91  * This class defines the valid eras for the Japanese chronology.

    91  * The Japanese government defines the official name and start date of

    92  * Japan introduced the Gregorian calendar starting with Meiji 6.

    92  * each era. Eras are consecutive and their date ranges do not overlap,

    93  * Only Meiji and later eras are supported;

    93  * so the end date of one era is always the day before the start date

    94  * dates before Meiji 6, January 1 are not supported.

    94  * of the next era.

    95  * The number of the valid eras may increase, as new eras may be

    95  * <p>

    96  * defined by the Japanese government. Once an era is defined,

    96  * The Java SE Platform supports all eras defined by the Japanese government,

    97  * future versions of the platform may add a singleton instance

    97  * beginning with the Meiji era. Each era is identified in the Platform by an

    98  * for it. The defined era is expected to have a consecutive integer

    98  * integer value and a name. The {@link #of(int)} and {@link #valueOf(String)}

    99  * associated with it.

    99  * methods may be used to obtain a singleton instance of {@code JapaneseEra}

   100  * for each era. The {@link #values()} method returns the singleton instances

   101  * of all 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 {@link #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.

   202      * <p>

   220      * <ul>

   203      * The {@link #SHOWA} era that contains 1970-01-01 (ISO calendar system) has the value 1.

   221      * <li>The value {@code 1} is associated with the 'Showa' era, because

   204      * Later era is numbered 2 ({@link #HEISEI}). Earlier eras are numbered 0 ({@link #TAISHO}),

   222      * it contains 1970-01-01 (ISO calendar system).</li>

   205      * -1 ({@link #MEIJI}), only Meiji and later eras are supported.

   223      * <li>The values {@code -1} and {@code 0} are associated with two earlier

   206      * <p>

   224      * eras, Meiji and Taisho, respectively.</li>

   207      * In addition to the known era singletons, values for additional

   225      * <li>A value greater than {@code 1} is associated with a later era,

   208      * eras may be defined. Those values are the {@link Era#getValue()}

   226      * beginning with Heisei ({@code 2}).</li>

   209      * of corresponding eras from the {@link #values()} method.

   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.