扩展实现Serializable的类

Question

If I extend a class that implements Serializable, do I need that class to also implement Serializable?

For instance if I have,

public class classToBeExtended implements Serializable

Then will this suffice?

public class classThatWillExtend extends classToExtended

Or do I need to do this?

public class classThatWillExtend extends classToExtended implements Serializable

Answer 1

Per Javadoc :

All subtypes of a serializable class are themselves serializable

Answer 2

If any of a class's superclasses implements a given interface, then the subclass also implements that interface. Serializable is not special in that regard, so no, the subclasses of a Serializable class do not need to explicitly declare that they implement Serializable . They can so declare, but doing that makes no difference.

The other implication is that if you extend a Serializable class, you should ensure that the subclass is indeed serializable itself. For example, don't add non- transient fields of non-serializable types unless you're prepared also to add the necessary methods to support them.