1 /*
   2  * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
   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
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  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).
  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) 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  */
  62 package java.time.chrono;
  63 
  64 
  65 import java.time.DateTimeException;
  66 import java.time.LocalDate;
  67 
  68 /**
  69  * An era in the ISO calendar system.
  70  * <p>
  71  * The ISO-8601 standard does not define eras.
  72  * A definition has therefore been created with two eras - 'Current era' (CE) for
  73  * years from 0001-01-01 (ISO) and 'Before current era' (BCE) for years before that.
  74  * <p>
  75  * <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code IsoEra}.
  76  * Use {@code getValue()} instead.</b>
  77  *
  78  * <h3>Specification for implementors</h3>
  79  * This is an immutable and thread-safe enum.
  80  *
  81  * @since 1.8
  82  */
  83 enum IsoEra implements Era {
  84 
  85     /**
  86      * The singleton instance for the era BCE, 'Before Current Era'.
  87      * The 'ISO' part of the name emphasizes that this differs from the BCE
  88      * era in the Gregorian calendar system.
  89      * This has the numeric value of {@code 0}.
  90      */
  91     BCE,
  92     /**
  93      * The singleton instance for the era CE, 'Current Era'.
  94      * The 'ISO' part of the name emphasizes that this differs from the CE
  95      * era in the Gregorian calendar system.
  96      * This has the numeric value of {@code 1}.
  97      */
  98     CE;
  99 
 100     //-----------------------------------------------------------------------
 101     /**
 102      * Obtains an instance of {@code IsoEra} from an {@code int} value.
 103      * <p>
 104      * {@code IsoEra} is an enum representing the ISO eras of BCE/CE.
 105      * This factory allows the enum to be obtained from the {@code int} value.
 106      *
 107      * @param era  the BCE/CE value to represent, from 0 (BCE) to 1 (CE)
 108      * @return the era singleton, not null
 109      * @throws DateTimeException if the value is invalid
 110      */
 111     public static IsoEra of(int era) {
 112         switch (era) {
 113             case 0:
 114                 return BCE;
 115             case 1:
 116                 return CE;
 117             default:
 118                 throw new DateTimeException("Invalid era: " + era);
 119         }
 120     }
 121 
 122     //-----------------------------------------------------------------------
 123     /**
 124      * Gets the numeric era {@code int} value.
 125      * <p>
 126      * The era BCE has the value 0, while the era CE has the value 1.
 127      *
 128      * @return the era value, from 0 (BCE) to 1 (CE)
 129      */
 130     @Override
 131     public int getValue() {
 132         return ordinal();
 133     }
 134 
 135     @Override
 136     public IsoChronology getChronology() {
 137         return IsoChronology.INSTANCE;
 138     }
 139 
 140     // JDK8 default methods:
 141     //-----------------------------------------------------------------------
 142     @Override
 143     public LocalDate date(int year, int month, int day) {
 144         return getChronology().date(this, year, month, day);
 145     }
 146 
 147     @Override
 148     public LocalDate dateYearDay(int year, int dayOfYear) {
 149         return getChronology().dateYearDay(this, year, dayOfYear);
 150     }
 151 
 152 }