serialization/deserialization mechanism

Question

Say, I have a class X which has a field value, that is,

class X implements Serializable {
    private i         


        

Answer 1

The real details can be read in the Java Object Serialization Specification.

To answer your questions:

1. Serialization has a basic sanity check to see if the serialization ends use the same version of a class: the serialVersionUID member must be equal. Read the section Stream Unique Identifiers to know more about it. Basically, it's a static value which you can either manage yourself by declaring it on your class, or let the compiler generate one for you. If the compiler generates it, ANY change to a class will result in a change of serialVersionUID and hence will make the deserialization fail if the ends do not have exactly the same classes. If you want to avoid this, declare the variable yourself and update it manually when a change to the class' member variables does make classes incompatible.

2. The Java Virtual Machine does a lot of the magic here, it can access all internal state directly without the need for getters (fields marked transient or static aren't serialized though). Also, while the Serializable interface doesn't specify any methods to implement, there are a number of 'magic methods' which you can declare to influence the serialization process. Read section "The writeObject Method" and onwards to know more. Be aware though that you should use these sparingly as they might confuse any maintenance developers!