |
| 177 | * @return the millisecond duration that the field represents, which may be |
| 178 | * negative |
| 179 | */ |
| 180 | public abstract long getMillis(long value, long instant); |
| 181 | |
| 182 | /** |
| 183 | * Adds a duration value (which may be negative) to the instant. |
| 184 | * |
| 185 | * @param instant the milliseconds from 1970-01-01T00:00:00Z to add to |
| 186 | * @param value the value to add, in the units of the field |
| 187 | * @return the updated milliseconds |
| 188 | */ |
| 189 | public abstract long add(long instant, int value); |
| 190 | |
| 191 | /** |
| 192 | * Adds a duration value (which may be negative) to the instant. |
| 193 | * |
| 194 | * @param instant the milliseconds from 1970-01-01T00:00:00Z to add to |
| 195 | * @param value the value to add, in the units of the field |
| 196 | * @return the updated milliseconds |
| 197 | */ |
| 198 | public abstract long add(long instant, long value); |
| 199 | |
| 200 | /** |
| 201 | * Subtracts a duration value (which may be negative) from the instant. |
| 202 | * |
| 203 | * @param instant the milliseconds from 1970-01-01T00:00:00Z to subtract from |
| 204 | * @param value the value to subtract, in the units of the field |
| 205 | * @return the updated milliseconds |
| 206 | * @since 1.1 |
| 207 | */ |
| 208 | public long subtract(long instant, int value) { |
| 209 | if (value == Integer.MIN_VALUE) { |
| 210 | return subtract(instant, (long) value); |
| 211 | } |
| 212 | return add(instant, -value); |
| 213 | } |
| 214 | |
| 215 | /** |
| 216 | * Subtracts a duration value (which may be negative) from the instant. |
| 217 | * |
| 218 | * @param instant the milliseconds from 1970-01-01T00:00:00Z to subtract from |
| 219 | * @param value the value to subtract, in the units of the field |
| 220 | * @return the updated milliseconds |
| 221 | * @since 1.1 |
| 222 | */ |
| 223 | public long subtract(long instant, long value) { |
| 224 | if (value == Long.MIN_VALUE) { |
| 225 | throw new ArithmeticException("Long.MIN_VALUE cannot be negated"); |
| 226 | } |
| 227 | return add(instant, -value); |
| 228 | } |
| 229 | |
| 230 | /** |
| 231 | * Computes the difference between two instants, as measured in the units |
| 232 | * of this field. Any fractional units are dropped from the result. Calling |
| 233 | * getDifference reverses the effect of calling add. In the following code: |
| 234 | * |
| 235 | * <pre> |
| 236 | * long instant = ... |
| 237 | * int v = ... |
| 238 | * int age = getDifference(add(instant, v), instant); |
| 239 | * </pre> |
| 240 | * |
| 241 | * The value 'age' is the same as the value 'v'. |
| 242 | * |
| 243 | * @param minuendInstant the milliseconds from 1970-01-01T00:00:00Z to |
| 244 | * subtract from |
| 245 | * @param subtrahendInstant the milliseconds from 1970-01-01T00:00:00Z to |
| 246 | * subtract off the minuend |
| 247 | * @return the difference in the units of this field |
| 248 | */ |
| 249 | public abstract int getDifference(long minuendInstant, long subtrahendInstant); |
| 250 | |
| 251 | /** |
| 252 | * Computes the difference between two instants, as measured in the units |
| 253 | * of this field. Any fractional units are dropped from the result. Calling |
| 254 | * getDifference reverses the effect of calling add. In the following code: |
| 255 | * |
| 256 | * <pre> |
| 257 | * long instant = ... |
| 258 | * long v = ... |
| 259 | * long age = getDifferenceAsLong(add(instant, v), instant); |
| 260 | * </pre> |
| 261 | * |
| 262 | * The value 'age' is the same as the value 'v'. |
| 263 | * |
| 264 | * @param minuendInstant the milliseconds from 1970-01-01T00:00:00Z to |
| 265 | * subtract from |
| 266 | * @param subtrahendInstant the milliseconds from 1970-01-01T00:00:00Z to |
| 267 | * subtract off the minuend |
| 268 | * @return the difference in the units of this field |
| 269 | */ |
| 270 | public abstract long getDifferenceAsLong(long minuendInstant, long subtrahendInstant); |
| 271 | |
| 272 | /** |
| 273 | * Compares this duration field with another duration field for ascending |
| 274 | * unit millisecond order. This ordering is inconsistent with equals, as it |
| 275 | * ignores name and precision. |
| 276 | * |
| 277 | * @param durationField a duration field to check against |
| 278 | * @return negative value if this is less, 0 if equal, or positive value if greater |
| 279 | * @throws NullPointerException if the object is null |
| 280 | * @throws ClassCastException if the object type is not supported |
| 281 | */ |
| 282 | public abstract int compareTo(Object durationField); |
| 283 | |
| 284 | /** |
| 285 | * Returns a localized unit name of this field, using the given value as an |
| 286 | * aid. For example, the unit name may differ if it is plural. |
| 287 | * |
| 288 | * @param value the duration value to use for selecting a unit name |
| 289 | * @param locale the locale to use for selecting a name, null for default |
| 290 | */ |
| 291 | //String getUnitName(long value, Locale locale); |
| 292 | |
| 293 | /** |
| 294 | * Returns a localized unit name of this field, using the given value as an |
| 295 | * aid. For example, the unit name may differ if it is plural. |
| 296 | * |
| 297 | * @param value the duration value to use for selecting a unit name |
| 298 | */ |
| 299 | //String getUnitName(long value); |
| 300 | |
| 301 | /** |
| 302 | * Get the maximum length string returned by getUnitName. |
| 303 | * |
| 304 | * @param locale the locale to use for selecting a unit name, null for |
| 305 | * default |
| 306 | * @return the maximum name length |
| 307 | */ |
| 308 | //int getMaximumUnitNameLength(Locale locale); |
| 309 | |
| 310 | //------------------------------------------------------------------------ |
| 311 | /** |
| 312 | * Get a suitable debug string. |
| 313 | * |
| 314 | * @return debug string |
| 315 | */ |
| 316 | public abstract String toString(); |
| 317 | |
| 318 | } |