Serializable a object properties too
-
13-07-2021 - |
Question
When I have Serializable
in a class, do I need to add Serializable
to all my objects within the class?
For example,
public class User implements Serializable{
private List<Role> role;
private Task task;
}
Do I need to add Serializable
to Role
and Task
, too?
public class Task implements Serializable{
// ...
}
public class Role implements Serializable{
// ...
}
Solution
Yes, you do; if your classes Task
and Role
are not Serializable
, you'll get a java.io.NotSerializableException
if you try to serialize an instance of User
.
Ofcourse, if Task
or Role
contain other non-primitive, non-transient fields, they would have to be Serializable
too, etc.
OTHER TIPS
That is the simplest option.
The other option is to make those fields tranisent and "override" writeObject and readObject to implement your own serialization for those classes. It is unlikely this is worth the extra effort.
BTW: If you have a nested class, the outer class needs to be Serializable as well as the nested class implicitly has a reference to it even if you don't use it. For this reason and others I suggest making nested classes static
whenever possible.
Short answer: yes. Each object wihtin your serializable class MUST be serializable by itself. Otherwise all properties can't be restored or whatever.
Furthermore, you will also get an exception when trying to serialize this object.
From doc
Classes that do not implement this interface will not have any of their state serialized or deserialized.
So yes.
Serializable Yes because :
Classes that do not implement this interface will not have any of their state
serialized or deserialized. All subtypes of a serializable class are themselves
serializable. The serialization interface has no methods or fields and serves
only to identify the semantics of being serializable.
If you try to serialize an object of a class which implements Serializable, but the object includes a reference to an non- Serializable class then a NotSerializableException
will be thrown at runtime