How Serialization Detects When a Class Has Changed ?

Posted in: Java Serialization

In order for serialization to gracefully detect when a versioning problem has occurred, it needs to be able to detect when a class has changed. As with all the other aspects of serialization, there is a default way that serialization does this. And there is a way for you to override the default.

The default involves a hashcode. Serialization creates a single hashcode, of type long, from the following information:

• The class name and modifiers
• The names of any interfaces the class implements
• Descriptions of all methods and constructors except private methods and constructors
• Descriptions of all fields except private, static, and private transient