Class ObjectStreamClass

java.lang.Object

java.io.ObjectStreamClass

All Implemented Interfaces:

Serializable

public final class ObjectStreamClass
extends Object
implements Serializable

Serialization's descriptor for classes. It contains the name and serialVersionUID of the class. The ObjectStreamClass for a specific class loaded in this Java VM can be found/created using the lookup method.

The algorithm to compute the SerialVersionUID is described in Java Object Serialization Specification, Section 4.6, "Stream Unique Identifiers".

Since:

1.1

External Specifications

• Java Object Serialization Specification

See Also:

• ObjectStreamField
• Java Object Serialization Specification, Section 4, "Class Descriptors"
• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final ObjectStreamField[]	NO_FIELDS	serialPersistentFields value indicating no serializable fields

Method Summary

Modifier and Type	Method	Description
Class<?>	forClass()	Return the class in the local VM that this version is mapped to.
ObjectStreamField	getField(String name)	Get the field of this class by name.
ObjectStreamField[]	getFields()	Return an array of the fields of this serializable class.
String	getName()	Returns the name of the class described by this descriptor.
long	getSerialVersionUID()	Return the serialVersionUID for this class.
static ObjectStreamClass	lookup(Class<?> cl)	Find the descriptor for a class that can be serialized.
static ObjectStreamClass	lookupAny(Class<?> cl)	Returns the descriptor for any class, regardless of whether it implements Serializable.
String	toString()	Return a string describing this ObjectStreamClass.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Field Details

NO_FIELDS

public static final ObjectStreamField[] NO_FIELDS

serialPersistentFields value indicating no serializable fields

Method Details

lookup

public static ObjectStreamClass lookup(Class<?> cl)

Find the descriptor for a class that can be serialized. Creates an ObjectStreamClass instance if one does not exist yet for class. Null is returned if the specified class does not implement java.io.Serializable or java.io.Externalizable.

Parameters:

cl - class for which to get the descriptor

Returns:

the class descriptor for the specified class

lookupAny

public static ObjectStreamClass lookupAny(Class<?> cl)

Returns the descriptor for any class, regardless of whether it implements Serializable.

Parameters:

cl - class for which to get the descriptor

Returns:

the class descriptor for the specified class

Since:

1.6

getName

public String getName()

Returns the name of the class described by this descriptor. This method returns the name of the class in the format that is used by the Class.getName() method.

Returns:

a string representing the name of the class

getSerialVersionUID

public long getSerialVersionUID()

Return the serialVersionUID for this class. The serialVersionUID defines a set of classes all with the same name that have evolved from a common root class and agree to be serialized and deserialized using a common format. NonSerializable classes have a serialVersionUID of 0L.

Returns:

the SUID of the class described by this descriptor

forClass

public Class<?> forClass()

Return the class in the local VM that this version is mapped to. Null is returned if there is no corresponding local class.

Returns:

the Class instance that this descriptor represents

getFields

public ObjectStreamField[] getFields()

Return an array of the fields of this serializable class.

Returns:

an array containing an element for each persistent field of this class. Returns an array of length zero if there are no fields.

Since:

1.2

getField

public ObjectStreamField getField(String name)

Get the field of this class by name.

Parameters:

name - the name of the data field to look for

Returns:

The ObjectStreamField object of the named field or null if there is no such named field.

toString

public String toString()

Return a string describing this ObjectStreamClass.

Overrides:

toString in class Object

Returns:

String a printable representation for the receiver.