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  * 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

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 package java.lang;

 /**

  * 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.

  *

  * @author  unascribed

  * @see     java.lang.Class

  * @since   JDK1.0

  */

 public class Object {

     private static native void registerNatives();

     static {

         registerNatives();

     }

     /**

      * 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.

      * @see    Class Literals, section 15.8.2 of

      *         <cite>The Java&trade; Language Specification</cite>.

      */

     public final native Class<?> getClass();

     /**

      * Returns a hash code value for the 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 {@code equals(Object)}

      *     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 java.lang.Object#equals(java.lang.Object)}

      *     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>

      * <p>

      * As much as is reasonably practical, the hashCode method defined by

      * class {@code Object} does return distinct integers for distinct

      * objects. (This is typically implemented by converting the internal

      * address of the object into an integer, but this implementation

      * technique is not required by the

      * Java<font size="-2"><sup>TM</sup></font> programming language.)

      *

      * @return  a hash code value for this object.

      * @see     java.lang.Object#equals(java.lang.Object)

      * @see     java.lang.System#identityHashCode

      */

     public native int hashCode();

     /**

      * Indicates whether some other object is "equal to" this one.

      * <p>

      * The {@code equals} method implements an equivalence relation

      * 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>

      * 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}).

      * <p>

      * Note that it is generally necessary to override the {@code 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.

      *

      * @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.

      * <p>

      * 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.

      * @exception  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

      */

     protected native Object clone() throws CloneNotSupportedException;

     /**

      * Returns a string representation of the object. 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.

      * <p>

      * 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:

      * <blockquote>

      * <pre>

      * getClass().getName() + '@' + Integer.toHexString(hashCode())

      * </pre></blockquote>

      *

      * @return  a string representation of the object.

      */

     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

      *     synchronized static method of that class.

      * </ul>

      * <p>

      * Only one thread at a time can own an object's monitor.

      *

      * @exception  IllegalMonitorStateException  if the current thread is not

      *               the owner of this object's monitor.

      * @see        java.lang.Object#notifyAll()

      * @see        java.lang.Object#wait()

      */

     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.

      *

      * @exception  IllegalMonitorStateException  if the current thread is not

      *               the owner of this object's monitor.

      * @see        java.lang.Object#notify()

      * @see        java.lang.Object#wait()

      */

     public final native void notifyAll();

     /**

      * Causes the current thread to wait until either another thread invokes the

      * {@link java.lang.Object#notify()} method or the

      * {@link java.lang.Object#notifyAll()} method for this object, or a

      * specified amount of time has elapsed.

      * <p>

      * The current thread must own this object's monitor.

      * <p>

      * This method causes the current thread (call it <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. Thread <var>T</var>

      * becomes disabled for thread scheduling purposes and lies dormant

      * until one of four things happens:

      * <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.  If

      * {@code timeout} is zero, however, then real time is not taken into

      * consideration and the thread simply waits until notified.

      * </ul>

      * The thread <var>T</var> is then removed from the wait set for this

      * object and re-enabled for thread scheduling. It then competes in the

      * usual manner with other threads for the right to synchronize on the

      * object; once it has gained 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 also wake up without being notified, interrupted, or

      * timing out, a so-called <i>spurious wakeup</i>.  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.  In other words,

      * waits should always occur in loops, like this one:

      * <pre>

      *     synchronized (obj) {

      *         while (<condition does not hold>)

      *             obj.wait(timeout);

      *         ... // Perform action appropriate to condition

      *     }

      * </pre>

      * (For more information on this topic, see Section 3.2.3 in Doug Lea's

      * "Concurrent Programming in Java (Second Edition)" (Addison-Wesley,

      * 2000), or Item 50 in Joshua Bloch's "Effective Java Programming

      * Language Guide" (Addison-Wesley, 2001).

      *

      * <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.  This exception is not

      * thrown until the lock status of this object has been restored as

      * described above.

      *

      * <p>

      * Note that the {@code wait} method, as it places the current thread

      * into the wait set for this object, unlocks only this object; any

      * other objects on which the current thread may be synchronized remain

      * locked while the thread waits.

      * <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.

      *

      * @param      timeout   the maximum time to wait in milliseconds.

      * @exception  IllegalArgumentException      if the value of timeout is

      *               negative.

      * @exception  IllegalMonitorStateException  if the current thread is not

      *               the owner of the object's monitor.

      * @exception  InterruptedException if any thread interrupted the

      *             current thread before or while the current thread

      *             was waiting for a notification.  The <i>interrupted

      *             status</i> of the current thread is cleared when

      *             this exception is thrown.

      * @see        java.lang.Object#notify()

      * @see        java.lang.Object#notifyAll()

      */

     public final native void wait(long timeout) throws InterruptedException;

     /**

      * Causes the current thread to wait until another thread invokes the

      * {@link java.lang.Object#notify()} method or the

      * {@link java.lang.Object#notifyAll()} method for this object, or

      * some other thread interrupts the current thread, or a certain

      * amount of real time has elapsed.

      * <p>

      * This method is similar to the {@code wait} method of one

      * argument, but it allows finer control over the amount of time to

      * wait for a notification before giving up. The amount of real time,

      * measured in nanoseconds, is given by:

      * <blockquote>

      * <pre>

      * 1000000*timeout+nanos</pre></blockquote>

      * <p>

      * In all other respects, this method does the same thing as the

      * method {@link #wait(long)} of one argument. In particular,

      * {@code wait(0, 0)} means the same thing as {@code wait(0)}.

      * <p>

      * The current thread must own this object's monitor. The thread

      * releases ownership of this monitor and waits until either of the

      * following two conditions has occurred:

      * <ul>

      * <li>Another thread notifies threads waiting on this object's monitor

      *     to wake up either through a call to the {@code notify} method

      *     or the {@code notifyAll} method.

      * <li>The timeout period, specified by {@code timeout}

      *     milliseconds plus {@code nanos} nanoseconds arguments, has

      *     elapsed.

      * </ul>

      * <p>

      * The thread then waits until it can re-obtain ownership of the

      * monitor and resumes execution.

      * <p>

      * As in the one argument version, interrupts and spurious wakeups are

      * possible, and this method should always be used in a loop:

      * <pre>

      *     synchronized (obj) {

      *         while (<condition does not hold>)

      *             obj.wait(timeout, nanos);

      *         ... // Perform action appropriate to condition

      *     }

      * </pre>

      * 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.

      *

      * @param      timeout   the maximum time to wait in milliseconds.

      * @param      nanos      additional time, in nanoseconds range

      *                       0-999999.

      * @exception  IllegalArgumentException      if the value of timeout is

      *                      negative or the value of nanos is

      *                      not in the range 0-999999.

      * @exception  IllegalMonitorStateException  if the current thread is not

      *               the owner of this object's monitor.

      * @exception  InterruptedException if any thread interrupted the

      *             current thread before or while the current thread

      *             was waiting for a notification.  The <i>interrupted

      *             status</i> of the current thread is cleared when

      *             this exception is thrown.

      */

     public final void wait(long timeout, int nanos) throws InterruptedException {

         if (timeout < 0) {

             throw new IllegalArgumentException("timeout value is negative");

         }

         if (nanos < 0 || nanos > 999999) {

             throw new IllegalArgumentException(

                                 "nanosecond timeout value out of range");

         }

         if (nanos >= 500000 || (nanos != 0 && timeout == 0)) {

             timeout++;

         }

         wait(timeout);

     }

     /**

      * Causes the current thread to wait until another thread invokes the

      * {@link java.lang.Object#notify()} method or the

      * {@link java.lang.Object#notifyAll()} method for this object.

      * In other words, this method behaves exactly as if it simply

      * performs the call {@code wait(0)}.

      * <p>

      * The current thread must own this object's monitor. The thread

      * releases ownership of this monitor and waits until another thread

      * notifies threads waiting on this object's monitor to wake up

      * either through a call to the {@code notify} method or the

      * {@code notifyAll} method. The thread then waits until it can

      * re-obtain ownership of the monitor and resumes execution.

      * <p>

      * As in the one argument version, interrupts and spurious wakeups are

      * possible, and this method should always be used in a loop:

      * <pre>

      *     synchronized (obj) {

      *         while (<condition does not hold>)

      *             obj.wait();

      *         ... // Perform action appropriate to condition

      *     }

      * </pre>

      * 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.

      *

      * @exception  IllegalMonitorStateException  if the current thread is not

      *               the owner of the object's monitor.

      * @exception  InterruptedException if any thread interrupted the

      *             current thread before or while the current thread

      *             was waiting for a notification.  The <i>interrupted

      *             status</i> of the current thread is cleared when

      *             this exception is thrown.

      * @see        java.lang.Object#notify()

      * @see        java.lang.Object#notifyAll()

      */

     public final void wait() throws InterruptedException {

         wait(0);

     }

     /**

      * 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>

      * The general contract of {@code finalize} is that it is invoked

      * if and when the Java<font size="-2"><sup>TM</sup></font> 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.

      *

      * @throws Throwable the {@code Exception} raised by this method

      */

     protected void finalize() throws Throwable { }

 }