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 Serializable 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 be invoked, along with its superconstructor(s).
• DataInputStream and DataOutputStream aren't actually on the exam, in spite of what the Sun objectives say.