|CONTENTS | PREV | NEXT||Java Object Serialization Specification
May 12, 2005 Updates for JavaTM SE Development Kit, v6 Beta 1
- Added statement about how an array object returned by a
readResolveinvocation for an unshared read is handled.
- Clarified the behavior in the event of an invalid
- Clarified that
serialVersionUIDmatching is waived for array classes.
- Clarified when
IllegalArgumentExceptionis thrown by
July 24, 2003 Updates for JavaTM 2 SDK, Standard Edition, v1.5 Beta 1
- Added support for serializing enum constants.
- Added specification of class modifier flags used in the computation of default
serialVersionUIDvalues to Section 4.6, "Stream Unique Identifiers".
Aug. 16, 2001 Updates for JavaTM 2 SDK, Standard Edition, v1.4 Beta 2
- Added support for class-defined
readObjectNoDatamethods, to be used for initializing serializable class fields in cases not covered by class-defined readObject methods. See Section 3.5, "The readObjectNoData Method", as well as Appendix A, "Security in Object Serialization".
- New methods
ObjectInputStream.readUnsharedprovide a mechanism for ensuring unique references to deserialized objects. See Section 2.1, "The ObjectOutputStream Class", Section 3.1, "The ObjectInputStream Class", as well as Appendix A, "Security in Object Serialization".
- Documented new security checks in the one-argument constructors for
ObjectInputStream. See Section 2.1, "The ObjectOutputStream Class" and Section 3.1, "The ObjectInputStream Class".
- Added caution against using inner classes for serialization in Section 1.10, "The Serializable Interface".
- Clarified requirement that class-defined
writeFieldsonce before writing optional data, and that class-defined
readFieldsonce before reading optional data. See Section 2.3, "The writeObject Method" and Section 3.4, "The readObject Method".
- Clarified the behavior of
readExternalmethods attempt read operations which exceed the bounds of available data; see Section 3.4, "The readObject Method" and Section 3.6, "The readExternal Method".
- Clarified the description of non-proxy class descriptor field type strings to require that they be written in "field descriptor" format; see Section 6.2, "Stream Elements".
July 30, 1999 Updates for JavaTM 2 SDK, Standard Edition, v1.3 Beta
- Added the ability to write
Stringobjects for which the UTF encoding is longer than 65535 bytes in length. See Section 6.2, "Stream Elements".
- New methods
ObjectInputStream.readClassDescriptorprovide a means of customizing the serialized representation of
ObjectStreamClassclass descriptors. See Section 2.1, "The ObjectOutputStream Class" and Section 3.1, "The ObjectInputStream Class".
- Expanded Appendix A, "Security in Object Serialization".
Sept. 30, 1998 Updates for JDKTM 1.2 Beta4 RC1
June 22, 1998 Updates for JDKTM 1.2 Beta4
- Eliminated JDKTM 1.2
Resolvable.References to either of these classes as an interface should be replaced with
java.io.Serializable. Serialization will use reflection to invoke the methods,
readResolve, if the Serializable class defines these methods. See Section 2.5, "The writeReplace Method" and Section 3.7, "The readResolve Method."
- New javadoc tags @serial, @serialField, and @serialData provide a way to document the Serialized Form of a Serializable class. Javadoc generates a serialization specification based on the contents of these tags. See Section 1.6, "Documenting Serializable Fields and Data for a Class."
- Special Serializable class member,
serialPersistentFields, must be declared private. See Section 1.5, "Defining Serializable Fields for a Class."
- Clarified the steps involved in computing the
serialVersionUIDin Section 4.6, "Stream Unique Identifiers."
Feb. 6, 1998 Updates for JDKTM 1.2 Beta 3
- Introduced the concept of STREAM_PROTOCOL versions. Added the
STREAM_PROTOCOL_2version to indicate a new format for
Externalizableobjects that enable skipping by an
Externalizableobject within the stream, even when the object's class is not available in the local Virtual Machine. Compatibility issues are discussed in Section 6.3, "Stream Protocol Versions."
The ObjectInputStream.resolveClassmethod can return a local class in a different package than the name of the class within the stream. This capability enables renaming of packages between releases. The
serialVersionUIDand the base class name must be the same in the stream and in the local version of the class. See Section 3.1, "The ObjectInputStream Class."
- Allow substitution of
arrayobjects when writing them to or reading them from the stream. See Section 2.1, "The ObjectOutputStream Class" and Section 3.1, "The ObjectInputStream Class."
Sept. 4, 1997 Updates for JDKTM 1.2 Beta1
- Separated the Replaceable interface into two interfaces: Replaceable and Resolvable. The Replaceable interface allows a class to nominate its own replacement just before serializing the object to the stream. The Resolvable interface allows a class to nominate its own replacement when reading an object from the stream.
- Modified serialization to use the JDKTM 1.2 security model. There is a check for
SerializablePermission "enableSubstitution"within the
ObjectOutputStream.enableResolvemethods. See Section 2.1, "The ObjectOutputStream Class" and Section 3.1, "The ObjectInputStream Class."
writeObject's exception handler to write handled
IOExceptions into the stream. See Section 2.1, "The ObjectOutputStream Class."
July 3, 1997 Updates for JDKTM 1.2 Alpha
- Documented the requirements for specifying the serialized state of classes. See Section 1.5, "Defining Serializable Fields for a Class."
- Added the Serializable Fields API to allow classes more flexibility in accessing the serialized fields of a class. The stream protocol is unchanged. See Section 1.7, "Accessing Serializable Fields of a Class," Section 2.2, "The ObjectOutputStream.PutField Class," and Section 3.2, "The ObjectInputStream.GetField Class."
- Clarified that field descriptors and data are written to and read from the stream in canonical order. See Section 4.1, "The ObjectStreamClass Class."