java.lang
Class Object

java.lang.Object

public class Object

The root of the Class hierarchy. Every Class in the system has Object as its ultimate parent. Every variable and method defined here is available in every Object.

See Also:
Class

Constructor Summary
Object()
           
 
Method Summary
protected  Object clone()
          Creates a clone of the object.
 boolean equals(Object obj)
          Compares two Objects for equality.
protected  void finalize()
          Code to perform when this object is garbage collected.
 Class getClass()
          Returns the Class of this Object.
 int hashCode()
          Returns a hashcode for this Object.
 void notify()
          Notifies a single waiting thread on a change in condition of another thread.
 void notifyAll()
          Notifies all of the threads waiting for a condition to change.
 String toString()
          Returns a String that represents the value of this Object.
 void wait()
          Causes a thread to wait forever until it is notified.
 void wait(long timeout)
          Causes a thread to wait until it is notified or the specified timeout expires.
 void wait(long timeout, int nanos)
          More accurate wait.
 

Constructor Detail

Object

public Object()
Method Detail

getClass

public final Class getClass()
Returns the Class of this Object. Java has a runtime representation for classes- a descriptor of type Class- which the method getClass() returns for any Object.


hashCode

public int hashCode()
Returns a hashcode for this Object. Each Object in the Java system has a hashcode. The hashcode is a number that is usually different for different Objects. It is used when storing Objects in hashtables. Note: hashcodes can be negative as well as positive.

See Also:
Hashtable

equals

public boolean equals(Object obj)
Compares two Objects for equality. Returns a boolean that indicates whether this Object is equivalent to the specified Object. This method is used when an Object is stored in a hashtable.

Parameters:
obj - the Object to compare with
Returns:
true if these Objects are equal; false otherwise.
See Also:
Hashtable

clone

protected Object clone()
                throws CloneNotSupportedException
Creates a clone of the object. A new instance is allocated and a bitwise clone of the current object is place in the new object.

Returns:
a clone of this Object.
Throws:
OutOfMemoryError - If there is not enough memory.
CloneNotSupportedException - Object explicitly does not want to be cloned, or it does not support the Cloneable interface.

toString

public String toString()
Returns a String that represents the value of this Object. It is recommended that all subclasses override this method.


notify

public final void notify()
Notifies a single waiting thread on a change in condition of another thread. The thread effecting the change notifies the waiting thread using notify(). Threads that want to wait for a condition to change before proceeding can call wait().

The method notify() can only be called by the thread that is the owner of the current object's monitor.

Throws:
IllegalMonitorStateException - If the current thread is not the owner of the Object's monitor.
See Also:
wait(long), notifyAll()

notifyAll

public final void notifyAll()
Notifies all of the threads waiting for a condition to change. Threads that are waiting are generally waiting for another thread to change some condition. Thus, the thread effecting a change that more than one thread is waiting for notifies all the waiting threads using the method notifyAll(). Threads that want to wait for a condition to change before proceeding can call wait().

The method notifyAll() can only be called by the thread that is the owner of the current object's monitor.

Throws:
IllegalMonitorStateException - If the current thread is not the owner of the Object's monitor.
See Also:
wait(long), notify()

wait

public final void wait(long timeout)
                throws InterruptedException
Causes a thread to wait until it is notified or the specified timeout expires.

The method wait() can only be called from within a synchronized method.

Parameters:
timeout - the maximum time to wait in milliseconds
Throws:
IllegalMonitorStateException - If the current thread is not the owner of the Object's monitor.
InterruptedException - Another thread has interrupted this thread.

wait

public final void wait(long timeout,
                       int nanos)
                throws InterruptedException
More accurate wait. The method wait() can only be called by the thread that is the owner of the current object's monitor.

Parameters:
timeout - the maximum time to wait in milliseconds
Throws:
IllegalMonitorStateException - If the current thread is not the owner of the Object's monitor.
InterruptedException - Another thread has interrupted this thread.

wait

public final void wait()
                throws InterruptedException
Causes a thread to wait forever until it is notified.

The method wait() can only be called from within a synchronized method

Throws:
IllegalMonitorStateException - If the current thread is not the owner of the Object's monitor.
InterruptedException - Another thread has interrupted this thread.

finalize

protected void finalize()
                 throws Throwable
Code to perform when this object is garbage collected. The default is that nothing needs to be performed. Any exception thrown by a finalize method causes the finalization to halt. But otherwise, it is ignored.

Throwable