Reputation: 89

Is serializable inheritable

Is serializable inheritable. Particulary if I have

class A implements Serializable{}

class B extends A{}

Is class B serializable?

Upvotes: 3

Answers (8)

Chris Gerken

Reputation: 16392

I agree that Serializable-ness is inherited, but have had problems (albeit rarely) where that fact is not recognized by the occasional tool. So even though it's not required, I will make the extra effort to also declare the subclass as implementing Serializable.

Upvotes: 0

user207421

Reputation: 310893

All interfaces implemented by base classes are inherited by their derived classes. Not just Serializable.

Upvotes: 0

Juned Ahsan

Reputation: 68715

Yes. This follows from the concept of inheritance in Java. Since A is serializable and B extends A, B is serializalbe.

Note that all non-static non-transient fields of A and B must also contain Serializable objects, otherwise there will be a NotSerializableException at runtime when you try to serialize them.

Upvotes: 2

Nikhil Agrawal

Reputation: 26528

If a class is Serializable then all subclasses are Serializable. But if you want to prevent sub class whose superclass is Serializable to be serializable it is also possible.

If you want to prevent then use

NotSerializableException -- Thrown when an instance is required to have a Serializable interface. The serialization runtime or the class of the instance can throw this exception. The argument should be the name of the class.

Refer official docs -- http://docs.oracle.com/javase/6/docs/api/java/io/NotSerializableException.html

By using it in this way you can accomplish this task

private void writeObject(ObjectOutputStream out) throws IOException {

    throw new NotSerializableException(“Not today!”);
}


private void readObject(ObjectInputStream in ) throws IOException {

    throw new NotSerializableException(“Not today!”);

}

How about sub class is serialized But parent class is not

If a Sub class is Serializable, it absolutely does not mean that its super class is also Serializable. When a subclass is de - serialized, the no-argument Constructor of the super class will run.

Upvotes: 0

ajduke

Reputation: 5057

Did the following check on given code

boolean b = new B() instanceof Serializable;
System.out.println(b);

which returns true

Upvotes: 2

0x90

Reputation: 40982

oracle tutorial:

Interfaces have another very important role in the Java programming language. Interfaces are not part of the class hierarchy, although they work in combination with classes. The Java programming language does not permit multiple inheritance (inheritance is discussed later in this lesson), but interfaces provide an alternative.

In Java, a class can inherit from only one class but it can implement more than one interface. Therefore, objects can have multiple types: the type of their own class and the types of all the interfaces that they implement. This means that if a variable is declared to be the type of an interface, its value can reference any object that is instantiated from any class that implements the interface. This is discussed later in this lesson, in the section titled "Using an Interface as a Type."

I guess what you mean Is if you have a function foo which gets (Serializable ptr), can you call it with an instance of Class B so the answer is yes, that is the Idea.

moreover you can Override the the A (ancestor) implementation.

Upvotes: 0