| /* | |
| * Copyright (c) 1994, 2024, 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. Oracle designates this | |
| * particular file as subject to the "Classpath" exception as provided | |
| * by Oracle in the LICENSE file that accompanied this code. | |
| * | |
| * 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; | |
| import jdk.internal.vm.annotation.IntrinsicCandidate; | |
| /** | |
| * Class {@code Object} is the root of the class hierarchy. | |
| * Every class has {@code Object} as a superclass. All objects, | |
| * including arrays, implement the methods of this class. | |
| * | |
| * @see java.lang.Class | |
| * @since 1.0 | |
| */ | |
| public class Object { | |
| /** | |
| * Constructs a new object. | |
| */ | |
| @IntrinsicCandidate | |
| public Object() {} | |
| /** | |
| * Returns the runtime class of this {@code Object}. The returned | |
| * {@code Class} object is the object that is locked by {@code | |
| * static synchronized} methods of the represented class. | |
| * | |
| * <p><b>The actual result type is {@code Class<? extends |X|>} | |
| * where {@code |X|} is the erasure of the static type of the | |
| * expression on which {@code getClass} is called.</b> For | |
| * example, no cast is required in this code fragment:</p> | |
| * | |
| * <p> | |
| * {@code Number n = 0; }<br> | |
| * {@code Class<? extends Number> c = n.getClass(); } | |
| * </p> | |
| * | |
| * @return The {@code Class} object that represents the runtime | |
| * class of this object. | |
| * @jls 15.8.2 Class Literals | |
| */ | |
| @IntrinsicCandidate | |
| public final native Class<?> getClass(); | |
| /** | |
| * {@return a hash code value for this object} This method is | |
| * supported for the benefit of hash tables such as those provided by | |
| * {@link java.util.HashMap}. | |
| * <p> | |
| * The general contract of {@code hashCode} is: | |
| * <ul> | |
| * <li>Whenever it is invoked on the same object more than once during | |
| * an execution of a Java application, the {@code hashCode} method | |
| * must consistently return the same integer, provided no information | |
| * used in {@code equals} comparisons on the object is modified. | |
| * This integer need not remain consistent from one execution of an | |
| * application to another execution of the same application. | |
| * <li>If two objects are equal according to the {@link | |
| * #equals(Object) equals} method, then calling the {@code | |
| * hashCode} method on each of the two objects must produce the | |
| * same integer result. | |
| * <li>It is <em>not</em> required that if two objects are unequal | |
| * according to the {@link #equals(Object) equals} method, then | |
| * calling the {@code hashCode} method on each of the two objects | |
| * must produce distinct integer results. However, the programmer | |
| * should be aware that producing distinct integer results for | |
| * unequal objects may improve the performance of hash tables. | |
| * </ul> | |
| * | |
| * @implSpec | |
| * As far as is reasonably practical, the {@code hashCode} method defined | |
| * by class {@code Object} returns distinct integers for distinct objects. | |
| * | |
| * @apiNote | |
| * The {@link java.util.Objects#hash(Object...) hash} and {@link | |
| * java.util.Objects#hashCode(Object) hashCode} methods of {@link | |
| * java.util.Objects} can be used to help construct simple hash codes. | |
| * | |
| * @see java.lang.Object#equals(java.lang.Object) | |
| * @see java.lang.System#identityHashCode | |
| */ | |
| @IntrinsicCandidate | |
| public native int hashCode(); | |
| /** | |
| * Indicates whether some other object is "equal to" this one. | |
| * <p> | |
| * The {@code equals} method implements an <dfn>{@index "equivalence relation"}</dfn> | |
| * on non-null object references: | |
| * <ul> | |
| * <li>It is <i>reflexive</i>: for any non-null reference value | |
| * {@code x}, {@code x.equals(x)} should return | |
| * {@code true}. | |
| * <li>It is <i>symmetric</i>: for any non-null reference values | |
| * {@code x} and {@code y}, {@code x.equals(y)} | |
| * should return {@code true} if and only if | |
| * {@code y.equals(x)} returns {@code true}. | |
| * <li>It is <i>transitive</i>: for any non-null reference values | |
| * {@code x}, {@code y}, and {@code z}, if | |
| * {@code x.equals(y)} returns {@code true} and | |
| * {@code y.equals(z)} returns {@code true}, then | |
| * {@code x.equals(z)} should return {@code true}. | |
| * <li>It is <i>consistent</i>: for any non-null reference values | |
| * {@code x} and {@code y}, multiple invocations of | |
| * {@code x.equals(y)} consistently return {@code true} | |
| * or consistently return {@code false}, provided no | |
| * information used in {@code equals} comparisons on the | |
| * objects is modified. | |
| * <li>For any non-null reference value {@code x}, | |
| * {@code x.equals(null)} should return {@code false}. | |
| * </ul> | |
| * | |
| * <p> | |
| * An equivalence relation partitions the elements it operates on | |
| * into <i>equivalence classes</i>; all the members of an | |
| * equivalence class are equal to each other. Members of an | |
| * equivalence class are substitutable for each other, at least | |
| * for some purposes. | |
| * | |
| * @implSpec | |
| * The {@code equals} method for class {@code Object} implements | |
| * the most discriminating possible equivalence relation on objects; | |
| * that is, for any non-null reference values {@code x} and | |
| * {@code y}, this method returns {@code true} if and only | |
| * if {@code x} and {@code y} refer to the same object | |
| * ({@code x == y} has the value {@code true}). | |
| * | |
| * In other words, under the reference equality equivalence | |
| * relation, each equivalence class only has a single element. | |
| * | |
| * @apiNote | |
| * It is generally necessary to override the {@link #hashCode() hashCode} | |
| * method whenever this method is overridden, so as to maintain the | |
| * general contract for the {@code hashCode} method, which states | |
| * that equal objects must have equal hash codes. | |
| * <p>The two-argument {@link java.util.Objects#equals(Object, | |
| * Object) Objects.equals} method implements an equivalence relation | |
| * on two possibly-null object references. | |
| * | |
| * @param obj the reference object with which to compare. | |
| * @return {@code true} if this object is the same as the obj | |
| * argument; {@code false} otherwise. | |
| * @see #hashCode() | |
| * @see java.util.HashMap | |
| */ | |
| public boolean equals(Object obj) { | |
| return (this == obj); | |
| } | |
| /** | |
| * Creates and returns a copy of this object. The precise meaning | |
| * of "copy" may depend on the class of the object. The general | |
| * intent is that, for any object {@code x}, the expression: | |
| * <blockquote> | |
| * <pre> | |
| * x.clone() != x</pre></blockquote> | |
| * will be true, and that the expression: | |
| * <blockquote> | |
| * <pre> | |
| * x.clone().getClass() == x.getClass()</pre></blockquote> | |
| * will be {@code true}, but these are not absolute requirements. | |
| * While it is typically the case that: | |
| * <blockquote> | |
| * <pre> | |
| * x.clone().equals(x)</pre></blockquote> | |
| * will be {@code true}, this is not an absolute requirement. | |
| * <p> | |
| * By convention, the returned object should be obtained by calling | |
| * {@code super.clone}. If a class and all of its superclasses (except | |
| * {@code Object}) obey this convention, it will be the case that | |
| * {@code x.clone().getClass() == x.getClass()}. | |
| * <p> | |
| * By convention, the object returned by this method should be independent | |
| * of this object (which is being cloned). To achieve this independence, | |
| * it may be necessary to modify one or more fields of the object returned | |
| * by {@code super.clone} before returning it. Typically, this means | |
| * copying any mutable objects that comprise the internal "deep structure" | |
| * of the object being cloned and replacing the references to these | |
| * objects with references to the copies. If a class contains only | |
| * primitive fields or references to immutable objects, then it is usually | |
| * the case that no fields in the object returned by {@code super.clone} | |
| * need to be modified. | |
| * | |
| * @implSpec | |
| * The method {@code clone} for class {@code Object} performs a | |
| * specific cloning operation. First, if the class of this object does | |
| * not implement the interface {@code Cloneable}, then a | |
| * {@code CloneNotSupportedException} is thrown. Note that all arrays | |
| * are considered to implement the interface {@code Cloneable} and that | |
| * the return type of the {@code clone} method of an array type {@code T[]} | |
| * is {@code T[]} where T is any reference or primitive type. | |
| * Otherwise, this method creates a new instance of the class of this | |
| * object and initializes all its fields with exactly the contents of | |
| * the corresponding fields of this object, as if by assignment; the | |
| * contents of the fields are not themselves cloned. Thus, this method | |
| * performs a "shallow copy" of this object, not a "deep copy" operation. | |
| * <p> | |
| * The class {@code Object} does not itself implement the interface | |
| * {@code Cloneable}, so calling the {@code clone} method on an object | |
| * whose class is {@code Object} will result in throwing an | |
| * exception at run time. | |
| * | |
| * @return a clone of this instance. | |
| * @throws CloneNotSupportedException if the object's class does not | |
| * support the {@code Cloneable} interface. Subclasses | |
| * that override the {@code clone} method can also | |
| * throw this exception to indicate that an instance cannot | |
| * be cloned. | |
| * @see java.lang.Cloneable | |
| */ | |
| @IntrinsicCandidate | |
| protected native Object clone() throws CloneNotSupportedException; | |
| /** | |
| * {@return a string representation of the object} | |
| * | |
| * Satisfying this method's contract implies a non-{@code null} | |
| * result must be returned. | |
| * | |
| * @apiNote | |
| * In general, the | |
| * {@code toString} method returns a string that | |
| * "textually represents" this object. The result should | |
| * be a concise but informative representation that is easy for a | |
| * person to read. | |
| * It is recommended that all subclasses override this method. | |
| * The string output is not necessarily stable over time or across | |
| * JVM invocations. | |
| * @implSpec | |
| * The {@code toString} method for class {@code Object} | |
| * returns a string consisting of the name of the class of which the | |
| * object is an instance, the at-sign character `{@code @}', and | |
| * the unsigned hexadecimal representation of the hash code of the | |
| * object. In other words, this method returns a string equal to the | |
| * value of: | |
| * {@snippet lang=java : | |
| * getClass().getName() + '@' + Integer.toHexString(hashCode()) | |
| * } | |
| * The {@link java.util.Objects#toIdentityString(Object) | |
| * Objects.toIdentityString} method returns the string for an | |
| * object equal to the string that would be returned if neither | |
| * the {@code toString} nor {@code hashCode} methods were | |
| * overridden by the object's class. | |
| */ | |
| public String toString() { | |
| return getClass().getName() + "@" + Integer.toHexString(hashCode()); | |
| } | |
| /** | |
| * Wakes up a single thread that is waiting on this object's | |
| * monitor. If any threads are waiting on this object, one of them | |
| * is chosen to be awakened. The choice is arbitrary and occurs at | |
| * the discretion of the implementation. A thread waits on an object's | |
| * monitor by calling one of the {@code wait} methods. | |
| * <p> | |
| * The awakened thread will not be able to proceed until the current | |
| * thread relinquishes the lock on this object. The awakened thread will | |
| * compete in the usual manner with any other threads that might be | |
| * actively competing to synchronize on this object; for example, the | |
| * awakened thread enjoys no reliable privilege or disadvantage in being | |
| * the next thread to lock this object. | |
| * <p> | |
| * This method should only be called by a thread that is the owner | |
| * of this object's monitor. A thread becomes the owner of the | |
| * object's monitor in one of three ways: | |
| * <ul> | |
| * <li>By executing a synchronized instance method of that object. | |
| * <li>By executing the body of a {@code synchronized} statement | |
| * that synchronizes on the object. | |
| * <li>For objects of type {@code Class,} by executing a | |
| * static synchronized method of that class. | |
| * </ul> | |
| * <p> | |
| * Only one thread at a time can own an object's monitor. | |
| * | |
| * @throws IllegalMonitorStateException if the current thread is not | |
| * the owner of this object's monitor. | |
| * @see java.lang.Object#notifyAll() | |
| * @see java.lang.Object#wait() | |
| */ | |
| @IntrinsicCandidate | |
| public final native void notify(); | |
| /** | |
| * Wakes up all threads that are waiting on this object's monitor. A | |
| * thread waits on an object's monitor by calling one of the | |
| * {@code wait} methods. | |
| * <p> | |
| * The awakened threads will not be able to proceed until the current | |
| * thread relinquishes the lock on this object. The awakened threads | |
| * will compete in the usual manner with any other threads that might | |
| * be actively competing to synchronize on this object; for example, | |
| * the awakened threads enjoy no reliable privilege or disadvantage in | |
| * being the next thread to lock this object. | |
| * <p> | |
| * This method should only be called by a thread that is the owner | |
| * of this object's monitor. See the {@code notify} method for a | |
| * description of the ways in which a thread can become the owner of | |
| * a monitor. | |
| * | |
| * @throws IllegalMonitorStateException if the current thread is not | |
| * the owner of this object's monitor. | |
| * @see java.lang.Object#notify() | |
| * @see java.lang.Object#wait() | |
| */ | |
| @IntrinsicCandidate | |
| public final native void notifyAll(); | |
| /** | |
| * Causes the current thread to wait until it is awakened, typically | |
| * by being <em>notified</em> or <em>interrupted</em>. | |
| * <p> | |
| * In all respects, this method behaves as if {@code wait(0L, 0)} | |
| * had been called. See the specification of the {@link #wait(long, int)} method | |
| * for details. | |
| * | |
| * @throws IllegalMonitorStateException if the current thread is not | |
| * the owner of the object's monitor | |
| * @throws InterruptedException if any thread interrupted the current thread before or | |
| * while the current thread was waiting. The <em>interrupted status</em> of the | |
| * current thread is cleared when this exception is thrown. | |
| * @see #notify() | |
| * @see #notifyAll() | |
| * @see #wait(long) | |
| * @see #wait(long, int) | |
| */ | |
| public final void wait() throws InterruptedException { | |
| wait(0L); | |
| } | |
| /** | |
| * Causes the current thread to wait until it is awakened, typically | |
| * by being <em>notified</em> or <em>interrupted</em>, or until a | |
| * certain amount of real time has elapsed. | |
| * <p> | |
| * In all respects, this method behaves as if {@code wait(timeoutMillis, 0)} | |
| * had been called. See the specification of the {@link #wait(long, int)} method | |
| * for details. | |
| * | |
| * @param timeoutMillis the maximum time to wait, in milliseconds | |
| * @throws IllegalArgumentException if {@code timeoutMillis} is negative | |
| * @throws IllegalMonitorStateException if the current thread is not | |
| * the owner of the object's monitor | |
| * @throws InterruptedException if any thread interrupted the current thread before or | |
| * while the current thread was waiting. The <em>interrupted status</em> of the | |
| * current thread is cleared when this exception is thrown. | |
| * @see #notify() | |
| * @see #notifyAll() | |
| * @see #wait() | |
| * @see #wait(long, int) | |
| */ | |
| public final void wait(long timeoutMillis) throws InterruptedException { | |
| if (timeoutMillis < 0) { | |
| throw new IllegalArgumentException("timeout value is negative"); | |
| } | |
| if (Thread.currentThread() instanceof VirtualThread vthread) { | |
| try { | |
| wait0(timeoutMillis); | |
| } catch (InterruptedException e) { | |
| // virtual thread's interrupt status needs to be cleared | |
| vthread.getAndClearInterrupt(); | |
| throw e; | |
| } | |
| } else { | |
| wait0(timeoutMillis); | |
| } | |
| } | |
| // final modifier so method not in vtable | |
| private final native void wait0(long timeoutMillis) throws InterruptedException; | |
| /** | |
| * Causes the current thread to wait until it is awakened, typically | |
| * by being <em>notified</em> or <em>interrupted</em>, or until a | |
| * certain amount of real time has elapsed. | |
| * <p> | |
| * The current thread must own this object's monitor lock. See the | |
| * {@link #notify notify} method for a description of the ways in which | |
| * a thread can become the owner of a monitor lock. | |
| * <p> | |
| * This method causes the current thread (referred to here as <var>T</var>) to | |
| * place itself in the wait set for this object and then to relinquish any | |
| * and all synchronization claims on this object. Note that only the locks | |
| * on this object are relinquished; any other objects on which the current | |
| * thread may be synchronized remain locked while the thread waits. | |
| * <p> | |
| * Thread <var>T</var> then becomes disabled for thread scheduling purposes | |
| * and lies dormant until one of the following occurs: | |
| * <ul> | |
| * <li>Some other thread invokes the {@code notify} method for this | |
| * object and thread <var>T</var> happens to be arbitrarily chosen as | |
| * the thread to be awakened. | |
| * <li>Some other thread invokes the {@code notifyAll} method for this | |
| * object. | |
| * <li>Some other thread {@linkplain Thread#interrupt() interrupts} | |
| * thread <var>T</var>. | |
| * <li>The specified amount of real time has elapsed, more or less. | |
| * The amount of real time, in nanoseconds, is given by the expression | |
| * {@code 1000000 * timeoutMillis + nanos}. If {@code timeoutMillis} and {@code nanos} | |
| * are both zero, then real time is not taken into consideration and the | |
| * thread waits until awakened by one of the other causes. | |
| * <li>Thread <var>T</var> is awakened spuriously. (See below.) | |
| * </ul> | |
| * <p> | |
| * The thread <var>T</var> is then removed from the wait set for this | |
| * object and re-enabled for thread scheduling. It competes in the | |
| * usual manner with other threads for the right to synchronize on the | |
| * object; once it has regained control of the object, all its | |
| * synchronization claims on the object are restored to the status quo | |
| * ante - that is, to the situation as of the time that the {@code wait} | |
| * method was invoked. Thread <var>T</var> then returns from the | |
| * invocation of the {@code wait} method. Thus, on return from the | |
| * {@code wait} method, the synchronization state of the object and of | |
| * thread {@code T} is exactly as it was when the {@code wait} method | |
| * was invoked. | |
| * <p> | |
| * A thread can wake up without being notified, interrupted, or timing out, a | |
| * so-called <em>spurious wakeup</em>. While this will rarely occur in practice, | |
| * applications must guard against it by testing for the condition that should | |
| * have caused the thread to be awakened, and continuing to wait if the condition | |
| * is not satisfied. See the example below. | |
| * <p> | |
| * For more information on this topic, see section 14.2, | |
| * "Condition Queues," in Brian Goetz and others' <cite>Java Concurrency | |
| * in Practice</cite> (Addison-Wesley, 2006) or Item 81 in Joshua | |
| * Bloch's <cite>Effective Java, Third Edition</cite> (Addison-Wesley, | |
| * 2018). | |
| * <p> | |
| * If the current thread is {@linkplain java.lang.Thread#interrupt() interrupted} | |
| * by any thread before or while it is waiting, then an {@code InterruptedException} | |
| * is thrown. The <em>interrupted status</em> of the current thread is cleared when | |
| * this exception is thrown. This exception is not thrown until the lock status of | |
| * this object has been restored as described above. | |
| * | |
| * @apiNote | |
| * The recommended approach to waiting is to check the condition being awaited in | |
| * a {@code while} loop around the call to {@code wait}, as shown in the example | |
| * below. Among other things, this approach avoids problems that can be caused | |
| * by spurious wakeups. | |
| * | |
| * {@snippet lang=java : | |
| * synchronized (obj) { | |
| * while ( <condition does not hold and timeout not exceeded> ) { | |
| * long timeoutMillis = ... ; // recompute timeout values | |
| * int nanos = ... ; | |
| * obj.wait(timeoutMillis, nanos); | |
| * } | |
| * ... // Perform action appropriate to condition or timeout | |
| * } | |
| * } | |
| * | |
| * @param timeoutMillis the maximum time to wait, in milliseconds | |
| * @param nanos additional time, in nanoseconds, in the range 0-999999 inclusive | |
| * @throws IllegalArgumentException if {@code timeoutMillis} is negative, | |
| * or if the value of {@code nanos} is out of range | |
| * @throws IllegalMonitorStateException if the current thread is not | |
| * the owner of the object's monitor | |
| * @throws InterruptedException if any thread interrupted the current thread before or | |
| * while the current thread was waiting. The <em>interrupted status</em> of the | |
| * current thread is cleared when this exception is thrown. | |
| * @see #notify() | |
| * @see #notifyAll() | |
| * @see #wait() | |
| * @see #wait(long) | |
| */ | |
| public final void wait(long timeoutMillis, int nanos) throws InterruptedException { | |
| if (timeoutMillis < 0) { | |
| throw new IllegalArgumentException("timeoutMillis value is negative"); | |
| } | |
| if (nanos < 0 || nanos > 999999) { | |
| throw new IllegalArgumentException( | |
| "nanosecond timeout value out of range"); | |
| } | |
| if (nanos > 0 && timeoutMillis < Long.MAX_VALUE) { | |
| timeoutMillis++; | |
| } | |
| wait(timeoutMillis); | |
| } | |
| /** | |
| * Called by the garbage collector on an object when garbage collection | |
| * determines that there are no more references to the object. | |
| * A subclass overrides the {@code finalize} method to dispose of | |
| * system resources or to perform other cleanup. | |
| * <p> | |
| * <b>When running in a Java virtual machine in which finalization has been | |
| * disabled or removed, the garbage collector will never call | |
| * {@code finalize()}. In a Java virtual machine in which finalization is | |
| * enabled, the garbage collector might call {@code finalize} only after an | |
| * indefinite delay.</b> | |
| * <p> | |
| * The general contract of {@code finalize} is that it is invoked | |
| * if and when the Java virtual | |
| * machine has determined that there is no longer any | |
| * means by which this object can be accessed by any thread that has | |
| * not yet died, except as a result of an action taken by the | |
| * finalization of some other object or class which is ready to be | |
| * finalized. The {@code finalize} method may take any action, including | |
| * making this object available again to other threads; the usual purpose | |
| * of {@code finalize}, however, is to perform cleanup actions before | |
| * the object is irrevocably discarded. For example, the finalize method | |
| * for an object that represents an input/output connection might perform | |
| * explicit I/O transactions to break the connection before the object is | |
| * permanently discarded. | |
| * <p> | |
| * The {@code finalize} method of class {@code Object} performs no | |
| * special action; it simply returns normally. Subclasses of | |
| * {@code Object} may override this definition. | |
| * <p> | |
| * The Java programming language does not guarantee which thread will | |
| * invoke the {@code finalize} method for any given object. It is | |
| * guaranteed, however, that the thread that invokes finalize will not | |
| * be holding any user-visible synchronization locks when finalize is | |
| * invoked. If an uncaught exception is thrown by the finalize method, | |
| * the exception is ignored and finalization of that object terminates. | |
| * <p> | |
| * After the {@code finalize} method has been invoked for an object, no | |
| * further action is taken until the Java virtual machine has again | |
| * determined that there is no longer any means by which this object can | |
| * be accessed by any thread that has not yet died, including possible | |
| * actions by other objects or classes which are ready to be finalized, | |
| * at which point the object may be discarded. | |
| * <p> | |
| * The {@code finalize} method is never invoked more than once by a Java | |
| * virtual machine for any given object. | |
| * <p> | |
| * Any exception thrown by the {@code finalize} method causes | |
| * the finalization of this object to be halted, but is otherwise | |
| * ignored. | |
| * | |
| * @apiNote | |
| * Classes that embed non-heap resources have many options | |
| * for cleanup of those resources. The class must ensure that the | |
| * lifetime of each instance is longer than that of any resource it embeds. | |
| * {@link java.lang.ref.Reference#reachabilityFence} can be used to ensure that | |
| * objects remain reachable while resources embedded in the object are in use. | |
| * <p> | |
| * A subclass should avoid overriding the {@code finalize} method | |
| * unless the subclass embeds non-heap resources that must be cleaned up | |
| * before the instance is collected. | |
| * Finalizer invocations are not automatically chained, unlike constructors. | |
| * If a subclass overrides {@code finalize} it must invoke the superclass | |
| * finalizer explicitly. | |
| * To guard against exceptions prematurely terminating the finalize chain, | |
| * the subclass should use a {@code try-finally} block to ensure | |
| * {@code super.finalize()} is always invoked. For example, | |
| * {@snippet lang="java": | |
| * @Override | |
| * protected void finalize() throws Throwable { | |
| * try { | |
| * ... // cleanup subclass state | |
| * } finally { | |
| * super.finalize(); | |
| * } | |
| * } | |
| * } | |
| * | |
| * @deprecated Finalization is deprecated and subject to removal in a future | |
| * release. The use of finalization can lead to problems with security, | |
| * performance, and reliability. | |
| * See <a href="https://openjdk.org/jeps/421">JEP 421</a> for | |
| * discussion and alternatives. | |
| * <p> | |
| * Subclasses that override {@code finalize} to perform cleanup should use | |
| * alternative cleanup mechanisms and remove the {@code finalize} method. | |
| * Use {@link java.lang.ref.Cleaner} and | |
| * {@link java.lang.ref.PhantomReference} as safer ways to release resources | |
| * when an object becomes unreachable. Alternatively, add a {@code close} | |
| * method to explicitly release resources, and implement | |
| * {@code AutoCloseable} to enable use of the {@code try}-with-resources | |
| * statement. | |
| * <p> | |
| * This method will remain in place until finalizers have been removed from | |
| * most existing code. | |
| * | |
| * @throws Throwable the {@code Exception} raised by this method | |
| * @see java.lang.ref.WeakReference | |
| * @see java.lang.ref.PhantomReference | |
| * @jls 12.6 Finalization of Class Instances | |
| */ | |
| @Deprecated(since="9", forRemoval=true) | |
| protected void finalize() throws Throwable { } | |
| } |