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25 
26 /*
27  * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
28  *
29  * All rights reserved.
30  *
31  * Redistribution and use in source and binary forms, with or without
32  * modification, are permitted provided that the following conditions are met:
33  *
34  *  * Redistributions of source code must retain the above copyright notice,
35  *    this list of conditions and the following disclaimer.
36  *
37  *  * Redistributions in binary form must reproduce the above copyright notice,
38  *    this list of conditions and the following disclaimer in the documentation
39  *    and/or other materials provided with the distribution.
40  *
41  *  * Neither the name of JSR-310 nor the names of its contributors
42  *    may be used to endorse or promote products derived from this software
43  *    without specific prior written permission.
44  *
45  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
46  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
47  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
48  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
49  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
50  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
51  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
52  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
53  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
54  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
55  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
56  */
57 package java.time.temporal;
58 
59 import java.time.Duration;
60 
61 /**
62  * A standard set of date periods units.
63  * <p>
64  * This set of units provide unit-based access to manipulate a date, time or date-time.
65  * The standard set of units can be extended by implementing {@link TemporalUnit}.
66  * <p>
67  * These units are intended to be applicable in multiple calendar systems.
68  * For example, most non-ISO calendar systems define units of years, months and days,
69  * just with slightly different rules.
70  * The documentation of each unit explains how it operates.
71  *
72  * @implSpec
73  * This is a final, immutable and thread-safe enum.
74  *
75  * @since 1.8
76  */
77 public enum ChronoUnit implements TemporalUnit {
78 
79     /**
80      * Unit that represents the concept of a nanosecond, the smallest supported unit of time.
81      * For the ISO calendar system, it is equal to the 1,000,000,000th part of the second unit.
82      */
83     NANOS("Nanos", Duration.ofNanos(1)),
84     /**
85      * Unit that represents the concept of a microsecond.
86      * For the ISO calendar system, it is equal to the 1,000,000th part of the second unit.
87      */
88     MICROS("Micros", Duration.ofNanos(1000)),
89     /**
90      * Unit that represents the concept of a millisecond.
91      * For the ISO calendar system, it is equal to the 1000th part of the second unit.
92      */
93     MILLIS("Millis", Duration.ofNanos(1000_000)),
94     /**
95      * Unit that represents the concept of a second.
96      * For the ISO calendar system, it is equal to the second in the SI system
97      * of units, except around a leap-second.
98      */
99     SECONDS("Seconds", Duration.ofSeconds(1)),
100     /**
101      * Unit that represents the concept of a minute.
102      * For the ISO calendar system, it is equal to 60 seconds.
103      */
104     MINUTES("Minutes", Duration.ofSeconds(60)),
105     /**
106      * Unit that represents the concept of an hour.
107      * For the ISO calendar system, it is equal to 60 minutes.
108      */
109     HOURS("Hours", Duration.ofSeconds(3600)),
110     /**
111      * Unit that represents the concept of half a day, as used in AM/PM.
112      * For the ISO calendar system, it is equal to 12 hours.
113      */
114     HALF_DAYS("HalfDays", Duration.ofSeconds(43200)),
115     /**
116      * Unit that represents the concept of a day.
117      * For the ISO calendar system, it is the standard day from midnight to midnight.
118      * The estimated duration of a day is {@code 24 Hours}.
119      * <p>
120      * When used with other calendar systems it must correspond to the day defined by
121      * the rising and setting of the Sun on Earth. It is not required that days begin
122      * at midnight - when converting between calendar systems, the date should be
123      * equivalent at midday.
124      */
125     DAYS("Days", Duration.ofSeconds(86400)),
126     /**
127      * Unit that represents the concept of a week.
128      * For the ISO calendar system, it is equal to 7 days.
129      * <p>
130      * When used with other calendar systems it must correspond to an integral number of days.
131      */
132     WEEKS("Weeks", Duration.ofSeconds(7 * 86400L)),
133     /**
134      * Unit that represents the concept of a month.
135      * For the ISO calendar system, the length of the month varies by month-of-year.
136      * The estimated duration of a month is one twelfth of {@code 365.2425 Days}.
137      * <p>
138      * When used with other calendar systems it must correspond to an integral number of days.
139      */
140     MONTHS("Months", Duration.ofSeconds(31556952L / 12)),
141     /**
142      * Unit that represents the concept of a year.
143      * For the ISO calendar system, it is equal to 12 months.
144      * The estimated duration of a year is {@code 365.2425 Days}.
145      * <p>
146      * When used with other calendar systems it must correspond to an integral number of days
147      * or months roughly equal to a year defined by the passage of the Earth around the Sun.
148      */
149     YEARS("Years", Duration.ofSeconds(31556952L)),
150     /**
151      * Unit that represents the concept of a decade.
152      * For the ISO calendar system, it is equal to 10 years.
153      * <p>
154      * When used with other calendar systems it must correspond to an integral number of days
155      * and is normally an integral number of years.
156      */
157     DECADES("Decades", Duration.ofSeconds(31556952L * 10L)),
158     /**
159      * Unit that represents the concept of a century.
160      * For the ISO calendar system, it is equal to 100 years.
161      * <p>
162      * When used with other calendar systems it must correspond to an integral number of days
163      * and is normally an integral number of years.
164      */
165     CENTURIES("Centuries", Duration.ofSeconds(31556952L * 100L)),
166     /**
167      * Unit that represents the concept of a millennium.
168      * For the ISO calendar system, it is equal to 1000 years.
169      * <p>
170      * When used with other calendar systems it must correspond to an integral number of days
171      * and is normally an integral number of years.
172      */
173     MILLENNIA("Millennia", Duration.ofSeconds(31556952L * 1000L)),
174     /**
175      * Unit that represents the concept of an era.
176      * The ISO calendar system doesn't have eras thus it is impossible to add
177      * an era to a date or date-time.
178      * The estimated duration of the era is artificially defined as {@code 1,000,000,000 Years}.
179      * <p>
180      * When used with other calendar systems there are no restrictions on the unit.
181      */
182     ERAS("Eras", Duration.ofSeconds(31556952L * 1000_000_000L)),
183     /**
184      * Artificial unit that represents the concept of forever.
185      * This is primarily used with {@link TemporalField} to represent unbounded fields
186      * such as the year or era.
187      * The estimated duration of the era is artificially defined as the largest duration
188      * supported by {@code Duration}.
189      */
190     FOREVER("Forever", Duration.ofSeconds(Long.MAX_VALUE, 999_999_999));
191 
192     private final String name;
193     private final Duration duration;
194 
ChronoUnit(String name, Duration estimatedDuration)195     private ChronoUnit(String name, Duration estimatedDuration) {
196         this.name = name;
197         this.duration = estimatedDuration;
198     }
199 
200     //-----------------------------------------------------------------------
201     /**
202      * Gets the estimated duration of this unit in the ISO calendar system.
203      * <p>
204      * All of the units in this class have an estimated duration.
205      * Days vary due to daylight saving time, while months have different lengths.
206      *
207      * @return the estimated duration of this unit, not null
208      */
209     @Override
getDuration()210     public Duration getDuration() {
211         return duration;
212     }
213 
214     /**
215      * Checks if the duration of the unit is an estimate.
216      * <p>
217      * All time units in this class are considered to be accurate, while all date
218      * units in this class are considered to be estimated.
219      * <p>
220      * This definition ignores leap seconds, but considers that Days vary due to
221      * daylight saving time and months have different lengths.
222      *
223      * @return true if the duration is estimated, false if accurate
224      */
225     @Override
isDurationEstimated()226     public boolean isDurationEstimated() {
227         return this.compareTo(DAYS) >= 0;
228     }
229 
230     //-----------------------------------------------------------------------
231     /**
232      * Checks if this unit is a date unit.
233      * <p>
234      * All units from days to eras inclusive are date-based.
235      * Time-based units and {@code FOREVER} return false.
236      *
237      * @return true if a date unit, false if a time unit
238      */
239     @Override
isDateBased()240     public boolean isDateBased() {
241         return this.compareTo(DAYS) >= 0 && this != FOREVER;
242     }
243 
244     /**
245      * Checks if this unit is a time unit.
246      * <p>
247      * All units from nanos to half-days inclusive are time-based.
248      * Date-based units and {@code FOREVER} return false.
249      *
250      * @return true if a time unit, false if a date unit
251      */
252     @Override
isTimeBased()253     public boolean isTimeBased() {
254         return this.compareTo(DAYS) < 0;
255     }
256 
257     //-----------------------------------------------------------------------
258     @Override
isSupportedBy(Temporal temporal)259     public boolean isSupportedBy(Temporal temporal) {
260         return temporal.isSupported(this);
261     }
262 
263     @SuppressWarnings("unchecked")
264     @Override
addTo(R temporal, long amount)265     public <R extends Temporal> R addTo(R temporal, long amount) {
266         return (R) temporal.plus(amount, this);
267     }
268 
269     //-----------------------------------------------------------------------
270     @Override
between(Temporal temporal1Inclusive, Temporal temporal2Exclusive)271     public long between(Temporal temporal1Inclusive, Temporal temporal2Exclusive) {
272         return temporal1Inclusive.until(temporal2Exclusive, this);
273     }
274 
275     //-----------------------------------------------------------------------
276     @Override
toString()277     public String toString() {
278         return name;
279     }
280 
281 }
282