diff --git a/src/java.base/share/classes/java/lang/IdentityException.java b/src/java.base/share/classes/java/lang/IdentityException.java new file mode 100644 index 00000000000..749ec5f5de9 --- /dev/null +++ b/src/java.base/share/classes/java/lang/IdentityException.java @@ -0,0 +1,83 @@ +/* + * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ +package java.lang; + + +/** + * Thrown when an identity object is required but a value object is supplied. + *
+ * Identity objects are required for synchronization and locking. + * Value-based + * objects do not have identity and cannot be used for synchronization or locking. + * + * @since Valhalla + */ +public class IdentityException extends RuntimeException { + @java.io.Serial + private static final long serialVersionUID = 1L; + + /** + * Create an {@code IdentityException} with no message. + */ + public IdentityException() { + } + + /** + * Create an {@code IdentityException} with the class name and default message. + * + * @param clazz the class of the object + */ + public IdentityException(Class> clazz) { + super(clazz.getName() + " is not an identity class"); + } + + /** + * Create an {@code IdentityException} with a message. + * + * @param message the detail message; can be {@code null} + */ + public IdentityException(String message) { + super(message); + } + + /** + * Create an {@code IdentityException} with a cause. + * + * @param cause the cause; {@code null} is permitted, and indicates + * that the cause is nonexistent or unknown. + */ + public IdentityException(Throwable cause) { + super(cause); + } + + /** + * Create an {@code IdentityException} with a message and cause. + * + * @param message the detail message; can be {@code null} + * @param cause the cause; {@code null} is permitted, and indicates + * that the cause is nonexistent or unknown. + */ + public IdentityException(String message, Throwable cause) { + super(message, cause); + } +} diff --git a/src/java.base/share/classes/java/lang/ref/Reference.java b/src/java.base/share/classes/java/lang/ref/Reference.java index 3f80e93e107..f2fed0a3d32 100644 --- a/src/java.base/share/classes/java/lang/ref/Reference.java +++ b/src/java.base/share/classes/java/lang/ref/Reference.java @@ -31,11 +31,17 @@ import jdk.internal.access.SharedSecrets; import jdk.internal.ref.Cleaner; +import java.util.Objects; + /** * Abstract base class for reference objects. This class defines the * operations common to all reference objects. Because reference objects are * implemented in close cooperation with the garbage collector, this class may * not be subclassed directly. + *
+ * References can only refer to identity objects.
+ * Attempts to create a reference to a {@linkplain Class#isValue() value object}
+ * results in an {@link IdentityException}.
*
* @author Mark Reinhold
* @since 1.2
@@ -498,11 +504,8 @@ protected Object clone() throws CloneNotSupportedException {
}
Reference(T referent, ReferenceQueue super T> queue) {
- if (referent != null && referent.getClass().isValue()) {
- Class> c = referent.getClass();
- throw new IllegalArgumentException("cannot reference a " +
- (c.isPrimitiveClass() ? "primitive class " : "value class ") +
- c.getName());
+ if (referent != null) {
+ Objects.requireIdentity(referent);
}
this.referent = referent;
this.queue = (queue == null) ? ReferenceQueue.NULL : queue;
diff --git a/src/java.base/share/classes/java/util/Objects.java b/src/java.base/share/classes/java/util/Objects.java
index 90b6393c72e..e40085a3cc7 100644
--- a/src/java.base/share/classes/java/util/Objects.java
+++ b/src/java.base/share/classes/java/util/Objects.java
@@ -189,6 +189,66 @@ public static String toIdentityString(Object o) {
return o.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(o));
}
+ /**
+ * Checks that the specified object reference is an identity object.
+ *
+ * @param obj the object reference to check for identity
+ * @param