marking a field Serializable

[user1234]

Hi ,

I would like to know the intended behaviour when you mark a field with in a class of Type Serializable

eg private Serializable xyz

Though the class migth not implement Serializable.

[Tolls]

You're not marking it as Serializable.
You're saying attribute "xyz" is of a class that implements Serializable.

Which is pretty useless in most cases.

[user1234]

so suppose for a declaration

private Serializable parentId;

what would a parentId be of type and what would the potential values of parentid be of?
if parentId is of a class that implements Serializable then taht could be any class.

can you tell me where exactly and in what context can it be used.

[Tolls]

You don't use Serializable like that, unless you're doing something funky which someone other that me would have to explain.

You declare classes as Serializable, and define attributes as transient if you don't want them to be serialised.

Your "parentId" example would simply inform whatever system you have that parentId is Serializable. That's it.

[user1234]

Exactly its the first time I have seen it -
if thast what it tells the compiler then what use is it if teh class itself is not considered Serializable and what is the datatype of parentid in this case? that is confusing me

[Tolls]

Does the class do anything with it?
Not knowing what the situation is I really can't tell you what it's doing.

Where did you see this code?

[user1234]

no ther are just attributes defined as mentioned above - and then there are just constructers and setters and getters thats it . so a class dow not implement serializable but has these fields

[Tolls]

The only thing I can think of, without knowing anything else at all about what it is you're looking at (so this could well be wrong), is that the class is some sort of serliazing mechanism, which holds a bunch of Serializable things. Why? I can't say because I don't have the code.

You do...

[r035198x]

You are more likely to see it in conjunction with inheritance for framework code. e.g A database key is most useful if it is Serializable (and Comparable) so you could have

import java.io.Serializable;
public interface Entity<I extends Serializable & Comparable<I>> extends Serializable, Comparable<Entity<I>> {
	I getId();
}

[Tolls]

Does that match the description given so far though?

They're saying they have a class (unless I'm misreading this badly) that looks like (well, with getters and setters etc):

public class Something {
    Serializable someAttribute;
    Serializable anotherAttribute;
}

That doesn't seem to be to be quite the same beast.