Java in a Nutshell, 5th Edition [Electronic resources]

Signals that an object cannot be serialized. It is thrown when serialization is attempted on an instance of a class that does not implement the Serializable interface. Note that it is also thrown when an attempt is made to serialize a Serializable object that refers to (or contains) an object that is not Serializable. A subclass of a class that is Serializable can prevent itself from being serialized by throwing this exception from its writeObject( ) and/or readObject( ) methods.

public class 
NotSerializableException  extends ObjectStreamException {
// Public Constructors
public 
NotSerializableException ( );  
public 
NotSerializableException (String 
classname );  
}