InternationalFixedEra.java

/*
 * Copyright (c) 2007-present, Stephen Colebourne & Michael Nascimento Santos
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package org.threeten.extra.chrono;

import java.time.DateTimeException;
import java.time.chrono.Era;

/**
 * An era in the International Fixed calendar system.
 * <p>
 * The International Fixed calendar system officially only has one era.
 * The current era, for years from 1 onwards, is known as 'Current Era'.
 * All previous years are invalid.
 * <p>
 * The start of the International Fixed epoch {@code 0001/01/01 (IFC)} is {@code 0001-01-01 (ISO)}.
 * <p>
 * <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code InternationalFixedEra}.
 * Use {@code getValue()} instead.</b>
 *
 * <h3>Implementation Requirements:</h3>
 * This is an immutable and thread-safe enum.
 */
public enum InternationalFixedEra implements Era {

    /**
     * The singleton instance for the current era, 'Current Era',
     * which has the numeric value 1.
     */
    CE;

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code InternationalFixedEra} from an {@code int} value.
     * <p>
     * {@code InternationalFixedEra} is an enum representing the International Fixed era of CE.
     * This factory allows the enum to be obtained from the {@code int} value.
     *
     * @param era  the CE value to represent, only 1 (CE)
     * @return the era singleton, not null
     * @throws DateTimeException if the value is invalid
     */
    public static InternationalFixedEra of(final int era) {
        if (era == 1) {
            return CE;
        }
        throw new DateTimeException("Invalid era: " + era);
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the numeric era {@code int} value.
     * <p>
     * The era CE has the value 1.
     *
     * @return the era value, only 1 (CE)
     */
    @Override
    public int getValue() {
        return 1;
    }

}