1 /* 2 * Copyright (c) 2012, 2015, 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; 63 64 import static java.time.temporal.ChronoField.ERA; 65 import static java.time.temporal.ChronoField.MONTH_OF_YEAR; 66 import static java.time.temporal.ChronoField.PROLEPTIC_MONTH; 67 import static java.time.temporal.ChronoField.YEAR; 68 import static java.time.temporal.ChronoField.YEAR_OF_ERA; 69 import static java.time.temporal.ChronoUnit.CENTURIES; 70 import static java.time.temporal.ChronoUnit.DECADES; 71 import static java.time.temporal.ChronoUnit.ERAS; 72 import static java.time.temporal.ChronoUnit.MILLENNIA; 73 import static java.time.temporal.ChronoUnit.MONTHS; 74 import static java.time.temporal.ChronoUnit.YEARS; 75 76 import java.io.DataInput; 77 import java.io.DataOutput; 78 import java.io.IOException; 79 import java.io.InvalidObjectException; 80 import java.io.ObjectInputStream; 81 import java.io.Serializable; 82 import java.time.chrono.Chronology; 83 import java.time.chrono.IsoChronology; 84 import java.time.format.DateTimeFormatter; 85 import java.time.format.DateTimeFormatterBuilder; 86 import java.time.format.DateTimeParseException; 87 import java.time.format.SignStyle; 88 import java.time.temporal.ChronoField; 89 import java.time.temporal.ChronoUnit; 90 import java.time.temporal.Temporal; 91 import java.time.temporal.TemporalAccessor; 92 import java.time.temporal.TemporalAdjuster; 93 import java.time.temporal.TemporalAmount; 94 import java.time.temporal.TemporalField; 95 import java.time.temporal.TemporalQueries; 96 import java.time.temporal.TemporalQuery; 97 import java.time.temporal.TemporalUnit; 98 import java.time.temporal.UnsupportedTemporalTypeException; 99 import java.time.temporal.ValueRange; 100 import java.util.Objects; 101 102 /** 103 * A year-month in the ISO-8601 calendar system, such as {@code 2007-12}. 104 * <p> 105 * {@code YearMonth} is an immutable date-time object that represents the combination 106 * of a year and month. Any field that can be derived from a year and month, such as 107 * quarter-of-year, can be obtained. 108 * <p> 109 * This class does not store or represent a day, time or time-zone. 110 * For example, the value "October 2007" can be stored in a {@code YearMonth}. 111 * <p> 112 * The ISO-8601 calendar system is the modern civil calendar system used today 113 * in most of the world. It is equivalent to the proleptic Gregorian calendar 114 * system, in which today's rules for leap years are applied for all time. 115 * For most applications written today, the ISO-8601 rules are entirely suitable. 116 * However, any application that makes use of historical dates, and requires them 117 * to be accurate will find the ISO-8601 approach unsuitable. 118 * 119 * <p> 120 * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a> 121 * class; use of identity-sensitive operations (including reference equality 122 * ({@code ==}), identity hash code, or synchronization) on instances of 123 * {@code YearMonth} may have unpredictable results and should be avoided. 124 * The {@code equals} method should be used for comparisons. 125 * 126 * @implSpec 127 * This class is immutable and thread-safe. 128 * 129 * @since 1.8 130 */ 131 public final class YearMonth 132 implements Temporal, TemporalAdjuster, Comparable<YearMonth>, Serializable { 133 134 /** 135 * Serialization version. 136 */ 137 private static final long serialVersionUID = 4183400860270640070L; 138 /** 139 * Parser. 140 */ 141 private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder() 142 .appendValue(YEAR, 4, 10, SignStyle.EXCEEDS_PAD) 143 .appendLiteral('-') 144 .appendValue(MONTH_OF_YEAR, 2) 145 .toFormatter(); 146 147 /** 148 * The year. 149 */ 150 private final int year; 151 /** 152 * The month-of-year, not null. 153 */ 154 private final int month; 155 156 //----------------------------------------------------------------------- 157 /** 158 * Obtains the current year-month from the system clock in the default time-zone. 159 * <p> 160 * This will query the {@link Clock#systemDefaultZone() system clock} in the default 161 * time-zone to obtain the current year-month. 162 * <p> 163 * Using this method will prevent the ability to use an alternate clock for testing 164 * because the clock is hard-coded. 165 * 166 * @return the current year-month using the system clock and default time-zone, not null 167 */ now()168 public static YearMonth now() { 169 return now(Clock.systemDefaultZone()); 170 } 171 172 /** 173 * Obtains the current year-month from the system clock in the specified time-zone. 174 * <p> 175 * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current year-month. 176 * Specifying the time-zone avoids dependence on the default time-zone. 177 * <p> 178 * Using this method will prevent the ability to use an alternate clock for testing 179 * because the clock is hard-coded. 180 * 181 * @param zone the zone ID to use, not null 182 * @return the current year-month using the system clock, not null 183 */ now(ZoneId zone)184 public static YearMonth now(ZoneId zone) { 185 return now(Clock.system(zone)); 186 } 187 188 /** 189 * Obtains the current year-month from the specified clock. 190 * <p> 191 * This will query the specified clock to obtain the current year-month. 192 * Using this method allows the use of an alternate clock for testing. 193 * The alternate clock may be introduced using {@link Clock dependency injection}. 194 * 195 * @param clock the clock to use, not null 196 * @return the current year-month, not null 197 */ now(Clock clock)198 public static YearMonth now(Clock clock) { 199 final LocalDate now = LocalDate.now(clock); // called once 200 return YearMonth.of(now.getYear(), now.getMonth()); 201 } 202 203 //----------------------------------------------------------------------- 204 /** 205 * Obtains an instance of {@code YearMonth} from a year and month. 206 * 207 * @param year the year to represent, from MIN_YEAR to MAX_YEAR 208 * @param month the month-of-year to represent, not null 209 * @return the year-month, not null 210 * @throws DateTimeException if the year value is invalid 211 */ of(int year, Month month)212 public static YearMonth of(int year, Month month) { 213 Objects.requireNonNull(month, "month"); 214 return of(year, month.getValue()); 215 } 216 217 /** 218 * Obtains an instance of {@code YearMonth} from a year and month. 219 * 220 * @param year the year to represent, from MIN_YEAR to MAX_YEAR 221 * @param month the month-of-year to represent, from 1 (January) to 12 (December) 222 * @return the year-month, not null 223 * @throws DateTimeException if either field value is invalid 224 */ of(int year, int month)225 public static YearMonth of(int year, int month) { 226 YEAR.checkValidValue(year); 227 MONTH_OF_YEAR.checkValidValue(month); 228 return new YearMonth(year, month); 229 } 230 231 //----------------------------------------------------------------------- 232 /** 233 * Obtains an instance of {@code YearMonth} from a temporal object. 234 * <p> 235 * This obtains a year-month based on the specified temporal. 236 * A {@code TemporalAccessor} represents an arbitrary set of date and time information, 237 * which this factory converts to an instance of {@code YearMonth}. 238 * <p> 239 * The conversion extracts the {@link ChronoField#YEAR YEAR} and 240 * {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} fields. 241 * The extraction is only permitted if the temporal object has an ISO 242 * chronology, or can be converted to a {@code LocalDate}. 243 * <p> 244 * This method matches the signature of the functional interface {@link TemporalQuery} 245 * allowing it to be used as a query via method reference, {@code YearMonth::from}. 246 * 247 * @param temporal the temporal object to convert, not null 248 * @return the year-month, not null 249 * @throws DateTimeException if unable to convert to a {@code YearMonth} 250 */ from(TemporalAccessor temporal)251 public static YearMonth from(TemporalAccessor temporal) { 252 if (temporal instanceof YearMonth) { 253 return (YearMonth) temporal; 254 } 255 Objects.requireNonNull(temporal, "temporal"); 256 try { 257 if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) { 258 temporal = LocalDate.from(temporal); 259 } 260 return of(temporal.get(YEAR), temporal.get(MONTH_OF_YEAR)); 261 } catch (DateTimeException ex) { 262 throw new DateTimeException("Unable to obtain YearMonth from TemporalAccessor: " + 263 temporal + " of type " + temporal.getClass().getName(), ex); 264 } 265 } 266 267 //----------------------------------------------------------------------- 268 /** 269 * Obtains an instance of {@code YearMonth} from a text string such as {@code 2007-12}. 270 * <p> 271 * The string must represent a valid year-month. 272 * The format must be {@code uuuu-MM}. 273 * Years outside the range 0000 to 9999 must be prefixed by the plus or minus symbol. 274 * 275 * @param text the text to parse such as "2007-12", not null 276 * @return the parsed year-month, not null 277 * @throws DateTimeParseException if the text cannot be parsed 278 */ parse(CharSequence text)279 public static YearMonth parse(CharSequence text) { 280 return parse(text, PARSER); 281 } 282 283 /** 284 * Obtains an instance of {@code YearMonth} from a text string using a specific formatter. 285 * <p> 286 * The text is parsed using the formatter, returning a year-month. 287 * 288 * @param text the text to parse, not null 289 * @param formatter the formatter to use, not null 290 * @return the parsed year-month, not null 291 * @throws DateTimeParseException if the text cannot be parsed 292 */ parse(CharSequence text, DateTimeFormatter formatter)293 public static YearMonth parse(CharSequence text, DateTimeFormatter formatter) { 294 Objects.requireNonNull(formatter, "formatter"); 295 return formatter.parse(text, YearMonth::from); 296 } 297 298 //----------------------------------------------------------------------- 299 /** 300 * Constructor. 301 * 302 * @param year the year to represent, validated from MIN_YEAR to MAX_YEAR 303 * @param month the month-of-year to represent, validated from 1 (January) to 12 (December) 304 */ YearMonth(int year, int month)305 private YearMonth(int year, int month) { 306 this.year = year; 307 this.month = month; 308 } 309 310 /** 311 * Returns a copy of this year-month with the new year and month, checking 312 * to see if a new object is in fact required. 313 * 314 * @param newYear the year to represent, validated from MIN_YEAR to MAX_YEAR 315 * @param newMonth the month-of-year to represent, validated not null 316 * @return the year-month, not null 317 */ with(int newYear, int newMonth)318 private YearMonth with(int newYear, int newMonth) { 319 if (year == newYear && month == newMonth) { 320 return this; 321 } 322 return new YearMonth(newYear, newMonth); 323 } 324 325 //----------------------------------------------------------------------- 326 /** 327 * Checks if the specified field is supported. 328 * <p> 329 * This checks if this year-month can be queried for the specified field. 330 * If false, then calling the {@link #range(TemporalField) range}, 331 * {@link #get(TemporalField) get} and {@link #with(TemporalField, long)} 332 * methods will throw an exception. 333 * <p> 334 * If the field is a {@link ChronoField} then the query is implemented here. 335 * The supported fields are: 336 * <ul> 337 * <li>{@code MONTH_OF_YEAR} 338 * <li>{@code PROLEPTIC_MONTH} 339 * <li>{@code YEAR_OF_ERA} 340 * <li>{@code YEAR} 341 * <li>{@code ERA} 342 * </ul> 343 * All other {@code ChronoField} instances will return false. 344 * <p> 345 * If the field is not a {@code ChronoField}, then the result of this method 346 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)} 347 * passing {@code this} as the argument. 348 * Whether the field is supported is determined by the field. 349 * 350 * @param field the field to check, null returns false 351 * @return true if the field is supported on this year-month, false if not 352 */ 353 @Override isSupported(TemporalField field)354 public boolean isSupported(TemporalField field) { 355 if (field instanceof ChronoField) { 356 return field == YEAR || field == MONTH_OF_YEAR || 357 field == PROLEPTIC_MONTH || field == YEAR_OF_ERA || field == ERA; 358 } 359 return field != null && field.isSupportedBy(this); 360 } 361 362 /** 363 * Checks if the specified unit is supported. 364 * <p> 365 * This checks if the specified unit can be added to, or subtracted from, this year-month. 366 * If false, then calling the {@link #plus(long, TemporalUnit)} and 367 * {@link #minus(long, TemporalUnit) minus} methods will throw an exception. 368 * <p> 369 * If the unit is a {@link ChronoUnit} then the query is implemented here. 370 * The supported units are: 371 * <ul> 372 * <li>{@code MONTHS} 373 * <li>{@code YEARS} 374 * <li>{@code DECADES} 375 * <li>{@code CENTURIES} 376 * <li>{@code MILLENNIA} 377 * <li>{@code ERAS} 378 * </ul> 379 * All other {@code ChronoUnit} instances will return false. 380 * <p> 381 * If the unit is not a {@code ChronoUnit}, then the result of this method 382 * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)} 383 * passing {@code this} as the argument. 384 * Whether the unit is supported is determined by the unit. 385 * 386 * @param unit the unit to check, null returns false 387 * @return true if the unit can be added/subtracted, false if not 388 */ 389 @Override isSupported(TemporalUnit unit)390 public boolean isSupported(TemporalUnit unit) { 391 if (unit instanceof ChronoUnit) { 392 return unit == MONTHS || unit == YEARS || unit == DECADES || unit == CENTURIES || unit == MILLENNIA || unit == ERAS; 393 } 394 return unit != null && unit.isSupportedBy(this); 395 } 396 397 //----------------------------------------------------------------------- 398 /** 399 * Gets the range of valid values for the specified field. 400 * <p> 401 * The range object expresses the minimum and maximum valid values for a field. 402 * This year-month is used to enhance the accuracy of the returned range. 403 * If it is not possible to return the range, because the field is not supported 404 * or for some other reason, an exception is thrown. 405 * <p> 406 * If the field is a {@link ChronoField} then the query is implemented here. 407 * The {@link #isSupported(TemporalField) supported fields} will return 408 * appropriate range instances. 409 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. 410 * <p> 411 * If the field is not a {@code ChronoField}, then the result of this method 412 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)} 413 * passing {@code this} as the argument. 414 * Whether the range can be obtained is determined by the field. 415 * 416 * @param field the field to query the range for, not null 417 * @return the range of valid values for the field, not null 418 * @throws DateTimeException if the range for the field cannot be obtained 419 * @throws UnsupportedTemporalTypeException if the field is not supported 420 */ 421 @Override range(TemporalField field)422 public ValueRange range(TemporalField field) { 423 if (field == YEAR_OF_ERA) { 424 return (getYear() <= 0 ? ValueRange.of(1, Year.MAX_VALUE + 1) : ValueRange.of(1, Year.MAX_VALUE)); 425 } 426 return Temporal.super.range(field); 427 } 428 429 /** 430 * Gets the value of the specified field from this year-month as an {@code int}. 431 * <p> 432 * This queries this year-month for the value of the specified field. 433 * The returned value will always be within the valid range of values for the field. 434 * If it is not possible to return the value, because the field is not supported 435 * or for some other reason, an exception is thrown. 436 * <p> 437 * If the field is a {@link ChronoField} then the query is implemented here. 438 * The {@link #isSupported(TemporalField) supported fields} will return valid 439 * values based on this year-month, except {@code PROLEPTIC_MONTH} which is too 440 * large to fit in an {@code int} and throw a {@code DateTimeException}. 441 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. 442 * <p> 443 * If the field is not a {@code ChronoField}, then the result of this method 444 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} 445 * passing {@code this} as the argument. Whether the value can be obtained, 446 * and what the value represents, is determined by the field. 447 * 448 * @param field the field to get, not null 449 * @return the value for the field 450 * @throws DateTimeException if a value for the field cannot be obtained or 451 * the value is outside the range of valid values for the field 452 * @throws UnsupportedTemporalTypeException if the field is not supported or 453 * the range of values exceeds an {@code int} 454 * @throws ArithmeticException if numeric overflow occurs 455 */ 456 @Override // override for Javadoc get(TemporalField field)457 public int get(TemporalField field) { 458 return range(field).checkValidIntValue(getLong(field), field); 459 } 460 461 /** 462 * Gets the value of the specified field from this year-month as a {@code long}. 463 * <p> 464 * This queries this year-month for the value of the specified field. 465 * If it is not possible to return the value, because the field is not supported 466 * or for some other reason, an exception is thrown. 467 * <p> 468 * If the field is a {@link ChronoField} then the query is implemented here. 469 * The {@link #isSupported(TemporalField) supported fields} will return valid 470 * values based on this year-month. 471 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. 472 * <p> 473 * If the field is not a {@code ChronoField}, then the result of this method 474 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} 475 * passing {@code this} as the argument. Whether the value can be obtained, 476 * and what the value represents, is determined by the field. 477 * 478 * @param field the field to get, not null 479 * @return the value for the field 480 * @throws DateTimeException if a value for the field cannot be obtained 481 * @throws UnsupportedTemporalTypeException if the field is not supported 482 * @throws ArithmeticException if numeric overflow occurs 483 */ 484 @Override getLong(TemporalField field)485 public long getLong(TemporalField field) { 486 if (field instanceof ChronoField) { 487 switch ((ChronoField) field) { 488 case MONTH_OF_YEAR: return month; 489 case PROLEPTIC_MONTH: return getProlepticMonth(); 490 case YEAR_OF_ERA: return (year < 1 ? 1 - year : year); 491 case YEAR: return year; 492 case ERA: return (year < 1 ? 0 : 1); 493 } 494 throw new UnsupportedTemporalTypeException("Unsupported field: " + field); 495 } 496 return field.getFrom(this); 497 } 498 getProlepticMonth()499 private long getProlepticMonth() { 500 return (year * 12L + month - 1); 501 } 502 503 //----------------------------------------------------------------------- 504 /** 505 * Gets the year field. 506 * <p> 507 * This method returns the primitive {@code int} value for the year. 508 * <p> 509 * The year returned by this method is proleptic as per {@code get(YEAR)}. 510 * 511 * @return the year, from MIN_YEAR to MAX_YEAR 512 */ getYear()513 public int getYear() { 514 return year; 515 } 516 517 /** 518 * Gets the month-of-year field from 1 to 12. 519 * <p> 520 * This method returns the month as an {@code int} from 1 to 12. 521 * Application code is frequently clearer if the enum {@link Month} 522 * is used by calling {@link #getMonth()}. 523 * 524 * @return the month-of-year, from 1 to 12 525 * @see #getMonth() 526 */ getMonthValue()527 public int getMonthValue() { 528 return month; 529 } 530 531 /** 532 * Gets the month-of-year field using the {@code Month} enum. 533 * <p> 534 * This method returns the enum {@link Month} for the month. 535 * This avoids confusion as to what {@code int} values mean. 536 * If you need access to the primitive {@code int} value then the enum 537 * provides the {@link Month#getValue() int value}. 538 * 539 * @return the month-of-year, not null 540 * @see #getMonthValue() 541 */ getMonth()542 public Month getMonth() { 543 return Month.of(month); 544 } 545 546 //----------------------------------------------------------------------- 547 /** 548 * Checks if the year is a leap year, according to the ISO proleptic 549 * calendar system rules. 550 * <p> 551 * This method applies the current rules for leap years across the whole time-line. 552 * In general, a year is a leap year if it is divisible by four without 553 * remainder. However, years divisible by 100, are not leap years, with 554 * the exception of years divisible by 400 which are. 555 * <p> 556 * For example, 1904 is a leap year it is divisible by 4. 557 * 1900 was not a leap year as it is divisible by 100, however 2000 was a 558 * leap year as it is divisible by 400. 559 * <p> 560 * The calculation is proleptic - applying the same rules into the far future and far past. 561 * This is historically inaccurate, but is correct for the ISO-8601 standard. 562 * 563 * @return true if the year is leap, false otherwise 564 */ isLeapYear()565 public boolean isLeapYear() { 566 return IsoChronology.INSTANCE.isLeapYear(year); 567 } 568 569 /** 570 * Checks if the day-of-month is valid for this year-month. 571 * <p> 572 * This method checks whether this year and month and the input day form 573 * a valid date. 574 * 575 * @param dayOfMonth the day-of-month to validate, from 1 to 31, invalid value returns false 576 * @return true if the day is valid for this year-month 577 */ isValidDay(int dayOfMonth)578 public boolean isValidDay(int dayOfMonth) { 579 return dayOfMonth >= 1 && dayOfMonth <= lengthOfMonth(); 580 } 581 582 /** 583 * Returns the length of the month, taking account of the year. 584 * <p> 585 * This returns the length of the month in days. 586 * For example, a date in January would return 31. 587 * 588 * @return the length of the month in days, from 28 to 31 589 */ lengthOfMonth()590 public int lengthOfMonth() { 591 return getMonth().length(isLeapYear()); 592 } 593 594 /** 595 * Returns the length of the year. 596 * <p> 597 * This returns the length of the year in days, either 365 or 366. 598 * 599 * @return 366 if the year is leap, 365 otherwise 600 */ lengthOfYear()601 public int lengthOfYear() { 602 return (isLeapYear() ? 366 : 365); 603 } 604 605 //----------------------------------------------------------------------- 606 /** 607 * Returns an adjusted copy of this year-month. 608 * <p> 609 * This returns a {@code YearMonth}, based on this one, with the year-month adjusted. 610 * The adjustment takes place using the specified adjuster strategy object. 611 * Read the documentation of the adjuster to understand what adjustment will be made. 612 * <p> 613 * A simple adjuster might simply set the one of the fields, such as the year field. 614 * A more complex adjuster might set the year-month to the next month that 615 * Halley's comet will pass the Earth. 616 * <p> 617 * The result of this method is obtained by invoking the 618 * {@link TemporalAdjuster#adjustInto(Temporal)} method on the 619 * specified adjuster passing {@code this} as the argument. 620 * <p> 621 * This instance is immutable and unaffected by this method call. 622 * 623 * @param adjuster the adjuster to use, not null 624 * @return a {@code YearMonth} based on {@code this} with the adjustment made, not null 625 * @throws DateTimeException if the adjustment cannot be made 626 * @throws ArithmeticException if numeric overflow occurs 627 */ 628 @Override with(TemporalAdjuster adjuster)629 public YearMonth with(TemporalAdjuster adjuster) { 630 return (YearMonth) adjuster.adjustInto(this); 631 } 632 633 /** 634 * Returns a copy of this year-month with the specified field set to a new value. 635 * <p> 636 * This returns a {@code YearMonth}, based on this one, with the value 637 * for the specified field changed. 638 * This can be used to change any supported field, such as the year or month. 639 * If it is not possible to set the value, because the field is not supported or for 640 * some other reason, an exception is thrown. 641 * <p> 642 * If the field is a {@link ChronoField} then the adjustment is implemented here. 643 * The supported fields behave as follows: 644 * <ul> 645 * <li>{@code MONTH_OF_YEAR} - 646 * Returns a {@code YearMonth} with the specified month-of-year. 647 * The year will be unchanged. 648 * <li>{@code PROLEPTIC_MONTH} - 649 * Returns a {@code YearMonth} with the specified proleptic-month. 650 * This completely replaces the year and month of this object. 651 * <li>{@code YEAR_OF_ERA} - 652 * Returns a {@code YearMonth} with the specified year-of-era 653 * The month and era will be unchanged. 654 * <li>{@code YEAR} - 655 * Returns a {@code YearMonth} with the specified year. 656 * The month will be unchanged. 657 * <li>{@code ERA} - 658 * Returns a {@code YearMonth} with the specified era. 659 * The month and year-of-era will be unchanged. 660 * </ul> 661 * <p> 662 * In all cases, if the new value is outside the valid range of values for the field 663 * then a {@code DateTimeException} will be thrown. 664 * <p> 665 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. 666 * <p> 667 * If the field is not a {@code ChronoField}, then the result of this method 668 * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)} 669 * passing {@code this} as the argument. In this case, the field determines 670 * whether and how to adjust the instant. 671 * <p> 672 * This instance is immutable and unaffected by this method call. 673 * 674 * @param field the field to set in the result, not null 675 * @param newValue the new value of the field in the result 676 * @return a {@code YearMonth} based on {@code this} with the specified field set, not null 677 * @throws DateTimeException if the field cannot be set 678 * @throws UnsupportedTemporalTypeException if the field is not supported 679 * @throws ArithmeticException if numeric overflow occurs 680 */ 681 @Override with(TemporalField field, long newValue)682 public YearMonth with(TemporalField field, long newValue) { 683 if (field instanceof ChronoField) { 684 ChronoField f = (ChronoField) field; 685 f.checkValidValue(newValue); 686 switch (f) { 687 case MONTH_OF_YEAR: return withMonth((int) newValue); 688 case PROLEPTIC_MONTH: return plusMonths(newValue - getProlepticMonth()); 689 case YEAR_OF_ERA: return withYear((int) (year < 1 ? 1 - newValue : newValue)); 690 case YEAR: return withYear((int) newValue); 691 case ERA: return (getLong(ERA) == newValue ? this : withYear(1 - year)); 692 } 693 throw new UnsupportedTemporalTypeException("Unsupported field: " + field); 694 } 695 return field.adjustInto(this, newValue); 696 } 697 698 //----------------------------------------------------------------------- 699 /** 700 * Returns a copy of this {@code YearMonth} with the year altered. 701 * <p> 702 * This instance is immutable and unaffected by this method call. 703 * 704 * @param year the year to set in the returned year-month, from MIN_YEAR to MAX_YEAR 705 * @return a {@code YearMonth} based on this year-month with the requested year, not null 706 * @throws DateTimeException if the year value is invalid 707 */ withYear(int year)708 public YearMonth withYear(int year) { 709 YEAR.checkValidValue(year); 710 return with(year, month); 711 } 712 713 /** 714 * Returns a copy of this {@code YearMonth} with the month-of-year altered. 715 * <p> 716 * This instance is immutable and unaffected by this method call. 717 * 718 * @param month the month-of-year to set in the returned year-month, from 1 (January) to 12 (December) 719 * @return a {@code YearMonth} based on this year-month with the requested month, not null 720 * @throws DateTimeException if the month-of-year value is invalid 721 */ withMonth(int month)722 public YearMonth withMonth(int month) { 723 MONTH_OF_YEAR.checkValidValue(month); 724 return with(year, month); 725 } 726 727 //----------------------------------------------------------------------- 728 /** 729 * Returns a copy of this year-month with the specified amount added. 730 * <p> 731 * This returns a {@code YearMonth}, based on this one, with the specified amount added. 732 * The amount is typically {@link Period} but may be any other type implementing 733 * the {@link TemporalAmount} interface. 734 * <p> 735 * The calculation is delegated to the amount object by calling 736 * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free 737 * to implement the addition in any way it wishes, however it typically 738 * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation 739 * of the amount implementation to determine if it can be successfully added. 740 * <p> 741 * This instance is immutable and unaffected by this method call. 742 * 743 * @param amountToAdd the amount to add, not null 744 * @return a {@code YearMonth} based on this year-month with the addition made, not null 745 * @throws DateTimeException if the addition cannot be made 746 * @throws ArithmeticException if numeric overflow occurs 747 */ 748 @Override plus(TemporalAmount amountToAdd)749 public YearMonth plus(TemporalAmount amountToAdd) { 750 return (YearMonth) amountToAdd.addTo(this); 751 } 752 753 /** 754 * Returns a copy of this year-month with the specified amount added. 755 * <p> 756 * This returns a {@code YearMonth}, based on this one, with the amount 757 * in terms of the unit added. If it is not possible to add the amount, because the 758 * unit is not supported or for some other reason, an exception is thrown. 759 * <p> 760 * If the field is a {@link ChronoUnit} then the addition is implemented here. 761 * The supported fields behave as follows: 762 * <ul> 763 * <li>{@code MONTHS} - 764 * Returns a {@code YearMonth} with the specified number of months added. 765 * This is equivalent to {@link #plusMonths(long)}. 766 * <li>{@code YEARS} - 767 * Returns a {@code YearMonth} with the specified number of years added. 768 * This is equivalent to {@link #plusYears(long)}. 769 * <li>{@code DECADES} - 770 * Returns a {@code YearMonth} with the specified number of decades added. 771 * This is equivalent to calling {@link #plusYears(long)} with the amount 772 * multiplied by 10. 773 * <li>{@code CENTURIES} - 774 * Returns a {@code YearMonth} with the specified number of centuries added. 775 * This is equivalent to calling {@link #plusYears(long)} with the amount 776 * multiplied by 100. 777 * <li>{@code MILLENNIA} - 778 * Returns a {@code YearMonth} with the specified number of millennia added. 779 * This is equivalent to calling {@link #plusYears(long)} with the amount 780 * multiplied by 1,000. 781 * <li>{@code ERAS} - 782 * Returns a {@code YearMonth} with the specified number of eras added. 783 * Only two eras are supported so the amount must be one, zero or minus one. 784 * If the amount is non-zero then the year is changed such that the year-of-era 785 * is unchanged. 786 * </ul> 787 * <p> 788 * All other {@code ChronoUnit} instances will throw an {@code UnsupportedTemporalTypeException}. 789 * <p> 790 * If the field is not a {@code ChronoUnit}, then the result of this method 791 * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)} 792 * passing {@code this} as the argument. In this case, the unit determines 793 * whether and how to perform the addition. 794 * <p> 795 * This instance is immutable and unaffected by this method call. 796 * 797 * @param amountToAdd the amount of the unit to add to the result, may be negative 798 * @param unit the unit of the amount to add, not null 799 * @return a {@code YearMonth} based on this year-month with the specified amount added, not null 800 * @throws DateTimeException if the addition cannot be made 801 * @throws UnsupportedTemporalTypeException if the unit is not supported 802 * @throws ArithmeticException if numeric overflow occurs 803 */ 804 @Override plus(long amountToAdd, TemporalUnit unit)805 public YearMonth plus(long amountToAdd, TemporalUnit unit) { 806 if (unit instanceof ChronoUnit) { 807 switch ((ChronoUnit) unit) { 808 case MONTHS: return plusMonths(amountToAdd); 809 case YEARS: return plusYears(amountToAdd); 810 case DECADES: return plusYears(Math.multiplyExact(amountToAdd, 10)); 811 case CENTURIES: return plusYears(Math.multiplyExact(amountToAdd, 100)); 812 case MILLENNIA: return plusYears(Math.multiplyExact(amountToAdd, 1000)); 813 case ERAS: return with(ERA, Math.addExact(getLong(ERA), amountToAdd)); 814 } 815 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit); 816 } 817 return unit.addTo(this, amountToAdd); 818 } 819 820 /** 821 * Returns a copy of this {@code YearMonth} with the specified number of years added. 822 * <p> 823 * This instance is immutable and unaffected by this method call. 824 * 825 * @param yearsToAdd the years to add, may be negative 826 * @return a {@code YearMonth} based on this year-month with the years added, not null 827 * @throws DateTimeException if the result exceeds the supported range 828 */ plusYears(long yearsToAdd)829 public YearMonth plusYears(long yearsToAdd) { 830 if (yearsToAdd == 0) { 831 return this; 832 } 833 int newYear = YEAR.checkValidIntValue(year + yearsToAdd); // safe overflow 834 return with(newYear, month); 835 } 836 837 /** 838 * Returns a copy of this {@code YearMonth} with the specified number of months added. 839 * <p> 840 * This instance is immutable and unaffected by this method call. 841 * 842 * @param monthsToAdd the months to add, may be negative 843 * @return a {@code YearMonth} based on this year-month with the months added, not null 844 * @throws DateTimeException if the result exceeds the supported range 845 */ plusMonths(long monthsToAdd)846 public YearMonth plusMonths(long monthsToAdd) { 847 if (monthsToAdd == 0) { 848 return this; 849 } 850 long monthCount = year * 12L + (month - 1); 851 long calcMonths = monthCount + monthsToAdd; // safe overflow 852 int newYear = YEAR.checkValidIntValue(Math.floorDiv(calcMonths, 12)); 853 int newMonth = (int)Math.floorMod(calcMonths, 12) + 1; 854 return with(newYear, newMonth); 855 } 856 857 //----------------------------------------------------------------------- 858 /** 859 * Returns a copy of this year-month with the specified amount subtracted. 860 * <p> 861 * This returns a {@code YearMonth}, based on this one, with the specified amount subtracted. 862 * The amount is typically {@link Period} but may be any other type implementing 863 * the {@link TemporalAmount} interface. 864 * <p> 865 * The calculation is delegated to the amount object by calling 866 * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free 867 * to implement the subtraction in any way it wishes, however it typically 868 * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation 869 * of the amount implementation to determine if it can be successfully subtracted. 870 * <p> 871 * This instance is immutable and unaffected by this method call. 872 * 873 * @param amountToSubtract the amount to subtract, not null 874 * @return a {@code YearMonth} based on this year-month with the subtraction made, not null 875 * @throws DateTimeException if the subtraction cannot be made 876 * @throws ArithmeticException if numeric overflow occurs 877 */ 878 @Override minus(TemporalAmount amountToSubtract)879 public YearMonth minus(TemporalAmount amountToSubtract) { 880 return (YearMonth) amountToSubtract.subtractFrom(this); 881 } 882 883 /** 884 * Returns a copy of this year-month with the specified amount subtracted. 885 * <p> 886 * This returns a {@code YearMonth}, based on this one, with the amount 887 * in terms of the unit subtracted. If it is not possible to subtract the amount, 888 * because the unit is not supported or for some other reason, an exception is thrown. 889 * <p> 890 * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated. 891 * See that method for a full description of how addition, and thus subtraction, works. 892 * <p> 893 * This instance is immutable and unaffected by this method call. 894 * 895 * @param amountToSubtract the amount of the unit to subtract from the result, may be negative 896 * @param unit the unit of the amount to subtract, not null 897 * @return a {@code YearMonth} based on this year-month with the specified amount subtracted, not null 898 * @throws DateTimeException if the subtraction cannot be made 899 * @throws UnsupportedTemporalTypeException if the unit is not supported 900 * @throws ArithmeticException if numeric overflow occurs 901 */ 902 @Override minus(long amountToSubtract, TemporalUnit unit)903 public YearMonth minus(long amountToSubtract, TemporalUnit unit) { 904 return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit)); 905 } 906 907 /** 908 * Returns a copy of this {@code YearMonth} with the specified number of years subtracted. 909 * <p> 910 * This instance is immutable and unaffected by this method call. 911 * 912 * @param yearsToSubtract the years to subtract, may be negative 913 * @return a {@code YearMonth} based on this year-month with the years subtracted, not null 914 * @throws DateTimeException if the result exceeds the supported range 915 */ minusYears(long yearsToSubtract)916 public YearMonth minusYears(long yearsToSubtract) { 917 return (yearsToSubtract == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-yearsToSubtract)); 918 } 919 920 /** 921 * Returns a copy of this {@code YearMonth} with the specified number of months subtracted. 922 * <p> 923 * This instance is immutable and unaffected by this method call. 924 * 925 * @param monthsToSubtract the months to subtract, may be negative 926 * @return a {@code YearMonth} based on this year-month with the months subtracted, not null 927 * @throws DateTimeException if the result exceeds the supported range 928 */ minusMonths(long monthsToSubtract)929 public YearMonth minusMonths(long monthsToSubtract) { 930 return (monthsToSubtract == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-monthsToSubtract)); 931 } 932 933 //----------------------------------------------------------------------- 934 /** 935 * Queries this year-month using the specified query. 936 * <p> 937 * This queries this year-month using the specified query strategy object. 938 * The {@code TemporalQuery} object defines the logic to be used to 939 * obtain the result. Read the documentation of the query to understand 940 * what the result of this method will be. 941 * <p> 942 * The result of this method is obtained by invoking the 943 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the 944 * specified query passing {@code this} as the argument. 945 * 946 * @param <R> the type of the result 947 * @param query the query to invoke, not null 948 * @return the query result, null may be returned (defined by the query) 949 * @throws DateTimeException if unable to query (defined by the query) 950 * @throws ArithmeticException if numeric overflow occurs (defined by the query) 951 */ 952 @SuppressWarnings("unchecked") 953 @Override query(TemporalQuery<R> query)954 public <R> R query(TemporalQuery<R> query) { 955 if (query == TemporalQueries.chronology()) { 956 return (R) IsoChronology.INSTANCE; 957 } else if (query == TemporalQueries.precision()) { 958 return (R) MONTHS; 959 } 960 return Temporal.super.query(query); 961 } 962 963 /** 964 * Adjusts the specified temporal object to have this year-month. 965 * <p> 966 * This returns a temporal object of the same observable type as the input 967 * with the year and month changed to be the same as this. 968 * <p> 969 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)} 970 * passing {@link ChronoField#PROLEPTIC_MONTH} as the field. 971 * If the specified temporal object does not use the ISO calendar system then 972 * a {@code DateTimeException} is thrown. 973 * <p> 974 * In most cases, it is clearer to reverse the calling pattern by using 975 * {@link Temporal#with(TemporalAdjuster)}: 976 * <pre> 977 * // these two lines are equivalent, but the second approach is recommended 978 * temporal = thisYearMonth.adjustInto(temporal); 979 * temporal = temporal.with(thisYearMonth); 980 * </pre> 981 * <p> 982 * This instance is immutable and unaffected by this method call. 983 * 984 * @param temporal the target object to be adjusted, not null 985 * @return the adjusted object, not null 986 * @throws DateTimeException if unable to make the adjustment 987 * @throws ArithmeticException if numeric overflow occurs 988 */ 989 @Override adjustInto(Temporal temporal)990 public Temporal adjustInto(Temporal temporal) { 991 if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) { 992 throw new DateTimeException("Adjustment only supported on ISO date-time"); 993 } 994 return temporal.with(PROLEPTIC_MONTH, getProlepticMonth()); 995 } 996 997 /** 998 * Calculates the amount of time until another year-month in terms of the specified unit. 999 * <p> 1000 * This calculates the amount of time between two {@code YearMonth} 1001 * objects in terms of a single {@code TemporalUnit}. 1002 * The start and end points are {@code this} and the specified year-month. 1003 * The result will be negative if the end is before the start. 1004 * The {@code Temporal} passed to this method is converted to a 1005 * {@code YearMonth} using {@link #from(TemporalAccessor)}. 1006 * For example, the amount in years between two year-months can be calculated 1007 * using {@code startYearMonth.until(endYearMonth, YEARS)}. 1008 * <p> 1009 * The calculation returns a whole number, representing the number of 1010 * complete units between the two year-months. 1011 * For example, the amount in decades between 2012-06 and 2032-05 1012 * will only be one decade as it is one month short of two decades. 1013 * <p> 1014 * There are two equivalent ways of using this method. 1015 * The first is to invoke this method. 1016 * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}: 1017 * <pre> 1018 * // these two lines are equivalent 1019 * amount = start.until(end, MONTHS); 1020 * amount = MONTHS.between(start, end); 1021 * </pre> 1022 * The choice should be made based on which makes the code more readable. 1023 * <p> 1024 * The calculation is implemented in this method for {@link ChronoUnit}. 1025 * The units {@code MONTHS}, {@code YEARS}, {@code DECADES}, 1026 * {@code CENTURIES}, {@code MILLENNIA} and {@code ERAS} are supported. 1027 * Other {@code ChronoUnit} values will throw an exception. 1028 * <p> 1029 * If the unit is not a {@code ChronoUnit}, then the result of this method 1030 * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)} 1031 * passing {@code this} as the first argument and the converted input temporal 1032 * as the second argument. 1033 * <p> 1034 * This instance is immutable and unaffected by this method call. 1035 * 1036 * @param endExclusive the end date, exclusive, which is converted to a {@code YearMonth}, not null 1037 * @param unit the unit to measure the amount in, not null 1038 * @return the amount of time between this year-month and the end year-month 1039 * @throws DateTimeException if the amount cannot be calculated, or the end 1040 * temporal cannot be converted to a {@code YearMonth} 1041 * @throws UnsupportedTemporalTypeException if the unit is not supported 1042 * @throws ArithmeticException if numeric overflow occurs 1043 */ 1044 @Override until(Temporal endExclusive, TemporalUnit unit)1045 public long until(Temporal endExclusive, TemporalUnit unit) { 1046 YearMonth end = YearMonth.from(endExclusive); 1047 if (unit instanceof ChronoUnit) { 1048 long monthsUntil = end.getProlepticMonth() - getProlepticMonth(); // no overflow 1049 switch ((ChronoUnit) unit) { 1050 case MONTHS: return monthsUntil; 1051 case YEARS: return monthsUntil / 12; 1052 case DECADES: return monthsUntil / 120; 1053 case CENTURIES: return monthsUntil / 1200; 1054 case MILLENNIA: return monthsUntil / 12000; 1055 case ERAS: return end.getLong(ERA) - getLong(ERA); 1056 } 1057 throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit); 1058 } 1059 return unit.between(this, end); 1060 } 1061 1062 /** 1063 * Formats this year-month using the specified formatter. 1064 * <p> 1065 * This year-month will be passed to the formatter to produce a string. 1066 * 1067 * @param formatter the formatter to use, not null 1068 * @return the formatted year-month string, not null 1069 * @throws DateTimeException if an error occurs during printing 1070 */ format(DateTimeFormatter formatter)1071 public String format(DateTimeFormatter formatter) { 1072 Objects.requireNonNull(formatter, "formatter"); 1073 return formatter.format(this); 1074 } 1075 1076 //----------------------------------------------------------------------- 1077 /** 1078 * Combines this year-month with a day-of-month to create a {@code LocalDate}. 1079 * <p> 1080 * This returns a {@code LocalDate} formed from this year-month and the specified day-of-month. 1081 * <p> 1082 * The day-of-month value must be valid for the year-month. 1083 * <p> 1084 * This method can be used as part of a chain to produce a date: 1085 * <pre> 1086 * LocalDate date = year.atMonth(month).atDay(day); 1087 * </pre> 1088 * 1089 * @param dayOfMonth the day-of-month to use, from 1 to 31 1090 * @return the date formed from this year-month and the specified day, not null 1091 * @throws DateTimeException if the day is invalid for the year-month 1092 * @see #isValidDay(int) 1093 */ atDay(int dayOfMonth)1094 public LocalDate atDay(int dayOfMonth) { 1095 return LocalDate.of(year, month, dayOfMonth); 1096 } 1097 1098 /** 1099 * Returns a {@code LocalDate} at the end of the month. 1100 * <p> 1101 * This returns a {@code LocalDate} based on this year-month. 1102 * The day-of-month is set to the last valid day of the month, taking 1103 * into account leap years. 1104 * <p> 1105 * This method can be used as part of a chain to produce a date: 1106 * <pre> 1107 * LocalDate date = year.atMonth(month).atEndOfMonth(); 1108 * </pre> 1109 * 1110 * @return the last valid date of this year-month, not null 1111 */ atEndOfMonth()1112 public LocalDate atEndOfMonth() { 1113 return LocalDate.of(year, month, lengthOfMonth()); 1114 } 1115 1116 //----------------------------------------------------------------------- 1117 /** 1118 * Compares this year-month to another year-month. 1119 * <p> 1120 * The comparison is based first on the value of the year, then on the value of the month. 1121 * It is "consistent with equals", as defined by {@link Comparable}. 1122 * 1123 * @param other the other year-month to compare to, not null 1124 * @return the comparator value, negative if less, positive if greater 1125 */ 1126 @Override compareTo(YearMonth other)1127 public int compareTo(YearMonth other) { 1128 int cmp = (year - other.year); 1129 if (cmp == 0) { 1130 cmp = (month - other.month); 1131 } 1132 return cmp; 1133 } 1134 1135 /** 1136 * Checks if this year-month is after the specified year-month. 1137 * 1138 * @param other the other year-month to compare to, not null 1139 * @return true if this is after the specified year-month 1140 */ isAfter(YearMonth other)1141 public boolean isAfter(YearMonth other) { 1142 return compareTo(other) > 0; 1143 } 1144 1145 /** 1146 * Checks if this year-month is before the specified year-month. 1147 * 1148 * @param other the other year-month to compare to, not null 1149 * @return true if this point is before the specified year-month 1150 */ isBefore(YearMonth other)1151 public boolean isBefore(YearMonth other) { 1152 return compareTo(other) < 0; 1153 } 1154 1155 //----------------------------------------------------------------------- 1156 /** 1157 * Checks if this year-month is equal to another year-month. 1158 * <p> 1159 * The comparison is based on the time-line position of the year-months. 1160 * 1161 * @param obj the object to check, null returns false 1162 * @return true if this is equal to the other year-month 1163 */ 1164 @Override equals(Object obj)1165 public boolean equals(Object obj) { 1166 if (this == obj) { 1167 return true; 1168 } 1169 if (obj instanceof YearMonth) { 1170 YearMonth other = (YearMonth) obj; 1171 return year == other.year && month == other.month; 1172 } 1173 return false; 1174 } 1175 1176 /** 1177 * A hash code for this year-month. 1178 * 1179 * @return a suitable hash code 1180 */ 1181 @Override hashCode()1182 public int hashCode() { 1183 return year ^ (month << 27); 1184 } 1185 1186 //----------------------------------------------------------------------- 1187 /** 1188 * Outputs this year-month as a {@code String}, such as {@code 2007-12}. 1189 * <p> 1190 * The output will be in the format {@code uuuu-MM}: 1191 * 1192 * @return a string representation of this year-month, not null 1193 */ 1194 @Override toString()1195 public String toString() { 1196 int absYear = Math.abs(year); 1197 StringBuilder buf = new StringBuilder(9); 1198 if (absYear < 1000) { 1199 if (year < 0) { 1200 buf.append(year - 10000).deleteCharAt(1); 1201 } else { 1202 buf.append(year + 10000).deleteCharAt(0); 1203 } 1204 } else { 1205 buf.append(year); 1206 } 1207 return buf.append(month < 10 ? "-0" : "-") 1208 .append(month) 1209 .toString(); 1210 } 1211 1212 //----------------------------------------------------------------------- 1213 /** 1214 * Writes the object using a 1215 * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>. 1216 * @serialData 1217 * <pre> 1218 * out.writeByte(12); // identifies a YearMonth 1219 * out.writeInt(year); 1220 * out.writeByte(month); 1221 * </pre> 1222 * 1223 * @return the instance of {@code Ser}, not null 1224 */ writeReplace()1225 private Object writeReplace() { 1226 return new Ser(Ser.YEAR_MONTH_TYPE, this); 1227 } 1228 1229 /** 1230 * Defend against malicious streams. 1231 * 1232 * @param s the stream to read 1233 * @throws InvalidObjectException always 1234 */ readObject(ObjectInputStream s)1235 private void readObject(ObjectInputStream s) throws InvalidObjectException { 1236 throw new InvalidObjectException("Deserialization via serialization delegate"); 1237 } 1238 writeExternal(DataOutput out)1239 void writeExternal(DataOutput out) throws IOException { 1240 out.writeInt(year); 1241 out.writeByte(month); 1242 } 1243 readExternal(DataInput in)1244 static YearMonth readExternal(DataInput in) throws IOException { 1245 int year = in.readInt(); 1246 byte month = in.readByte(); 1247 return YearMonth.of(year, month); 1248 } 1249 1250 } 1251