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) 2007-2012, 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 */
62 package java.time.temporal;
63
64 import java.io.IOException;
65 import java.io.InvalidObjectException;
66 import java.io.ObjectInput;
67 import java.io.ObjectOutput;
68 import java.io.ObjectStreamException;
69 import java.io.Serializable;
70 import java.time.DateTimeException;
71 import java.util.Objects;
72
73 /**
74 * A period of time, measured as an amount of a single unit, such as '3 Months'.
75 * <p>
76 * A {@code SimplePeriod} represents an amount of time measured in terms of a
77 * single {@link TemporalUnit unit}. Any unit may be used with this class.
78 * An alternative period implementation is {@link java.time.Period Period}, which
79 * allows a combination of date and time units.
80 * <p>
81 * This class is the return type from {@link TemporalUnit#between}.
82 * It can be used more generally, but is designed to enable the following code:
83 * <pre>
84 * date = date.minus(MONTHS.between(start, end));
85 * </pre>
86 * The unit determines which calendar systems it can be added to.
87 * <p>
88 * The period is modeled as a directed amount of time, meaning that the period may
89 * be negative. See {@link #abs()} to ensure the period is positive.
90 *
91 * <h3>Specification for implementors</h3>
92 * This class is immutable and thread-safe, providing that the unit is immutable,
93 * which it is required to be.
94 *
95 * @since 1.8
96 */
97 public final class SimplePeriod
98 implements TemporalAdder, TemporalSubtractor, Comparable<SimplePeriod>, Serializable {
99
100 /**
101 * Serialization version.
102 */
103 private static final long serialVersionUID = 3752975649629L;
104
105 /**
106 * The amount of the unit.
107 */
108 private final long amount;
109 /**
110 * The unit.
111 */
112 private final TemporalUnit unit;
113
114 //-----------------------------------------------------------------------
115 /**
116 * Obtains an instance of {@code SimplePeriod} from a period in the specified unit.
117 * <p>
118 * The parameters represent the two parts of a phrase like '6 Days'. For example:
119 * <pre>
120 * SimplePeriod.of(3, SECONDS);
121 * SimplePeriod.of(5, YEARS);
122 * </pre>
123 *
124 * @param amount the amount of the period, measured in terms of the unit, positive or negative
125 * @param unit the unit that the period is measured in, not null
126 * @return the period, not null
127 */
128 public static SimplePeriod of(long amount, TemporalUnit unit) {
129 Objects.requireNonNull(unit, "unit");
130 return new SimplePeriod(amount, unit);
131 }
132
133 //-----------------------------------------------------------------------
134 /**
135 * Constructor.
136 *
137 * @param amount the amount of the period, measured in terms of the unit, positive or negative
138 * @param unit the unit that the period is measured in, not null
139 */
140 SimplePeriod(long amount, TemporalUnit unit) {
141 this.amount = amount;
142 this.unit = unit;
143 }
144
145 //-----------------------------------------------------------------------
146 /**
147 * Gets the amount of this period.
148 * <p>
149 * In the phrase "2 Months", the amount is 2.
150 *
151 * @return the amount of the period, may be negative
152 */
153 public long getAmount() {
154 return amount;
155 }
156
157 /**
158 * Gets the unit of this period.
159 * <p>
160 * In the phrase "2 Months", the unit is "Months".
161 *
162 * @return the unit of the period, not null
163 */
164 public TemporalUnit getUnit() {
165 return unit;
166 }
167
168 //-------------------------------------------------------------------------
169 /**
170 * Adds this period to the specified temporal object.
171 * <p>
172 * This returns a temporal object of the same observable type as the input
173 * with this period added.
174 * <p>
175 * In most cases, it is clearer to reverse the calling pattern by using
176 * {@link Temporal#plus(TemporalAdder)}.
177 * <pre>
178 * // these two lines are equivalent, but the second approach is recommended
179 * dateTime = thisPeriod.addTo(dateTime);
180 * dateTime = dateTime.plus(thisPeriod);
181 * </pre>
182 * <p>
183 * The calculation is equivalent to invoking {@link Temporal#plus(long, TemporalUnit)}.
184 * <p>
185 * This instance is immutable and unaffected by this method call.
186 *
187 * @param temporal the temporal object to adjust, not null
188 * @return an object of the same type with the adjustment made, not null
189 * @throws DateTimeException if unable to add
190 * @throws ArithmeticException if numeric overflow occurs
191 */
192 @Override
193 public Temporal addTo(Temporal temporal) {
194 return temporal.plus(amount, unit);
195 }
196
197 /**
198 * Subtracts this period to the specified temporal object.
199 * <p>
200 * This returns a temporal object of the same observable type as the input
201 * with this period subtracted.
202 * <p>
203 * In most cases, it is clearer to reverse the calling pattern by using
204 * {@link Temporal#plus(TemporalAdder)}.
205 * <pre>
206 * // these two lines are equivalent, but the second approach is recommended
207 * dateTime = thisPeriod.subtractFrom(dateTime);
208 * dateTime = dateTime.minus(thisPeriod);
209 * </pre>
210 * <p>
211 * The calculation is equivalent to invoking {@link Temporal#minus(long, TemporalUnit)}.
212 * <p>
213 * This instance is immutable and unaffected by this method call.
214 *
215 * @param temporal the temporal object to adjust, not null
216 * @return an object of the same type with the adjustment made, not null
217 * @throws DateTimeException if unable to subtract
218 * @throws ArithmeticException if numeric overflow occurs
219 */
220 @Override
221 public Temporal subtractFrom(Temporal temporal) {
222 return temporal.minus(amount, unit);
223 }
224
225 //-----------------------------------------------------------------------
226 /**
227 * Returns a copy of this period with a positive amount.
228 * <p>
229 * This returns a period with the absolute value of the amount and the same unit.
230 * If the amount of this period is positive or zero, then this period is returned.
231 * If the amount of this period is negative, then a period with the negated
232 * amount is returned. If the amount equals {@code Long.MIN_VALUE},
233 * an {@code ArithmeticException} is thrown
234 * <p>
235 * This is useful to convert the result of {@link TemporalUnit#between} to
236 * a positive amount when you do not know which date is the earlier and
237 * which is the later.
238 *
239 * @return a period with a positive amount and the same unit, not null
240 * @throws ArithmeticException if the amount is {@code Long.MIN_VALUE}
241 */
242 public SimplePeriod abs() {
243 if (amount == Long.MIN_VALUE) {
244 throw new ArithmeticException("Unable to call abs() on MIN_VALUE");
245 }
246 return (amount >= 0 ? this : new SimplePeriod(-amount, unit));
247 }
248
249 //-----------------------------------------------------------------------
250 /**
251 * Compares this {@code SimplePeriod} to another period.
252 * <p>
253 * The comparison is based on the amount within the unit.
254 * Only two periods with the same unit can be compared.
255 *
256 * @param other the other period to compare to, not null
257 * @return the comparator value, negative if less, positive if greater
258 * @throws IllegalArgumentException if the units do not match
259 */
260 @Override
261 public int compareTo(SimplePeriod other) {
262 if (unit.equals(other.unit) == false) {
263 throw new IllegalArgumentException("Unable to compare periods with different units");
264 }
265 return Long.compare(amount, other.amount);
266 }
267
268 //-----------------------------------------------------------------------
269 /**
270 * Checks if this period is equal to another period.
271 * <p>
272 * The comparison is based on the amount and unit.
273 *
274 * @param obj the object to check, null returns false
275 * @return true if this is equal to the other period
276 */
277 @Override
278 public boolean equals(Object obj) {
279 if (this == obj) {
280 return true;
281 }
282 if (obj instanceof SimplePeriod) {
283 SimplePeriod other = (SimplePeriod) obj;
284 return amount == other.amount && unit.equals(other.unit);
285 }
286 return false;
287 }
288
289 /**
290 * A hash code for this period.
291 *
292 * @return a suitable hash code
293 */
294 @Override
295 public int hashCode() {
296 return unit.hashCode() ^ (int) (amount ^ (amount >>> 32));
297 }
298
299 //-----------------------------------------------------------------------
300 /**
301 * Outputs this period as a {@code String}, such as {@code 2 Months}.
302 * <p>
303 * The string consists of the amount, then a space, then the unit name.
304 *
305 * @return a string representation of this period, not null
306 */
307 @Override
308 public String toString() {
309 return amount + " " + unit.getName();
310 }
311
312 //-----------------------------------------------------------------------
313 /**
314 * Writes the object using a
315 * <a href="../../../serialized-form.html#java.time.temporal.Ser">dedicated serialized form</a>.
316 * <pre>
317 * out.writeByte(10); // identifies this as a SimplePeriod
318 * out.writeLong(amount);
319 * out.writeObject(unit);
320 * </pre>
321 *
322 * @return the instance of {@code Ser}, not null
323 */
324 private Object writeReplace() {
325 return new Ser(Ser.SIMPLE_PERIOD_TYPE, this);
326 }
327
328 /**
329 * Defend against malicious streams.
330 * @return never
331 * @throws InvalidObjectException always
332 */
333 private Object readResolve() throws ObjectStreamException {
334 throw new InvalidObjectException("Deserialization via serialization delegate");
335 }
336
337 void writeExternal(ObjectOutput out) throws IOException {
338 out.writeLong(amount);
339 out.writeObject(unit);
340 }
341
342 static SimplePeriod readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
343 long amount = in.readLong();
344 TemporalUnit unit = (TemporalUnit) in.readObject();
345 return SimplePeriod.of(amount, unit);
346 }
347
348 }