ObjectStreamClass (Java SE 26 & JDK 26)
Description: declaration: module: java.base, package: java.io, class: ObjectStreamClass
Keywords: java.io.ObjectStreamClass class

# 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()`
  Creates and returns a copy of this object.
  `boolean`
  `equals(Object obj)`
  Indicates whether some other object is "equal to" this one.
  `protected void`
  `finalize()`
  Deprecated, for removal: This API element is subject to removal in a future version.
  Finalization is deprecated and subject to removal in a future release.
  `final Class<?>`
  `getClass()`
  Returns the runtime class of this `Object`.
  `int`
  `hashCode()`
  Returns a hash code value for this object.
  `final void`
  `notify()`
  Wakes up a single thread that is waiting on this object's monitor.
  `final void`
  `notifyAll()`
  Wakes up all threads that are waiting on this object's monitor.
  `final void`
  `wait()`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
  `final void`
  `wait(long timeoutMillis)`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
  `final void`
  `wait(long timeoutMillis, int nanos)`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

- ## 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:
      a string representation of the object