Serialization

The classes you need to understand are all in the java.io package; they include: ObjectOutputStream and ObjectInputStream primarily, and FileOutputStream and FileInputStream because you will use them to create the low-level streams that the ObjectXxxStream classes will use.
* A class must implement the Serializable interface before its objects can be
serialized.
* The ObjectOutputStream.writeObject() method serializes objects, and the ObjectInputStream.readObject() method deserializes objects.
* If you mark an instance variable transient, it will not be serialized even thought the rest of the object's state will be.
* You can supplement a class's automatic serialization process by implementing the writeObject() and readObject() methods. If you do this, embedding calls to defaultWriteObject() and defaultReadObject(), respectively, will handle the part of serialization that happens normally.
* If a superclass implements Serializable, then its subclasses do automatically.
* If a superclass doesn't implement Serializable, then when a subclass object is deserialized, the superclass constructor will run.