1/* 2 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26/* 27 * This file is available under and governed by the GNU General Public 28 * License version 2 only, as published by the Free Software Foundation. 29 * However, the following notice accompanied the original version of this 30 * file: 31 * 32 * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos 33 * 34 * All rights reserved. 35 * 36 * Redistribution and use in source and binary forms, with or without 37 * modification, are permitted provided that the following conditions are met: 38 * 39 * * Redistributions of source code must retain the above copyright notice, 40 * this list of conditions and the following disclaimer. 41 * 42 * * Redistributions in binary form must reproduce the above copyright notice, 43 * this list of conditions and the following disclaimer in the documentation 44 * and/or other materials provided with the distribution. 45 * 46 * * Neither the name of JSR-310 nor the names of its contributors 47 * may be used to endorse or promote products derived from this software 48 * without specific prior written permission. 49 * 50 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 51 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 52 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 53 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 54 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 55 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 56 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 57 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 58 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 59 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 60 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 61 */ 62package java.time.temporal; 63 64import java.time.DateTimeException; 65import java.time.Duration; 66import java.time.LocalTime; 67import java.time.Period; 68import java.time.chrono.ChronoLocalDate; 69import java.time.chrono.ChronoLocalDateTime; 70import java.time.chrono.ChronoZonedDateTime; 71 72/** 73 * A unit of date-time, such as Days or Hours. 74 * <p> 75 * Measurement of time is built on units, such as years, months, days, hours, minutes and seconds. 76 * Implementations of this interface represent those units. 77 * <p> 78 * An instance of this interface represents the unit itself, rather than an amount of the unit. 79 * See {@link Period} for a class that represents an amount in terms of the common units. 80 * <p> 81 * The most commonly used units are defined in {@link ChronoUnit}. 82 * Further units are supplied in {@link IsoFields}. 83 * Units can also be written by application code by implementing this interface. 84 * <p> 85 * The unit works using double dispatch. Client code calls methods on a date-time like 86 * {@code LocalDateTime} which check if the unit is a {@code ChronoUnit}. 87 * If it is, then the date-time must handle it. 88 * Otherwise, the method call is re-dispatched to the matching method in this interface. 89 * 90 * @implSpec 91 * This interface must be implemented with care to ensure other classes operate correctly. 92 * All implementations that can be instantiated must be final, immutable and thread-safe. 93 * It is recommended to use an enum where possible. 94 * 95 * @since 1.8 96 */ 97public interface TemporalUnit { 98 99 /** 100 * Gets the duration of this unit, which may be an estimate. 101 * <p> 102 * All units return a duration measured in standard nanoseconds from this method. 103 * The duration will be positive and non-zero. 104 * For example, an hour has a duration of {@code 60 * 60 * 1,000,000,000ns}. 105 * <p> 106 * Some units may return an accurate duration while others return an estimate. 107 * For example, days have an estimated duration due to the possibility of 108 * daylight saving time changes. 109 * To determine if the duration is an estimate, use {@link #isDurationEstimated()}. 110 * 111 * @return the duration of this unit, which may be an estimate, not null 112 */ 113 Duration getDuration(); 114 115 /** 116 * Checks if the duration of the unit is an estimate. 117 * <p> 118 * All units have a duration, however the duration is not always accurate. 119 * For example, days have an estimated duration due to the possibility of 120 * daylight saving time changes. 121 * This method returns true if the duration is an estimate and false if it is 122 * accurate. Note that accurate/estimated ignores leap seconds. 123 * 124 * @return true if the duration is estimated, false if accurate 125 */ 126 boolean isDurationEstimated(); 127 128 //----------------------------------------------------------------------- 129 /** 130 * Checks if this unit represents a component of a date. 131 * <p> 132 * A date is time-based if it can be used to imply meaning from a date. 133 * It must have a {@linkplain #getDuration() duration} that is an integral 134 * multiple of the length of a standard day. 135 * Note that it is valid for both {@code isDateBased()} and {@code isTimeBased()} 136 * to return false, such as when representing a unit like 36 hours. 137 * 138 * @return true if this unit is a component of a date 139 */ 140 boolean isDateBased(); 141 142 /** 143 * Checks if this unit represents a component of a time. 144 * <p> 145 * A unit is time-based if it can be used to imply meaning from a time. 146 * It must have a {@linkplain #getDuration() duration} that divides into 147 * the length of a standard day without remainder. 148 * Note that it is valid for both {@code isDateBased()} and {@code isTimeBased()} 149 * to return false, such as when representing a unit like 36 hours. 150 * 151 * @return true if this unit is a component of a time 152 */ 153 boolean isTimeBased(); 154 155 //----------------------------------------------------------------------- 156 /** 157 * Checks if this unit is supported by the specified temporal object. 158 * <p> 159 * This checks that the implementing date-time can add/subtract this unit. 160 * This can be used to avoid throwing an exception. 161 * <p> 162 * This default implementation derives the value using 163 * {@link Temporal#plus(long, TemporalUnit)}. 164 * 165 * @param temporal the temporal object to check, not null 166 * @return true if the unit is supported 167 */ 168 default boolean isSupportedBy(Temporal temporal) { 169 if (temporal instanceof LocalTime) { 170 return isTimeBased(); 171 } 172 if (temporal instanceof ChronoLocalDate) { 173 return isDateBased(); 174 } 175 if (temporal instanceof ChronoLocalDateTime || temporal instanceof ChronoZonedDateTime) { 176 return true; 177 } 178 try { 179 temporal.plus(1, this); 180 return true; 181 } catch (UnsupportedTemporalTypeException ex) { 182 return false; 183 } catch (RuntimeException ex) { 184 try { 185 temporal.plus(-1, this); 186 return true; 187 } catch (RuntimeException ex2) { 188 return false; 189 } 190 } 191 } 192 193 /** 194 * Returns a copy of the specified temporal object with the specified period added. 195 * <p> 196 * The period added is a multiple of this unit. For example, this method 197 * could be used to add "3 days" to a date by calling this method on the 198 * instance representing "days", passing the date and the period "3". 199 * The period to be added may be negative, which is equivalent to subtraction. 200 * <p> 201 * There are two equivalent ways of using this method. 202 * The first is to invoke this method directly. 203 * The second is to use {@link Temporal#plus(long, TemporalUnit)}: 204 * <pre> 205 * // these two lines are equivalent, but the second approach is recommended 206 * temporal = thisUnit.addTo(temporal); 207 * temporal = temporal.plus(thisUnit); 208 * </pre> 209 * It is recommended to use the second approach, {@code plus(TemporalUnit)}, 210 * as it is a lot clearer to read in code. 211 * <p> 212 * Implementations should perform any queries or calculations using the units 213 * available in {@link ChronoUnit} or the fields available in {@link ChronoField}. 214 * If the unit is not supported an {@code UnsupportedTemporalTypeException} must be thrown. 215 * <p> 216 * Implementations must not alter the specified temporal object. 217 * Instead, an adjusted copy of the original must be returned. 218 * This provides equivalent, safe behavior for immutable and mutable implementations. 219 * 220 * @param <R> the type of the Temporal object 221 * @param temporal the temporal object to adjust, not null 222 * @param amount the amount of this unit to add, positive or negative 223 * @return the adjusted temporal object, not null 224 * @throws DateTimeException if the amount cannot be added 225 * @throws UnsupportedTemporalTypeException if the unit is not supported by the temporal 226 */ 227 <R extends Temporal> R addTo(R temporal, long amount); 228 229 //----------------------------------------------------------------------- 230 /** 231 * Calculates the amount of time between two temporal objects. 232 * <p> 233 * This calculates the amount in terms of this unit. The start and end 234 * points are supplied as temporal objects and must be of compatible types. 235 * The implementation will convert the second type to be an instance of the 236 * first type before the calculating the amount. 237 * The result will be negative if the end is before the start. 238 * For example, the amount in hours between two temporal objects can be 239 * calculated using {@code HOURS.between(startTime, endTime)}. 240 * <p> 241 * The calculation returns a whole number, representing the number of 242 * complete units between the two temporals. 243 * For example, the amount in hours between the times 11:30 and 13:29 244 * will only be one hour as it is one minute short of two hours. 245 * <p> 246 * There are two equivalent ways of using this method. 247 * The first is to invoke this method directly. 248 * The second is to use {@link Temporal#until(Temporal, TemporalUnit)}: 249 * <pre> 250 * // these two lines are equivalent 251 * between = thisUnit.between(start, end); 252 * between = start.until(end, thisUnit); 253 * </pre> 254 * The choice should be made based on which makes the code more readable. 255 * <p> 256 * For example, this method allows the number of days between two dates to 257 * be calculated: 258 * <pre> 259 * long daysBetween = DAYS.between(start, end); 260 * // or alternatively 261 * long daysBetween = start.until(end, DAYS); 262 * </pre> 263 * <p> 264 * Implementations should perform any queries or calculations using the units 265 * available in {@link ChronoUnit} or the fields available in {@link ChronoField}. 266 * If the unit is not supported an {@code UnsupportedTemporalTypeException} must be thrown. 267 * Implementations must not alter the specified temporal objects. 268 * 269 * @implSpec 270 * Implementations must begin by checking to if the two temporals have the 271 * same type using {@code getClass()}. If they do not, then the result must be 272 * obtained by calling {@code temporal1Inclusive.until(temporal2Exclusive, this)}. 273 * 274 * @param temporal1Inclusive the base temporal object, not null 275 * @param temporal2Exclusive the other temporal object, exclusive, not null 276 * @return the amount of time between temporal1Inclusive and temporal2Exclusive 277 * in terms of this unit; positive if temporal2Exclusive is later than 278 * temporal1Inclusive, negative if earlier 279 * @throws DateTimeException if the amount cannot be calculated, or the end 280 * temporal cannot be converted to the same type as the start temporal 281 * @throws UnsupportedTemporalTypeException if the unit is not supported by the temporal 282 * @throws ArithmeticException if numeric overflow occurs 283 */ 284 long between(Temporal temporal1Inclusive, Temporal temporal2Exclusive); 285 286 //----------------------------------------------------------------------- 287 /** 288 * Gets a descriptive name for the unit. 289 * <p> 290 * This should be in the plural and upper-first camel case, such as 'Days' or 'Minutes'. 291 * 292 * @return the name of this unit, not null 293 */ 294 @Override 295 String toString(); 296 297} 298