title: If my class implements Serializable, do I have to implement it in its subclasses?
body: <p>If I have B extends A... and A implements Serializable, do I have to write "B implements Serializable" ?</p>
  
  <p>I think no, but I would like confirmation...</p>
  
  <p>also if I put serialization id in A... do I need to put one in B also ? should serialization id in A be protected (not private) ?</p>