Serialisation

Question 1

What is Serialization

Answer 1

1.state of an object -> byte stream
2. can be saved to:
DB
Disk
Transferred over network

Question 2

What is Deserialization

Answer 2

byte stream -> java object in memory

Question 3

‘static’ member

Answer 3

No

1. Static variables belong to a class and not to any individual instance.
2. The concept of serialization is concerned with the object’s current state. Only data associated with a specific instance of a class is serialized,
3. therefore static member fields are ignored during serialization

Question 4

‘transient’ member

Answer 4

serialization - > The value will be ignored

Deserialization -> value is null(default value)

Question 5

‘final’ + ‘transient’ member

Answer 5

serialization - > The value will NOT be ignored

Deserialization -> value exists

Question 6

serialVersionUID

Answer 6

1. private static final long serialVersionUID = 1L;
2. InvalidClassException - If there is a difference between serialVersionUID of loaded receiver class and corresponding sender class then InvalidClassException will be thrown
3. no serialVersionUID field defined explicitly - serialization runtime will calculate default value for that class. Which can vary based on compiler implementation

Question 7

Why Java serialisation is bad performance

Answer 7

implements Serializable:

1. Expend object size
2. using reflection very slow
3. create a lot of temp obj/gabbage

Best practice/alternatives?
Protobuf

Question 8

What kind of exception will be thrown if some field is not serializable? How to handle it?

Answer 8

TO_DO