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/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
*
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package java.time.chrono;
import java.time.DateTimeException;
/**
* An era in the ISO calendar system.
* <p>
* The ISO-8601 standard does not define eras.
* A definition has therefore been created with two eras - 'Current era' (CE) for
* years on or after 0001-01-01 (ISO), and 'Before current era' (BCE) for years before that.
*
* <table summary="ISO years and eras" cellpadding="2" cellspacing="3" border="0" >
* <thead>
* <tr class="tableSubHeadingColor">
* <th class="colFirst" align="left">year-of-era</th>
* <th class="colFirst" align="left">era</th>
* <th class="colLast" align="left">proleptic-year</th>
* </tr>
* </thead>
* <tbody>
* <tr class="rowColor">
* <td>2</td><td>CE</td><td>2</td>
* </tr>
* <tr class="altColor">
* <td>1</td><td>CE</td><td>1</td>
* </tr>
* <tr class="rowColor">
* <td>1</td><td>BCE</td><td>0</td>
* </tr>
* <tr class="altColor">
* <td>2</td><td>BCE</td><td>-1</td>
* </tr>
* </tbody>
* </table>
* <p>
* <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code IsoEra}.
* Use {@code getValue()} instead.</b>
*
* @implSpec
* This is an immutable and thread-safe enum.
*
* @since 1.8
*/
public enum IsoEra implements Era {
/**
* The singleton instance for the era before the current one, 'Before Current Era',
* which has the numeric value 0.
*/
BCE,
/**
* The singleton instance for the current era, 'Current Era',
* which has the numeric value 1.
*/
CE;
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code IsoEra} from an {@code int} value.
* <p>
* {@code IsoEra} is an enum representing the ISO eras of BCE/CE.
* This factory allows the enum to be obtained from the {@code int} value.
*
* @param isoEra the BCE/CE value to represent, from 0 (BCE) to 1 (CE)
* @return the era singleton, not null
* @throws DateTimeException if the value is invalid
*/
public static IsoEra of(int isoEra) {
switch (isoEra) {
case 0:
return BCE;
case 1:
return CE;
default:
throw new DateTimeException("Invalid era: " + isoEra);
}
}
//-----------------------------------------------------------------------
/**
* Gets the numeric era {@code int} value.
* <p>
* The era BCE has the value 0, while the era CE has the value 1.
*
* @return the era value, from 0 (BCE) to 1 (CE)
*/
@Override
public int getValue() {
return ordinal();
}
}