The serialization is actually implemented in
java.io.ObjectOutputStream (and java.io.ObjectInputStream) and some of its helper classes. In many cases, this built-in support is sufficient, and the developer simply needs to implement the marker interface
Serializable. This interface is called a "marker" because it doesn't declare any methods, and thus doesn't require any special API on implementation classes.
A programmer can add or replace default serialization mechanism with their own methods if needed. For example, if some additional initialization is required after deserializing an object, a method can be added with the following signature:
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, java.lang.ClassNotFoundException
For total control over serialization and deserialization, implement
java.io.Externalizable instead of
There are many other extension points in Java serialization, if needed. The serialization specification is an authoritative and complete source for learning about all of them.