Java in a Nutshell, 5th Edition

Name

ObjectInputStream.GetField

Synopsis

This class holds the values of named fields read by an ObjectInputStream. It gives the programmer precise control over the deserialization process and is typically used when implementing an object with a set of fields that do not match the set of fields (and the serialization stream format) of the original implementation of the object. This class allows the implementation of a class to change without breaking serialization compatibility.

In order to use the GetField class, your class must implement a private readObject( ) method that is responsible for custom deserialization. Typically, when using the GetField class, you have also specified an array of ObjectStreamField objects as the value of a private static field named serialPersistentFields. This array specifies the names and types of all fields expected to be found when reading from a serialization stream. If there is no serialPersistentField field, the array of ObjectStreamField objects is created from the actual fields (excluding static and transient fields) of the class.

Within the readObject( ) method of your class, call the readFields( ) method of ObjectInputStream( ). This method reads the values of all fields from the stream and stores them in an ObjectInputStream.GetField object that it returns. This GetField object is essentially a mapping from field names to field values, and you can extract the values of whatever fields you need in order to restore the proper state of the ...