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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 */ 62package java.time; 63 64import static java.time.temporal.ChronoField.MONTH_OF_YEAR; 65import static java.time.temporal.ChronoUnit.MONTHS; 66 67import java.time.chrono.Chronology; 68import java.time.chrono.IsoChronology; 69import java.time.format.DateTimeFormatterBuilder; 70import java.time.format.TextStyle; 71import java.time.temporal.ChronoField; 72import java.time.temporal.Temporal; 73import java.time.temporal.TemporalAccessor; 74import java.time.temporal.TemporalAdjuster; 75import java.time.temporal.TemporalField; 76import java.time.temporal.TemporalQueries; 77import java.time.temporal.TemporalQuery; 78import java.time.temporal.UnsupportedTemporalTypeException; 79import java.time.temporal.ValueRange; 80import java.util.Locale; 81 82/** 83 * A month-of-year, such as 'July'. 84 * <p> 85 * {@code Month} is an enum representing the 12 months of the year - 86 * January, February, March, April, May, June, July, August, September, October, 87 * November and December. 88 * <p> 89 * In addition to the textual enum name, each month-of-year has an {@code int} value. 90 * The {@code int} value follows normal usage and the ISO-8601 standard, 91 * from 1 (January) to 12 (December). It is recommended that applications use the enum 92 * rather than the {@code int} value to ensure code clarity. 93 * <p> 94 * <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code Month}. 95 * Use {@code getValue()} instead.</b> 96 * <p> 97 * This enum represents a common concept that is found in many calendar systems. 98 * As such, this enum may be used by any calendar system that has the month-of-year 99 * concept defined exactly equivalent to the ISO-8601 calendar system. 100 * 101 * @implSpec 102 * This is an immutable and thread-safe enum. 103 * 104 * @since 1.8 105 */ 106public enum Month implements TemporalAccessor, TemporalAdjuster { 107 108 /** 109 * The singleton instance for the month of January with 31 days. 110 * This has the numeric value of {@code 1}. 111 */ 112 JANUARY, 113 /** 114 * The singleton instance for the month of February with 28 days, or 29 in a leap year. 115 * This has the numeric value of {@code 2}. 116 */ 117 FEBRUARY, 118 /** 119 * The singleton instance for the month of March with 31 days. 120 * This has the numeric value of {@code 3}. 121 */ 122 MARCH, 123 /** 124 * The singleton instance for the month of April with 30 days. 125 * This has the numeric value of {@code 4}. 126 */ 127 APRIL, 128 /** 129 * The singleton instance for the month of May with 31 days. 130 * This has the numeric value of {@code 5}. 131 */ 132 MAY, 133 /** 134 * The singleton instance for the month of June with 30 days. 135 * This has the numeric value of {@code 6}. 136 */ 137 JUNE, 138 /** 139 * The singleton instance for the month of July with 31 days. 140 * This has the numeric value of {@code 7}. 141 */ 142 JULY, 143 /** 144 * The singleton instance for the month of August with 31 days. 145 * This has the numeric value of {@code 8}. 146 */ 147 AUGUST, 148 /** 149 * The singleton instance for the month of September with 30 days. 150 * This has the numeric value of {@code 9}. 151 */ 152 SEPTEMBER, 153 /** 154 * The singleton instance for the month of October with 31 days. 155 * This has the numeric value of {@code 10}. 156 */ 157 OCTOBER, 158 /** 159 * The singleton instance for the month of November with 30 days. 160 * This has the numeric value of {@code 11}. 161 */ 162 NOVEMBER, 163 /** 164 * The singleton instance for the month of December with 31 days. 165 * This has the numeric value of {@code 12}. 166 */ 167 DECEMBER; 168 /** 169 * Private cache of all the constants. 170 */ 171 private static final Month[] ENUMS = Month.values(); 172 173 //----------------------------------------------------------------------- 174 /** 175 * Obtains an instance of {@code Month} from an {@code int} value. 176 * <p> 177 * {@code Month} is an enum representing the 12 months of the year. 178 * This factory allows the enum to be obtained from the {@code int} value. 179 * The {@code int} value follows the ISO-8601 standard, from 1 (January) to 12 (December). 180 * 181 * @param month the month-of-year to represent, from 1 (January) to 12 (December) 182 * @return the month-of-year, not null 183 * @throws DateTimeException if the month-of-year is invalid 184 */ 185 public static Month of(int month) { 186 if (month < 1 || month > 12) { 187 throw new DateTimeException("Invalid value for MonthOfYear: " + month); 188 } 189 return ENUMS[month - 1]; 190 } 191 192 //----------------------------------------------------------------------- 193 /** 194 * Obtains an instance of {@code Month} from a temporal object. 195 * <p> 196 * This obtains a month based on the specified temporal. 197 * A {@code TemporalAccessor} represents an arbitrary set of date and time information, 198 * which this factory converts to an instance of {@code Month}. 199 * <p> 200 * The conversion extracts the {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} field. 201 * The extraction is only permitted if the temporal object has an ISO 202 * chronology, or can be converted to a {@code LocalDate}. 203 * <p> 204 * This method matches the signature of the functional interface {@link TemporalQuery} 205 * allowing it to be used as a query via method reference, {@code Month::from}. 206 * 207 * @param temporal the temporal object to convert, not null 208 * @return the month-of-year, not null 209 * @throws DateTimeException if unable to convert to a {@code Month} 210 */ 211 public static Month from(TemporalAccessor temporal) { 212 if (temporal instanceof Month) { 213 return (Month) temporal; 214 } 215 try { 216 if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) { 217 temporal = LocalDate.from(temporal); 218 } 219 return of(temporal.get(MONTH_OF_YEAR)); 220 } catch (DateTimeException ex) { 221 throw new DateTimeException("Unable to obtain Month from TemporalAccessor: " + 222 temporal + " of type " + temporal.getClass().getName(), ex); 223 } 224 } 225 226 //----------------------------------------------------------------------- 227 /** 228 * Gets the month-of-year {@code int} value. 229 * <p> 230 * The values are numbered following the ISO-8601 standard, 231 * from 1 (January) to 12 (December). 232 * 233 * @return the month-of-year, from 1 (January) to 12 (December) 234 */ 235 public int getValue() { 236 return ordinal() + 1; 237 } 238 239 //----------------------------------------------------------------------- 240 /** 241 * Gets the textual representation, such as 'Jan' or 'December'. 242 * <p> 243 * This returns the textual name used to identify the month-of-year, 244 * suitable for presentation to the user. 245 * The parameters control the style of the returned text and the locale. 246 * <p> 247 * If no textual mapping is found then the {@link #getValue() numeric value} is returned. 248 * 249 * @param style the length of the text required, not null 250 * @param locale the locale to use, not null 251 * @return the text value of the month-of-year, not null 252 */ 253 public String getDisplayName(TextStyle style, Locale locale) { 254 return new DateTimeFormatterBuilder().appendText(MONTH_OF_YEAR, style).toFormatter(locale).format(this); 255 } 256 257 //----------------------------------------------------------------------- 258 /** 259 * Checks if the specified field is supported. 260 * <p> 261 * This checks if this month-of-year can be queried for the specified field. 262 * If false, then calling the {@link #range(TemporalField) range} and 263 * {@link #get(TemporalField) get} methods will throw an exception. 264 * <p> 265 * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then 266 * this method returns true. 267 * All other {@code ChronoField} instances will return false. 268 * <p> 269 * If the field is not a {@code ChronoField}, then the result of this method 270 * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)} 271 * passing {@code this} as the argument. 272 * Whether the field is supported is determined by the field. 273 * 274 * @param field the field to check, null returns false 275 * @return true if the field is supported on this month-of-year, false if not 276 */ 277 @Override 278 public boolean isSupported(TemporalField field) { 279 if (field instanceof ChronoField) { 280 return field == MONTH_OF_YEAR; 281 } 282 return field != null && field.isSupportedBy(this); 283 } 284 285 /** 286 * Gets the range of valid values for the specified field. 287 * <p> 288 * The range object expresses the minimum and maximum valid values for a field. 289 * This month is used to enhance the accuracy of the returned range. 290 * If it is not possible to return the range, because the field is not supported 291 * or for some other reason, an exception is thrown. 292 * <p> 293 * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the 294 * range of the month-of-year, from 1 to 12, will be returned. 295 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. 296 * <p> 297 * If the field is not a {@code ChronoField}, then the result of this method 298 * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)} 299 * passing {@code this} as the argument. 300 * Whether the range can be obtained is determined by the field. 301 * 302 * @param field the field to query the range for, not null 303 * @return the range of valid values for the field, not null 304 * @throws DateTimeException if the range for the field cannot be obtained 305 * @throws UnsupportedTemporalTypeException if the field is not supported 306 */ 307 @Override 308 public ValueRange range(TemporalField field) { 309 if (field == MONTH_OF_YEAR) { 310 return field.range(); 311 } 312 return TemporalAccessor.super.range(field); 313 } 314 315 /** 316 * Gets the value of the specified field from this month-of-year as an {@code int}. 317 * <p> 318 * This queries this month for the value of the specified field. 319 * The returned value will always be within the valid range of values for the field. 320 * If it is not possible to return the value, because the field is not supported 321 * or for some other reason, an exception is thrown. 322 * <p> 323 * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the 324 * value of the month-of-year, from 1 to 12, will be returned. 325 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. 326 * <p> 327 * If the field is not a {@code ChronoField}, then the result of this method 328 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} 329 * passing {@code this} as the argument. Whether the value can be obtained, 330 * and what the value represents, is determined by the field. 331 * 332 * @param field the field to get, not null 333 * @return the value for the field, within the valid range of values 334 * @throws DateTimeException if a value for the field cannot be obtained or 335 * the value is outside the range of valid values for the field 336 * @throws UnsupportedTemporalTypeException if the field is not supported or 337 * the range of values exceeds an {@code int} 338 * @throws ArithmeticException if numeric overflow occurs 339 */ 340 @Override 341 public int get(TemporalField field) { 342 if (field == MONTH_OF_YEAR) { 343 return getValue(); 344 } 345 return TemporalAccessor.super.get(field); 346 } 347 348 /** 349 * Gets the value of the specified field from this month-of-year as a {@code long}. 350 * <p> 351 * This queries this month for the value of the specified field. 352 * If it is not possible to return the value, because the field is not supported 353 * or for some other reason, an exception is thrown. 354 * <p> 355 * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the 356 * value of the month-of-year, from 1 to 12, will be returned. 357 * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. 358 * <p> 359 * If the field is not a {@code ChronoField}, then the result of this method 360 * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)} 361 * passing {@code this} as the argument. Whether the value can be obtained, 362 * and what the value represents, is determined by the field. 363 * 364 * @param field the field to get, not null 365 * @return the value for the field 366 * @throws DateTimeException if a value for the field cannot be obtained 367 * @throws UnsupportedTemporalTypeException if the field is not supported 368 * @throws ArithmeticException if numeric overflow occurs 369 */ 370 @Override 371 public long getLong(TemporalField field) { 372 if (field == MONTH_OF_YEAR) { 373 return getValue(); 374 } else if (field instanceof ChronoField) { 375 throw new UnsupportedTemporalTypeException("Unsupported field: " + field); 376 } 377 return field.getFrom(this); 378 } 379 380 //----------------------------------------------------------------------- 381 /** 382 * Returns the month-of-year that is the specified number of months after this one. 383 * <p> 384 * The calculation rolls around the end of the year from December to January. 385 * The specified period may be negative. 386 * <p> 387 * This instance is immutable and unaffected by this method call. 388 * 389 * @param months the months to add, positive or negative 390 * @return the resulting month, not null 391 */ 392 public Month plus(long months) { 393 int amount = (int) (months % 12); 394 return ENUMS[(ordinal() + (amount + 12)) % 12]; 395 } 396 397 /** 398 * Returns the month-of-year that is the specified number of months before this one. 399 * <p> 400 * The calculation rolls around the start of the year from January to December. 401 * The specified period may be negative. 402 * <p> 403 * This instance is immutable and unaffected by this method call. 404 * 405 * @param months the months to subtract, positive or negative 406 * @return the resulting month, not null 407 */ 408 public Month minus(long months) { 409 return plus(-(months % 12)); 410 } 411 412 //----------------------------------------------------------------------- 413 /** 414 * Gets the length of this month in days. 415 * <p> 416 * This takes a flag to determine whether to return the length for a leap year or not. 417 * <p> 418 * February has 28 days in a standard year and 29 days in a leap year. 419 * April, June, September and November have 30 days. 420 * All other months have 31 days. 421 * 422 * @param leapYear true if the length is required for a leap year 423 * @return the length of this month in days, from 28 to 31 424 */ 425 public int length(boolean leapYear) { 426 switch (this) { 427 case FEBRUARY: 428 return (leapYear ? 29 : 28); 429 case APRIL: 430 case JUNE: 431 case SEPTEMBER: 432 case NOVEMBER: 433 return 30; 434 default: 435 return 31; 436 } 437 } 438 439 /** 440 * Gets the minimum length of this month in days. 441 * <p> 442 * February has a minimum length of 28 days. 443 * April, June, September and November have 30 days. 444 * All other months have 31 days. 445 * 446 * @return the minimum length of this month in days, from 28 to 31 447 */ 448 public int minLength() { 449 switch (this) { 450 case FEBRUARY: 451 return 28; 452 case APRIL: 453 case JUNE: 454 case SEPTEMBER: 455 case NOVEMBER: 456 return 30; 457 default: 458 return 31; 459 } 460 } 461 462 /** 463 * Gets the maximum length of this month in days. 464 * <p> 465 * February has a maximum length of 29 days. 466 * April, June, September and November have 30 days. 467 * All other months have 31 days. 468 * 469 * @return the maximum length of this month in days, from 29 to 31 470 */ 471 public int maxLength() { 472 switch (this) { 473 case FEBRUARY: 474 return 29; 475 case APRIL: 476 case JUNE: 477 case SEPTEMBER: 478 case NOVEMBER: 479 return 30; 480 default: 481 return 31; 482 } 483 } 484 485 //----------------------------------------------------------------------- 486 /** 487 * Gets the day-of-year corresponding to the first day of this month. 488 * <p> 489 * This returns the day-of-year that this month begins on, using the leap 490 * year flag to determine the length of February. 491 * 492 * @param leapYear true if the length is required for a leap year 493 * @return the day of year corresponding to the first day of this month, from 1 to 336 494 */ 495 public int firstDayOfYear(boolean leapYear) { 496 int leap = leapYear ? 1 : 0; 497 switch (this) { 498 case JANUARY: 499 return 1; 500 case FEBRUARY: 501 return 32; 502 case MARCH: 503 return 60 + leap; 504 case APRIL: 505 return 91 + leap; 506 case MAY: 507 return 121 + leap; 508 case JUNE: 509 return 152 + leap; 510 case JULY: 511 return 182 + leap; 512 case AUGUST: 513 return 213 + leap; 514 case SEPTEMBER: 515 return 244 + leap; 516 case OCTOBER: 517 return 274 + leap; 518 case NOVEMBER: 519 return 305 + leap; 520 case DECEMBER: 521 default: 522 return 335 + leap; 523 } 524 } 525 526 /** 527 * Gets the month corresponding to the first month of this quarter. 528 * <p> 529 * The year can be divided into four quarters. 530 * This method returns the first month of the quarter for the base month. 531 * January, February and March return January. 532 * April, May and June return April. 533 * July, August and September return July. 534 * October, November and December return October. 535 * 536 * @return the first month of the quarter corresponding to this month, not null 537 */ 538 public Month firstMonthOfQuarter() { 539 return ENUMS[(ordinal() / 3) * 3]; 540 } 541 542 //----------------------------------------------------------------------- 543 /** 544 * Queries this month-of-year using the specified query. 545 * <p> 546 * This queries this month-of-year using the specified query strategy object. 547 * The {@code TemporalQuery} object defines the logic to be used to 548 * obtain the result. Read the documentation of the query to understand 549 * what the result of this method will be. 550 * <p> 551 * The result of this method is obtained by invoking the 552 * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the 553 * specified query passing {@code this} as the argument. 554 * 555 * @param <R> the type of the result 556 * @param query the query to invoke, not null 557 * @return the query result, null may be returned (defined by the query) 558 * @throws DateTimeException if unable to query (defined by the query) 559 * @throws ArithmeticException if numeric overflow occurs (defined by the query) 560 */ 561 @SuppressWarnings("unchecked") 562 @Override 563 public <R> R query(TemporalQuery<R> query) { 564 if (query == TemporalQueries.chronology()) { 565 return (R) IsoChronology.INSTANCE; 566 } else if (query == TemporalQueries.precision()) { 567 return (R) MONTHS; 568 } 569 return TemporalAccessor.super.query(query); 570 } 571 572 /** 573 * Adjusts the specified temporal object to have this month-of-year. 574 * <p> 575 * This returns a temporal object of the same observable type as the input 576 * with the month-of-year changed to be the same as this. 577 * <p> 578 * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)} 579 * passing {@link ChronoField#MONTH_OF_YEAR} as the field. 580 * If the specified temporal object does not use the ISO calendar system then 581 * a {@code DateTimeException} is thrown. 582 * <p> 583 * In most cases, it is clearer to reverse the calling pattern by using 584 * {@link Temporal#with(TemporalAdjuster)}: 585 * <pre> 586 * // these two lines are equivalent, but the second approach is recommended 587 * temporal = thisMonth.adjustInto(temporal); 588 * temporal = temporal.with(thisMonth); 589 * </pre> 590 * <p> 591 * For example, given a date in May, the following are output: 592 * <pre> 593 * dateInMay.with(JANUARY); // four months earlier 594 * dateInMay.with(APRIL); // one months earlier 595 * dateInMay.with(MAY); // same date 596 * dateInMay.with(JUNE); // one month later 597 * dateInMay.with(DECEMBER); // seven months later 598 * </pre> 599 * <p> 600 * This instance is immutable and unaffected by this method call. 601 * 602 * @param temporal the target object to be adjusted, not null 603 * @return the adjusted object, not null 604 * @throws DateTimeException if unable to make the adjustment 605 * @throws ArithmeticException if numeric overflow occurs 606 */ 607 @Override 608 public Temporal adjustInto(Temporal temporal) { 609 if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) { 610 throw new DateTimeException("Adjustment only supported on ISO date-time"); 611 } 612 return temporal.with(MONTH_OF_YEAR, getValue()); 613 } 614 615} 616