/* * Copyright (c) 2025, 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. */ import java.lang.invoke.MethodHandle; import java.lang.invoke.MethodHandles; import java.lang.invoke.MethodType; import java.lang.reflect.Proxy; import java.util.concurrent.atomic.AtomicInteger; import org.junit.jupiter.api.Test; import static org.junit.jupiter.api.Assertions.*; /* * @test * @bug 8370839 * @summary Behavior of protected methods in java.lang.Object * @modules java.base/java.lang:+open * @run junit ProtectedObjectMethodsTest */ public class ProtectedObjectMethodsTest { static final MethodHandle OBJECT_CLONE; static final MethodHandle OBJECT_FINALIZE; static { try { var lookup = MethodHandles.privateLookupIn(Object.class, MethodHandles.lookup()); OBJECT_CLONE = lookup.findVirtual(Object.class, "clone", MethodType.methodType(Object.class)); OBJECT_FINALIZE = lookup.findVirtual(Object.class, "finalize", MethodType.methodType(void.class)); } catch (ReflectiveOperationException ex) { throw new ExceptionInInitializerError(ex); } } interface FakeClone { // This method is not related to Object::clone in the JVM, but most // implementations in the Java Language override Object::clone as // covariant overrides FakeClone clone(); } interface TrueClone { // This method is identical to Object::clone in the JVM, that calls // to Object::clone can always call an implementation of this method // if it exists Object clone(); } interface PrimitiveClone { // This method is not related to Object::clone in the JVM, but it can't // be implemented in the Java Language unless using a lambda expression, // due to the Java language covariant override restrictions. int clone(); } // Does not duplicate with Object::clone so it is not proxied @Test void testDistinctClone() throws Throwable { { // This proxy declares FakeClone clone(); which cannot be // invoked through Object::clone. var fake = (FakeClone) Proxy.newProxyInstance(FakeClone.class.getClassLoader(), new Class[] { FakeClone.class }, (p, _, _) -> p); assertSame(fake, fake.clone()); // Verify the default Object::clone behavior (this is not Cloneable) assertThrows(CloneNotSupportedException.class, () -> { var _ = (Object) OBJECT_CLONE.invoke((Object) fake); }); } { // This proxy declares FakeClone clone(); which cannot be // invoked through Object::clone. var fake = (FakeClone) Proxy.newProxyInstance(FakeClone.class.getClassLoader(), new Class[] { FakeClone.class, Cloneable.class }, (p, _, _) -> p); assertSame(fake, fake.clone()); // Verify the default Object::clone behavior (this is Cloneable) var fakeClone = (Object) OBJECT_CLONE.invoke((Object) fake); assertNotSame(fake, fakeClone); assertSame(fake.getClass(), fakeClone.getClass()); assertSame(fakeClone, ((FakeClone) fakeClone).clone()); } { // This proxy declares int clone(); which cannot be // invoked through Object::clone. var instance = (PrimitiveClone) Proxy.newProxyInstance(PrimitiveClone.class.getClassLoader(), new Class[] { PrimitiveClone.class }, (_, _, _) -> 42); assertEquals(42, instance.clone()); // Verify the default Object::clone behavior (this is not Cloneable) assertThrows(CloneNotSupportedException.class, () -> { var _ = (Object) OBJECT_CLONE.invoke((Object) instance); }); } { // This proxy declares int clone(); which cannot be // invoked through Object::clone var instance = (PrimitiveClone) Proxy.newProxyInstance(PrimitiveClone.class.getClassLoader(), new Class[] { PrimitiveClone.class, Cloneable.class }, (_, _, _) -> 76); assertEquals(76, instance.clone()); // Verify the default Object::clone behavior (this is Cloneable) var clone = (Object) OBJECT_CLONE.invoke((Object) instance); assertNotSame(instance, clone); assertSame(instance.getClass(), clone.getClass()); assertEquals(76, ((PrimitiveClone) clone).clone()); } } // Duplicates with Object::clone so it is proxied @Test void testDuplicateClone() throws Throwable { { // This proxy declares Object clone();, which // accidentally overrides Object::clone var instance = (TrueClone) Proxy.newProxyInstance(TrueClone.class.getClassLoader(), new Class[] { TrueClone.class }, (p, _, _) -> p); assertSame(instance, instance.clone()); // Verify Object::clone is overridden assertSame(instance, (Object) OBJECT_CLONE.invoke((Object) instance)); } { // This proxy declares Object clone(); and FakeClone clone();. // They are considered duplicate methods and dispatched equivalently. // Object clone() accidentally overrides Object::clone, so now // FakeClone clone() can be called through Object::clone var instance = Proxy.newProxyInstance(TrueClone.class.getClassLoader(), new Class[] { TrueClone.class, FakeClone.class }, (p, _, _) -> p); assertSame(instance, ((FakeClone) instance).clone()); assertSame(instance, ((TrueClone) instance).clone()); // Verify Object::clone is overridden assertSame(instance, (Object) OBJECT_CLONE.invoke((Object) instance)); } } interface FalseFinalize { // This method is not related to Object::finalize in the JVM, but it can't // be implemented in the Java Language unless using a lambda expression, // due to the Java language covariant override restrictions. int finalize(); } interface TrueFinalize { // This method is identical to Object::finalize in the JVM, that calls // to Object::finalize can always call an implementation of this method // if it exists void finalize(); } @Test void testDistinctFinalize() throws Throwable { AtomicInteger invokeCount = new AtomicInteger(); // This proxy declares int finalize(), which cannot be // invoked through Object::finalize. var instance = Proxy.newProxyInstance(FalseFinalize.class.getClassLoader(), new Class[] { FalseFinalize.class }, (_, _, _) -> invokeCount.incrementAndGet()); // Verify the default Object::finalize behavior OBJECT_FINALIZE.invoke(instance); assertEquals(0, invokeCount.get()); assertEquals(1, ((FalseFinalize) instance).finalize()); } @Test void testDuplicateFinalize() throws Throwable { AtomicInteger invokeCount = new AtomicInteger(); // This proxy declares void finalize(), which can be // invoked through Object::finalize. var instance = Proxy.newProxyInstance(TrueFinalize.class.getClassLoader(), new Class[] { TrueFinalize.class }, (_, _, _) -> invokeCount.incrementAndGet()); // Verify the overridden Object::finalize behavior OBJECT_FINALIZE.invoke(instance); assertEquals(1, invokeCount.get()); ((TrueFinalize) instance).finalize(); assertEquals(2, invokeCount.get()); } }