Possible Duplicates:
Do Hibernate table classes need to be Serializable?
What does Serializable mean?
public class ExampleEntity implements Serializable
{
@Id
private long id;
private int fieldInt;
private long fieldLong;
private String fieldString;
}
I am looking after JPA tutorials. I am able to understand the basic concepts, but in all the tutorials they have added, this serializable. What is the purpose of this? How does that help me? Any suggestions Please?
It means that the class can be serialized. This means that it can be converted into an stream of 0's and 1's and be sent to other service, like a webservice or and ORM (hibernate) or whatever. Then this service knows how store the stream.
Also, your program can receive a serialized class and create an instance for it from the stream of 0's and 1's.
It's the way to "save" instances of classes and "restore" them at any other moment in time.
More info at
To be able to make a class serializable, you must implement the interface "Serializable".
Why so? Because when the moment to serialize a class arrive, the function writeObtject will be called to convert the object into bytes. On the other hand, when you have the bytes and you want to get the instance of the class, the function readObject will be called.
Why is not automatic? A variable value it's already represented by bytes. Because the problem comes for example when a class holds instances of other classes. What do you do? You serialize the other classes as well? You just keep the reference address? It's pretty complex and it may be dependant on your type of project and design.
Serializable classes can be serialized - converted into bytes for storing on a hard drive or transmitting over a network.