1 /*
2 * Copyright (c) 2012, 2025, 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
104 import jdk.internal.util.DecimalDigits;
105
106 /**
107 * A year-month in the ISO-8601 calendar system, such as {@code 2007-12}.
108 * <p>
109 * {@code YearMonth} is an immutable date-time object that represents the combination
110 * of a year and month. Any field that can be derived from a year and month, such as
111 * quarter-of-year, can be obtained.
112 * <p>
113 * This class does not store or represent a day, time or time-zone.
114 * For example, the value "October 2007" can be stored in a {@code YearMonth}.
115 * <p>
116 * The ISO-8601 calendar system is the modern civil calendar system used today
117 * in most of the world. It is equivalent to the proleptic Gregorian calendar
118 * system, in which today's rules for leap years are applied for all time.
119 * For most applications written today, the ISO-8601 rules are entirely suitable.
120 * However, any application that makes use of historical dates, and requires them
121 * to be accurate will find the ISO-8601 approach unsuitable.
122 * <p>
123 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
124 * class; programmers should treat instances that are
125 * {@linkplain #equals(Object) equal} as interchangeable and should not
126 * use instances for synchronization, or unpredictable behavior may
127 * occur. For example, in a future release, synchronization may fail.
128 * The {@code equals} method should be used for comparisons.
129 *
130 * @implSpec
131 * This class is immutable and thread-safe.
132 *
133 * @since 1.8
134 */
135 @jdk.internal.ValueBased
136 public final class YearMonth
137 implements Temporal, TemporalAdjuster, Comparable<YearMonth>, Serializable {
138
139 /**
140 * Serialization version.
141 */
142 @java.io.Serial
143 private static final long serialVersionUID = 4183400860270640070L;
144
145 /**
146 * For backward compatibility of the serialized {@code YearMonth.class} object,
147 * explicitly declare the types of the serialized fields as defined in Java SE 8.
148 * Instances of {@code YearMonth} are serialized using the dedicated
149 * serialized form by {@code writeReplace}.
150 * @serialField year int The year.
151 * @serialField month int The month-of-year.
152 */
153 @java.io.Serial
154 private static final ObjectStreamField[] serialPersistentFields = {
155 new ObjectStreamField("year", int.class),
156 new ObjectStreamField("month", int.class),
1236 * <pre>
1237 * out.writeByte(12); // identifies a YearMonth
1238 * out.writeInt(year);
1239 * out.writeByte(month);
1240 * </pre>
1241 *
1242 * @return the instance of {@code Ser}, not null
1243 */
1244 @java.io.Serial
1245 private Object writeReplace() {
1246 return new Ser(Ser.YEAR_MONTH_TYPE, this);
1247 }
1248
1249 /**
1250 * Defend against malicious streams.
1251 *
1252 * @param s the stream to read
1253 * @throws InvalidObjectException always
1254 */
1255 @java.io.Serial
1256 private void readObject(ObjectInputStream s) throws InvalidObjectException {
1257 throw new InvalidObjectException("Deserialization via serialization delegate");
1258 }
1259
1260 void writeExternal(DataOutput out) throws IOException {
1261 out.writeInt(year);
1262 out.writeByte(month);
1263 }
1264
1265 static YearMonth readExternal(DataInput in) throws IOException {
1266 int year = in.readInt();
1267 byte month = in.readByte();
1268 return YearMonth.of(year, month);
1269 }
1270
1271 }
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1 /*
2 * Copyright (c) 2012, 2026, 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
104 import jdk.internal.util.DecimalDigits;
105
106 /**
107 * A year-month in the ISO-8601 calendar system, such as {@code 2007-12}.
108 * <p>
109 * {@code YearMonth} is an immutable date-time object that represents the combination
110 * of a year and month. Any field that can be derived from a year and month, such as
111 * quarter-of-year, can be obtained.
112 * <p>
113 * This class does not store or represent a day, time or time-zone.
114 * For example, the value "October 2007" can be stored in a {@code YearMonth}.
115 * <p>
116 * The ISO-8601 calendar system is the modern civil calendar system used today
117 * in most of the world. It is equivalent to the proleptic Gregorian calendar
118 * system, in which today's rules for leap years are applied for all time.
119 * For most applications written today, the ISO-8601 rules are entirely suitable.
120 * However, any application that makes use of historical dates, and requires them
121 * to be accurate will find the ISO-8601 approach unsuitable.
122 * <p>
123 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
124 * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
125 * as interchangeable and should not use instances for synchronization or
126 * with {@linkplain java.lang.ref.Reference object references}.
127 *
128 * <div class="preview-block">
129 * <div class="preview-comment">
130 * When preview features are enabled, {@code YearMonth} is a {@linkplain Class#isValue value class}.
131 * Use of value class instances for synchronization or with
132 * {@linkplain java.lang.ref.Reference object references} result in
133 * {@link IdentityException}.
134 * </div>
135 * </div>
136 *
137 * @implSpec
138 * This class is immutable and thread-safe.
139 *
140 * @since 1.8
141 */
142 @jdk.internal.ValueBased
143 public final /*value*/ class YearMonth
144 implements Temporal, TemporalAdjuster, Comparable<YearMonth>, Serializable {
145
146 /**
147 * Serialization version.
148 */
149 @java.io.Serial
150 private static final long serialVersionUID = 4183400860270640070L;
151
152 /**
153 * For backward compatibility of the serialized {@code YearMonth.class} object,
154 * explicitly declare the types of the serialized fields as defined in Java SE 8.
155 * Instances of {@code YearMonth} are serialized using the dedicated
156 * serialized form by {@code writeReplace}.
157 * @serialField year int The year.
158 * @serialField month int The month-of-year.
159 */
160 @java.io.Serial
161 private static final ObjectStreamField[] serialPersistentFields = {
162 new ObjectStreamField("year", int.class),
163 new ObjectStreamField("month", int.class),
1243 * <pre>
1244 * out.writeByte(12); // identifies a YearMonth
1245 * out.writeInt(year);
1246 * out.writeByte(month);
1247 * </pre>
1248 *
1249 * @return the instance of {@code Ser}, not null
1250 */
1251 @java.io.Serial
1252 private Object writeReplace() {
1253 return new Ser(Ser.YEAR_MONTH_TYPE, this);
1254 }
1255
1256 /**
1257 * Defend against malicious streams.
1258 *
1259 * @param s the stream to read
1260 * @throws InvalidObjectException always
1261 */
1262 @java.io.Serial
1263 @SuppressWarnings("serial") // this method is not invoked for value classes
1264 private void readObject(ObjectInputStream s) throws InvalidObjectException {
1265 throw new InvalidObjectException("Deserialization via serialization delegate");
1266 }
1267
1268 void writeExternal(DataOutput out) throws IOException {
1269 out.writeInt(year);
1270 out.writeByte(month);
1271 }
1272
1273 static YearMonth readExternal(DataInput in) throws IOException {
1274 int year = in.readInt();
1275 byte month = in.readByte();
1276 return YearMonth.of(year, month);
1277 }
1278
1279 }
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