1 /*
 2  * Copyright (c) 2022, 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
23  * questions.
24  */
25 package java.lang;
26 
27 import jdk.internal.javac.PreviewFeature;
28 
29 /**
30  * Thrown when an identity object is required but a value object is supplied.
31  * <p>
32  * Identity objects are required for synchronization and locking.
33  * <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">Value-based</a>
34  * objects do not have identity and cannot be used for synchronization, locking,
35  * or any type of {@link java.lang.ref.Reference}.
36  *
37  * @since 28
38  */
39 @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
40 public final class IdentityException extends RuntimeException {
41     @java.io.Serial
42     private static final long serialVersionUID = 1L;
43 
44     /**
45      * Create an {@code IdentityException} with no message.
46      */
47     public IdentityException() {
48     }
49 
50     /**
51      * Create an {@code IdentityException} with a message.
52      *
53      * @param  message the detail message; can be {@code null}
54      */
55     public IdentityException(String message) {
56         super(message);
57     }
58 }