InvalidClassException Exception in Java

java.lang.Object

            java.lang.Throwable

                        java.lang.Exception

                                    java.io.IOException

                                                java.io.ObjectStreamException

                                                            java.io.InvalidClassException

public class InvalidClassException extends ObjectStreamException

Throws when the Serialization runtime detects a problem with a Class:

1) The serial version of the class does not match that of the class descriptor read from the stream.

2) The class contains unknown datatypes.

3) The class does not have an accessible no-arg constructor.

4) The class is not public.

5) The class implements only one of writeObject or readObject methods.