java.lang.Object Maven / Gradle / Ivy
/*
This is not an official specification document, and usage is restricted.
NOTICE
(c) 2005-2007 Sun Microsystems, Inc. All Rights Reserved.
Neither this file nor any files generated from it describe a complete
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Sun Microsystems Inc. owns the copyright in this file and it is provided
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files generated from it may be used to generate other informative
documentation, such as a unified set of documents of API signatures for
a platform that includes technologies expressed as Java APIs. The file
may also be used to produce "compilation stubs," which allow
applications to be compiled and validated for such platforms.
Any work generated from this file, such as unified javadocs or compiled
stub files, must be accompanied by this notice in its entirety.
This work corresponds to the API signatures of JSR 219: Foundation
Profile 1.1. In the event of a discrepency between this work and the
JSR 219 specification, which is available at
http://www.jcp.org/en/jsr/detail?id=219, the latter takes precedence.
*/
package java.lang;
/**
* Class Object is the root of the class hierarchy.
* Every class has Object as a superclass. All objects,
* including arrays, implement the methods of this class.
*
* @author unascribed
* @version 1.55, 05/03/00
* @see java.lang.Class
* @since JDK1.0
*/
public class Object {
/**
* Returns the runtime class of an object. That Class
* object is the object that is locked by static synchronized
* methods of the represented class.
*
* @return the object of type Class that represents the
* runtime class of the object.
*/
public final Class getClass() {
return null;
}
/**
* Returns a hash code value for the object. This method is
* supported for the benefit of hashtables such as those provided by
* java.util.Hashtable.
*
* The general contract of hashCode is:
*
* - Whenever it is invoked on the same object more than once during
* an execution of a Java application, the hashCode method
* must consistently return the same integer, provided no information
* used in 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.
*
- If two objects are equal according to the equals(Object)
* method, then calling the
hashCode method on each of
* the two objects must produce the same integer result.
* - It is not required that if two objects are unequal
* according to the {@link java.lang.Object#equals(java.lang.Object)}
* method, then calling the 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 hashtables.
*
*
* As much as is reasonably practical, the hashCode method defined by
* class 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
* JavaTM programming language.)
*
* @return a hash code value for this object.
* @see java.lang.Object#equals(java.lang.Object)
* @see java.util.Hashtable
*/
public int hashCode() {
return 0;
}
/**
* Indicates whether some other object is "equal to" this one.
*
* The equals method implements an equivalence relation
* on non-null object references:
*
* - It is reflexive: for any non-null reference value
*
x, x.equals(x) should return
* true.
* - It is symmetric: for any non-null reference values
*
x and y, x.equals(y)
* should return true if and only if
* y.equals(x) returns true.
* - It is transitive: for any non-null reference values
*
x, y, and z, if
* x.equals(y) returns true and
* y.equals(z) returns true, then
* x.equals(z) should return true.
* - It is consistent: for any non-null reference values
*
x and y, multiple invocations of
* x.equals(y) consistently return true
* or consistently return false, provided no
* information used in equals comparisons on the
* objects is modified.
* - For any non-null reference value
x,
* x.equals(null) should return false.
*
*
* The equals method for class Object implements
* the most discriminating possible equivalence relation on objects;
* that is, for any non-null reference values x and
* y, this method returns true if and only
* if x and y refer to the same object
* (x == y has the value true).
*
* Note that it is generally necessary to override the hashCode
* method whenever this method is overridden, so as to maintain the
* general contract for the hashCode method, which states
* that equal objects must have equal hash codes.
*
* @param obj the reference object with which to compare.
* @return true if this object is the same as the obj
* argument; false otherwise.
* @see #hashCode()
* @see java.util.Hashtable
*/
public boolean equals(Object obj) {
return false;
}
/**
* 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 x, the expression:
*
*
* x.clone() != x
* will be true, and that the expression:
*
*
* x.clone().getClass() == x.getClass()
* will be true, but these are not absolute requirements.
* While it is typically the case that:
*
*
* x.clone().equals(x)
* will be true, this is not an absolute requirement.
*
* By convention, the returned object should be obtained by calling
* super.clone. If a class and all of its superclasses (except
* Object) obey this convention, it will be the case that
* x.clone().getClass() == x.getClass().
*
* 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 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 super.clone
* need to be modified.
*
* The method clone for class Object performs a
* specific cloning operation. First, if the class of this object does
* not implement the interface Cloneable, then a
* CloneNotSupportedException is thrown. Note that all arrays
* are considered to implement the interface Cloneable.
* 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.
*
* The class Object does not itself implement the interface
* Cloneable, so calling the clone method on an object
* whose class is 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 Cloneable interface. Subclasses
* that override the clone method can also
* throw this exception to indicate that an instance cannot
* be cloned.
* @see java.lang.Cloneable
*/
protected Object clone() throws CloneNotSupportedException {
return null;
}
/**
* Returns a string representation of the object. In general, the
* 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 toString method for class Object
* returns a string consisting of the name of the class of which the
* object is an instance, the at-sign character `@', 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:
*
*
* getClass().getName() + '@' + Integer.toHexString(hashCode())
*
*
* @return a string representation of the object.
*/
public String toString() {
return null;
}
/**
* 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 wait methods.
*
* 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.
*
* 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:
*
* - By executing a synchronized instance method of that object.
*
- By executing the body of a
synchronized statement
* that synchronizes on the object.
* - For objects of type
Class, by executing a
* synchronized static method of that class.
*
*
* 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 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
* wait methods.
*
* 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.
*
* This method should only be called by a thread that is the owner
* of this object's monitor. See the 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 void notifyAll() {}
/**
* Causes 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.
*
* The current thread must own this object's monitor.
*
* This method causes the current thread (call it T) to
* place itself in the wait set for this object and then to relinquish
* any and all synchronization claims on this object. Thread T
* becomes disabled for thread scheduling purposes and lies dormant
* until one of four things happens:
*
* - Some other thread invokes the notify method for this
* object and thread T happens to be arbitrarily chosen as
* the thread to be awakened.
*
- Some other thread invokes the notifyAll method for this
* object.
*
- Some other thread {@link java.lang.Thread#interrupt() interrupts}
* thread T.
*
- The specified amount of real time has elapsed, more or less. If
* timeout is zero, however, then real time is not taken into
* consideration and the thread simply waits until notified.
*
* The thread T 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 wait
* method was invoked. Thread T then returns from the
* invocation of the wait method. Thus, on return from the
* wait method, the synchronization state of the object and of
* thread T is exactly as it was when the wait method
* was invoked.
*
* If the current thread is
* {@link java.lang.Thread#interrupt() interrupted} by another thread
* while it is waiting, then an InterruptedException is thrown.
* This exception is not thrown until the lock status of this object has
* been restored as described above.
*
* Note that the 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.
*
* This method should only be called by a thread that is the owner
* of this object's monitor. See the 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 another thread has interrupted
* the current thread. The interrupted status 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(long timeout) throws InterruptedException {}
/**
* Causes 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.
*
* This method is similar to the 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:
*
*
* 1000000*timeout+nanos
*
* In all other respects, this method does the same thing as the
* method {@link #wait(long)} of one argument. In particular,
* wait(0, 0) means the same thing as wait(0).
*
* 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:
*
* - Another thread notifies threads waiting on this object's monitor
* to wake up either through a call to the
notify method
* or the notifyAll method.
* - The timeout period, specified by
timeout
* milliseconds plus nanos nanoseconds arguments, has
* elapsed.
*
*
* The thread then waits until it can re-obtain ownership of the
* monitor and resumes execution.
*
* This method should only be called by a thread that is the owner
* of this object's monitor. See the 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 another thread has interrupted
* the current thread. The interrupted status of the
* current thread is cleared when this exception is thrown.
*/
public final void wait(long timeout, int nanos) throws InterruptedException { }
/**
* Causes 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 wait(0).
*
* 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 notify method or the
* notifyAll method. The thread then waits until it can
* re-obtain ownership of the monitor and resumes execution.
*
* This method should only be called by a thread that is the owner
* of this object's monitor. See the 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 another thread has interrupted
* the current thread. The interrupted status 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 { }
/**
* 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 finalize method to dispose of
* system resources or to perform other cleanup.
*
* The general contract of finalize is that it is invoked
* if and when the JavaTM 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 finalize method may take any action, including
* making this object available again to other threads; the usual purpose
* of 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.
*
* The finalize method of class Object performs no
* special action; it simply returns normally. Subclasses of
* Object may override this definition.
*
* The Java programming language does not guarantee which thread will
* invoke the 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.
*
* After the 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.
*
* The finalize method is never invoked more than once by a Java
* virtual machine for any given object.
*
* Any exception thrown by the finalize method causes
* the finalization of this object to be halted, but is otherwise
* ignored.
*
* @throws Throwable the Exception raised by this method
*/
protected void finalize() throws Throwable { }
}