|
|||||||||
Home >> All >> ClassLib >> Common >> java >> [ lang overview ] | PREV CLASS NEXT CLASS | ||||||||
SUMMARY: ![]() ![]() ![]() |
DETAIL: FIELD | CONSTR | METHOD |
ClassLib.Common.java.lang
Class Object

java.lang.ObjectClassLib.Common.java.lang.Object
- public abstract class Object
- extends java.lang.Object
Object
- Version:
- $Id: Object.java,v 1.8 2003/05/12 10:04:53 joewhaley Exp $
Constructor Summary | |
Object()
|
Method Summary | |
java.lang.Class |
_getClass()
|
void |
_notify()
|
void |
_notifyAll()
|
void |
_wait(long timeout)
|
protected java.lang.Object |
clone()
This method may be called to create a new copy of the Object. |
int |
hashCode()
Get a value that represents this Object, as uniquely as possible within the confines of an int. |
private static void |
registerNatives()
|
Methods inherited from class java.lang.Object |
equals, finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
Object
public Object()
Method Detail |
registerNatives
private static void registerNatives()
_getClass
public final java.lang.Class _getClass()
hashCode
public int hashCode()
- Description copied from class:
java.lang.Object
- Get a value that represents this Object, as uniquely as
possible within the confines of an int.
There are some requirements on this method which subclasses must follow:
- Semantic equality implies identical hashcodes. In other
words, if
a.equals(b)
is true, thena.hashCode() == b.hashCode()
must be as well. However, the reverse is not necessarily true, and two objects may have the same hashcode without being equal. - It must be consistent. Whichever value o.hashCode() returns on the first invocation must be the value returned on all later invocations as long as the object exists. Notice, however, that the result of hashCode may change between separate executions of a Virtual Machine, because it is not invoked on the same object.
Notice that since
hashCode
is used in java.util.Hashtable and other hashing classes, a poor implementation will degrade the performance of hashing (so don't blindly implement it as returning a constant!). Also, if calculating the hash is time-consuming, a class may consider caching the results.The default implementation returns
System.identityHashCode(this)
- Semantic equality implies identical hashcodes. In other
words, if
clone
protected java.lang.Object clone() throws java.lang.CloneNotSupportedException
- Description copied from class:
java.lang.Object
- This method may be called to create a new copy of the
Object. The typical behavior is as follows:
o == o.clone()
is falseo.getClass() == o.clone().getClass()
is trueo.equals(o)
is true
However, these are not strict requirements, and may be violated if necessary. Of the three requirements, the last is the most commonly violated, particularly if the subclass does not override Object.equals(Object)>
Object.equals(Object)
55 .If the Object you call clone() on does not implement java.lang.Cloneable (which is a placeholder interface), then a CloneNotSupportedException is thrown. Notice that Object does not implement Cloneable; this method exists as a convenience for subclasses that do.
Object's implementation of clone allocates space for the new Object using the correct class, without calling any constructors, and then fills in all of the new field values with the old field values. Thus, it is a shallow copy. However, subclasses are permitted to make a deep copy.
All array types implement Cloneable, and override this method as follows (it should never fail):
public Object clone() { try { super.clone(); } catch (CloneNotSupportedException e) { throw new InternalError(e.getMessage()); } }
_notify
public final void _notify()
_notifyAll
public final void _notifyAll()
_wait
public final void _wait(long timeout) throws java.lang.InterruptedException
|
|||||||||
Home >> All >> ClassLib >> Common >> java >> [ lang overview ] | PREV CLASS NEXT CLASS | ||||||||
SUMMARY: ![]() ![]() ![]() |
DETAIL: FIELD | CONSTR | METHOD |