1 /*
2 * Copyright (c) 2012, 2017, 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 import java.time.DateTimeException;
65
66 /**
67 * An era in the ISO calendar system.
68 * <p>
69 * The ISO-8601 standard does not define eras.
70 * A definition has therefore been created with two eras - 'Current era' (CE) for
71 * years on or after 0001-01-01 (ISO), and 'Before current era' (BCE) for years before that.
72 *
73 * <table class="striped" style="text-align:left">
74 * <caption style="display:none">ISO years and eras</caption>
75 * <thead>
76 * <tr>
77 * <th scope="col">year-of-era</th>
78 * <th scope="col">era</th>
79 * <th scope="col">proleptic-year</th>
80 * </tr>
81 * </thead>
82 * <tbody>
83 * <tr>
84 * <td>2</td><td>CE</td><th scope="row">2</th>
85 * </tr>
86 * <tr>
87 * <td>1</td><td>CE</td><th scope="row">1</th>
88 * </tr>
89 * <tr>
90 * <td>1</td><td>BCE</td><th scope="row">0</th>
91 * </tr>
92 * <tr>
93 * <td>2</td><td>BCE</td><th scope="row">-1</th>
94 * </tr>
95 * </tbody>
96 * </table>
97 * <p>
98 * <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code IsoEra}.
99 * Use {@code getValue()} instead.</b>
100 *
101 * @implSpec
102 * This is an immutable and thread-safe enum.
103 *
104 * @since 1.8
105 */
106 public enum IsoEra implements Era {
107
108 /**
109 * The singleton instance for the era before the current one, 'Before Current Era',
110 * which has the numeric value 0.
111 */
112 BCE,
113 /**
114 * The singleton instance for the current era, 'Current Era',
115 * which has the numeric value 1.
116 */
117 CE;
118
119 //-----------------------------------------------------------------------
120 /**
121 * Obtains an instance of {@code IsoEra} from an {@code int} value.
122 * <p>
123 * {@code IsoEra} is an enum representing the ISO eras of BCE/CE.
124 * This factory allows the enum to be obtained from the {@code int} value.
125 *
126 * @param isoEra the BCE/CE value to represent, from 0 (BCE) to 1 (CE)
127 * @return the era singleton, not null
128 * @throws DateTimeException if the value is invalid
129 */
130 public static IsoEra of(int isoEra) {
131 switch (isoEra) {
132 case 0:
133 return BCE;
134 case 1:
135 return CE;
136 default:
137 throw new DateTimeException("Invalid era: " + isoEra);
138 }
139 }
140
141 //-----------------------------------------------------------------------
142 /**
143 * Gets the numeric era {@code int} value.
144 * <p>
145 * The era BCE has the value 0, while the era CE has the value 1.
146 *
147 * @return the era value, from 0 (BCE) to 1 (CE)
148 */
149 @Override
150 public int getValue() {
151 return ordinal();
152 }
153
154 }