Question

My serializable class is not getting read in with objectinputstream after adding static methods to the class, is this expected behavior? Where in the javadoc does it state adding static methods to a serializable class creates incompatibility?

Answer 1

In the Java Object Serialization Specification, section 4.6:

The stream-unique identifier is a 64-bit hash of the class name, interface class names, methods, and fields.

…

For each non-private method sorted by method name and signature:

• The name of the method.
• The modifiers of the method written as a 32-bit integer.
• The descriptor of the method.

No, I can’t work out how it could actually break compatibility of serialized state either, but this is why it’s either worth avoiding the default Java binary serialization (e.g. for Protocol Buffers) or always declaring a serialVersionUid yourself.