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   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
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   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
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  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).
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  17  * You should have received a copy of the GNU General Public License version
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  25 
  26 /*
  27  * This file is available under and governed by the GNU General Public
  28  * License version 2 only, as published by the Free Software Foundation.
  29  * However, the following notice accompanied the original version of this
  30  * file:
  31  *
  32  * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
  33  *
  34  * All rights reserved.
  35  *
  36  * Redistribution and use in source and binary forms, with or without
  37  * modification, are permitted provided that the following conditions are met:
  38  *
  39  *  * Redistributions of source code must retain the above copyright notice,
  40  *    this list of conditions and the following disclaimer.
  41  *
  42  *  * Redistributions in binary form must reproduce the above copyright notice,
  43  *    this list of conditions and the following disclaimer in the documentation
  44  *    and/or other materials provided with the distribution.
  45  *
  46  *  * Neither the name of JSR-310 nor the names of its contributors
  47  *    may be used to endorse or promote products derived from this software
  48  *    without specific prior written permission.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  51  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  52  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  53  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  54  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  55  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  56  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  57  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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  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.chrono;
  63 
  64 import static java.time.chrono.JapaneseDate.MEIJI_6_ISODATE;
  65 import static java.time.temporal.ChronoField.ERA;
  66 
  67 import java.io.DataInput;
  68 import java.io.DataOutput;
  69 import java.io.IOException;
  70 import java.io.InvalidObjectException;
  71 import java.io.ObjectInputStream;
  72 import java.io.ObjectStreamException;
  73 import java.io.Serializable;
  74 import java.time.DateTimeException;
  75 import java.time.LocalDate;
  76 import java.time.format.DateTimeFormatterBuilder;
  77 import java.time.format.TextStyle;
  78 import java.time.temporal.ChronoField;
  79 import java.time.temporal.TemporalField;
  80 import java.time.temporal.UnsupportedTemporalTypeException;
  81 import java.time.temporal.ValueRange;
  82 import java.util.Arrays;
  83 import java.util.Locale;
  84 import java.util.Objects;
  85 
  86 import sun.util.calendar.CalendarDate;
  87 
  88 /**
  89  * An era in the Japanese Imperial calendar system.
  90  * <p>
  91  * The Japanese government defines the official name and start date of
  92  * each era. Eras are consecutive and their date ranges do not overlap,
  93  * so the end date of one era is always the day before the start date
  94  * of the next era.
  95  * <p>
  96  * The Java SE Platform supports all eras defined by the Japanese government,
  97  * beginning with the Meiji era. Each era is identified in the Platform by an
  98  * integer value and a name. The {@link #of(int)} and {@link #valueOf(String)}
  99  * methods may be used to obtain a singleton instance of JapaneseEra for each
 100  * era. The {@link #values()} method returns the singleton instances of all
 101  * supported eras.
 102  * <p>
 103  * For convenience, this class declares a number of public static final fields
 104  * that refer to singleton instances returned by the values() method.
 105  *
 106  * @apiNote
 107  * The fields declared in this class may evolve over time, in line with the
 108  * results of the {@link #values()} method. However, there is not necessarily
 109  * a 1:1 correspondence between the fields and the singleton instances.
 110  *
 111  * @apiNote
 112  * The Japanese government may announce a new era and define its start
 113  * date but not its official name. In this scenario, the singleton instance
 114  * that represents the new era may return a name that is not stable until
 115  * the official name is defined. Developers should exercise caution when
 116  * relying on the name returned by any singleton instance that does not
 117  * correspond to a public static final field.
 118  *
 119  * @implSpec
 120  * This class is immutable and thread-safe.
 121  *
 122  * @since 1.8
 123  */
 124 public final class JapaneseEra
 125         implements Era, Serializable {
 126 
 127     // The offset value to 0-based index from the era value.
 128     // i.e., getValue() + ERA_OFFSET == 0-based index
 129     static final int ERA_OFFSET = 2;
 130 
 131     static final sun.util.calendar.Era[] ERA_CONFIG;
 132 
 133     /**
 134      * The singleton instance for the 'Meiji' era (1868-01-01 - 1912-07-29)
 135      * which has the value -1.
 136      */
 137     public static final JapaneseEra MEIJI = new JapaneseEra(-1, LocalDate.of(1868, 1, 1));
 138     /**
 139      * The singleton instance for the 'Taisho' era (1912-07-30 - 1926-12-24)
 140      * which has the value 0.
 141      */
 142     public static final JapaneseEra TAISHO = new JapaneseEra(0, LocalDate.of(1912, 7, 30));
 143     /**
 144      * The singleton instance for the 'Showa' era (1926-12-25 - 1989-01-07)
 145      * which has the value 1.
 146      */
 147     public static final JapaneseEra SHOWA = new JapaneseEra(1, LocalDate.of(1926, 12, 25));
 148     /**
 149      * The singleton instance for the 'Heisei' era (1989-01-08 - 2019-04-30)
 150      * which has the value 2.
 151      */
 152     public static final JapaneseEra HEISEI = new JapaneseEra(2, LocalDate.of(1989, 1, 8));
 153     /**
 154      * The singleton instance for the 'NewEra' era (2019-05-01 - current)
 155      * which has the value 3.
 156      */
 157     private static final JapaneseEra NEWERA = new JapaneseEra(3, LocalDate.of(2019, 5, 1));
 158 
 159     // The number of predefined JapaneseEra constants.
 160     // There may be a supplemental era defined by the property.
 161     private static final int N_ERA_CONSTANTS = NEWERA.getValue() + ERA_OFFSET;
 162 
 163     /**
 164      * Serialization version.
 165      */
 166     private static final long serialVersionUID = 1466499369062886794L;
 167 
 168     // array for the singleton JapaneseEra instances
 169     private static final JapaneseEra[] KNOWN_ERAS;
 170 
 171     static {
 172         ERA_CONFIG = JapaneseChronology.JCAL.getEras();
 173 
 174         KNOWN_ERAS = new JapaneseEra[ERA_CONFIG.length];
 175         KNOWN_ERAS[0] = MEIJI;
 176         KNOWN_ERAS[1] = TAISHO;
 177         KNOWN_ERAS[2] = SHOWA;
 178         KNOWN_ERAS[3] = HEISEI;
 179         KNOWN_ERAS[4] = NEWERA;
 180         for (int i = N_ERA_CONSTANTS; i < ERA_CONFIG.length; i++) {
 181             CalendarDate date = ERA_CONFIG[i].getSinceDate();
 182             LocalDate isoDate = LocalDate.of(date.getYear(), date.getMonth(), date.getDayOfMonth());
 183             KNOWN_ERAS[i] = new JapaneseEra(i - ERA_OFFSET + 1, isoDate);
 184         }
 185     };
 186 
 187     /**
 188      * The era value.
 189      * @serial
 190      */
 191     private final transient int eraValue;
 192 
 193     // the first day of the era
 194     private final transient LocalDate since;
 195 
 196     /**
 197      * Creates an instance.
 198      *
 199      * @param eraValue  the era value, validated
 200      * @param since  the date representing the first date of the era, validated not null
 201      */
 202     private JapaneseEra(int eraValue, LocalDate since) {
 203         this.eraValue = eraValue;
 204         this.since = since;
 205     }
 206 
 207     //-----------------------------------------------------------------------
 208     /**
 209      * Returns the Sun private Era instance corresponding to this {@code JapaneseEra}.
 210      *
 211      * @return the Sun private Era instance for this {@code JapaneseEra}.
 212      */
 213     sun.util.calendar.Era getPrivateEra() {
 214         return ERA_CONFIG[ordinal(eraValue)];
 215     }
 216 
 217     //-----------------------------------------------------------------------
 218     /**
 219      * Obtains an instance of {@code JapaneseEra} from an {@code int} value.
 220       * <ul>
 221       * <li>The value {@code 1} is associated with the 'Showa' era, because
 222       * it contains 1970-01-01 (ISO calendar system).</li>
 223       * <li>The values {@code -1} and {@code 0} are associated with two earlier
 224       * eras, Meiji and Taisho, respectively.</li>
 225       * <li>A value greater than {@code 1} is associated with a later era,
 226       * beginning with Heisei ({@code 2}).</li>
 227       * </ul>
 228      * <p>
 229       * Every instance of {@code JapaneseEra} that is returned from the {@link values()}
 230       * method has an int value (available via {@link Era#getValue()} which is
 231       * accepted by this method.
 232      *
 233      * @param japaneseEra  the era to represent
 234      * @return the {@code JapaneseEra} singleton, not null
 235      * @throws DateTimeException if the value is invalid
 236      */
 237     public static JapaneseEra of(int japaneseEra) {
 238         if (japaneseEra < MEIJI.eraValue || japaneseEra + ERA_OFFSET > KNOWN_ERAS.length) {
 239             throw new DateTimeException("Invalid era: " + japaneseEra);
 240         }
 241         return KNOWN_ERAS[ordinal(japaneseEra)];
 242     }
 243 
 244     /**
 245      * Returns the {@code JapaneseEra} with the name.
 246      * <p>
 247      * The string must match exactly the name of the era.
 248      * (Extraneous whitespace characters are not permitted.)
 249      *
 250      * @param japaneseEra  the japaneseEra name; non-null
 251      * @return the {@code JapaneseEra} singleton, never null
 252      * @throws IllegalArgumentException if there is not JapaneseEra with the specified name
 253      */
 254     public static JapaneseEra valueOf(String japaneseEra) {
 255         Objects.requireNonNull(japaneseEra, "japaneseEra");
 256         for (JapaneseEra era : KNOWN_ERAS) {
 257             if (era.getName().equals(japaneseEra)) {
 258                 return era;
 259             }
 260         }
 261         throw new IllegalArgumentException("japaneseEra is invalid");
 262     }
 263 
 264     /**
 265      * Returns an array of JapaneseEras.
 266      * <p>
 267      * This method may be used to iterate over the JapaneseEras as follows:
 268      * <pre>
 269      * for (JapaneseEra c : JapaneseEra.values())
 270      *     System.out.println(c);
 271      * </pre>
 272      *
 273      * @return an array of JapaneseEras
 274      */
 275     public static JapaneseEra[] values() {
 276         return Arrays.copyOf(KNOWN_ERAS, KNOWN_ERAS.length);
 277     }
 278 
 279     /**
 280      * {@inheritDoc}
 281      *
 282      * @param style {@inheritDoc}
 283      * @param locale {@inheritDoc}
 284      */
 285     @Override
 286     public String getDisplayName(TextStyle style, Locale locale) {
 287         // If this JapaneseEra is a supplemental one, obtain the name from
 288         // the era definition.
 289         if (getValue() > N_ERA_CONSTANTS - ERA_OFFSET) {
 290             Objects.requireNonNull(locale, "locale");
 291             return style.asNormal() == TextStyle.NARROW ? getAbbreviation() : getName();
 292         }
 293 
 294         return new DateTimeFormatterBuilder()
 295             .appendText(ERA, style)
 296             .toFormatter(locale)
 297             .withChronology(JapaneseChronology.INSTANCE)
 298             .format(this == MEIJI ? MEIJI_6_ISODATE : since);
 299     }
 300 
 301     //-----------------------------------------------------------------------
 302     /**
 303      * Obtains an instance of {@code JapaneseEra} from a date.
 304      *
 305      * @param date  the date, not null
 306      * @return the Era singleton, never null
 307      */
 308     static JapaneseEra from(LocalDate date) {
 309         if (date.isBefore(MEIJI_6_ISODATE)) {
 310             throw new DateTimeException("JapaneseDate before Meiji 6 are not supported");
 311         }
 312         for (int i = KNOWN_ERAS.length - 1; i > 0; i--) {
 313             JapaneseEra era = KNOWN_ERAS[i];
 314             if (date.compareTo(era.since) >= 0) {
 315                 return era;
 316             }
 317         }
 318         return null;
 319     }
 320 
 321     static JapaneseEra toJapaneseEra(sun.util.calendar.Era privateEra) {
 322         for (int i = ERA_CONFIG.length - 1; i >= 0; i--) {
 323             if (ERA_CONFIG[i].equals(privateEra)) {
 324                 return KNOWN_ERAS[i];
 325             }
 326         }
 327         return null;
 328     }
 329 
 330     static sun.util.calendar.Era privateEraFrom(LocalDate isoDate) {
 331         for (int i = KNOWN_ERAS.length - 1; i > 0; i--) {
 332             JapaneseEra era = KNOWN_ERAS[i];
 333             if (isoDate.compareTo(era.since) >= 0) {
 334                 return ERA_CONFIG[i];
 335             }
 336         }
 337         return null;
 338     }
 339 
 340     /**
 341      * Returns the index into the arrays from the Era value.
 342      * the eraValue is a valid Era number, -1..2.
 343      *
 344      * @param eraValue  the era value to convert to the index
 345      * @return the index of the current Era
 346      */
 347     private static int ordinal(int eraValue) {
 348         return eraValue + ERA_OFFSET - 1;
 349     }
 350 
 351     //-----------------------------------------------------------------------
 352     /**
 353      * Gets the numeric era {@code int} value.
 354      * <p>
 355      * The {@link #SHOWA} era that contains 1970-01-01 (ISO calendar system) has the value 1.
 356      * Later eras are numbered from 2 ({@link #HEISEI}).
 357      * Earlier eras are numbered 0 ({@link #TAISHO}), -1 ({@link #MEIJI})).
 358      *
 359      * @return the era value
 360      */
 361     @Override
 362     public int getValue() {
 363         return eraValue;
 364     }
 365 
 366     //-----------------------------------------------------------------------
 367     /**
 368      * Gets the range of valid values for the specified field.
 369      * <p>
 370      * The range object expresses the minimum and maximum valid values for a field.
 371      * This era is used to enhance the accuracy of the returned range.
 372      * If it is not possible to return the range, because the field is not supported
 373      * or for some other reason, an exception is thrown.
 374      * <p>
 375      * If the field is a {@link ChronoField} then the query is implemented here.
 376      * The {@code ERA} field returns the range.
 377      * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
 378      * <p>
 379      * If the field is not a {@code ChronoField}, then the result of this method
 380      * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
 381      * passing {@code this} as the argument.
 382      * Whether the range can be obtained is determined by the field.
 383      * <p>
 384      * The range of valid Japanese eras can change over time due to the nature
 385      * of the Japanese calendar system.
 386      *
 387      * @param field  the field to query the range for, not null
 388      * @return the range of valid values for the field, not null
 389      * @throws DateTimeException if the range for the field cannot be obtained
 390      * @throws UnsupportedTemporalTypeException if the unit is not supported
 391      */
 392     @Override  // override as super would return range from 0 to 1
 393     public ValueRange range(TemporalField field) {
 394         if (field == ERA) {
 395             return JapaneseChronology.INSTANCE.range(ERA);
 396         }
 397         return Era.super.range(field);
 398     }
 399 
 400     //-----------------------------------------------------------------------
 401     String getAbbreviation() {
 402         return ERA_CONFIG[ordinal(getValue())].getAbbreviation();
 403     }
 404 
 405     String getName() {
 406         return ERA_CONFIG[ordinal(getValue())].getName();
 407     }
 408 
 409     @Override
 410     public String toString() {
 411         return getName();
 412     }
 413 
 414     //-----------------------------------------------------------------------
 415     /**
 416      * Defend against malicious streams.
 417      *
 418      * @param s the stream to read
 419      * @throws InvalidObjectException always
 420      */
 421     private void readObject(ObjectInputStream s) throws InvalidObjectException {
 422         throw new InvalidObjectException("Deserialization via serialization delegate");
 423     }
 424 
 425     //-----------------------------------------------------------------------
 426     /**
 427      * Writes the object using a
 428      * <a href="../../../serialized-form.html#java.time.chrono.Ser">dedicated serialized form</a>.
 429      * @serialData
 430      * <pre>
 431      *  out.writeByte(5);        // identifies a JapaneseEra
 432      *  out.writeInt(getValue());
 433      * </pre>
 434      *
 435      * @return the instance of {@code Ser}, not null
 436      */
 437     private Object writeReplace() {
 438         return new Ser(Ser.JAPANESE_ERA_TYPE, this);
 439     }
 440 
 441     void writeExternal(DataOutput out) throws IOException {
 442         out.writeByte(this.getValue());
 443     }
 444 
 445     static JapaneseEra readExternal(DataInput in) throws IOException {
 446         byte eraValue = in.readByte();
 447         return JapaneseEra.of(eraValue);
 448     }
 449 
 450 }