A serializable class that is a subclass of a non-serializable class cannot be deserialized if its superclass does not declare a no-argument constructor. The Java serialization framework uses the no-argument constructor when it initializes the object instance that is created during deserialization. Deserialization fails with an InvalidClassException if its superclass does not declare a no-argument constructor.

The Java Development Kit API documentation states:

To allow subtypes of non-serializable classes to be serialized, the subtype may assume responsibility for saving and restoring the state of the supertype's public, protected, and (if accessible) package fields. The subtype may assume this responsibility only if the class it extends has an accessible no-arg constructor to initialize the class's state. It is an error to declare a class Serializable if this is not the case. The error will be detected at runtime.