why serializable interface called as marker interface

[kesava chaitanya]

hi

when a class implements the interface we will override those methods in the class;But in the case of serializable interface we wont implement(readObject and writeObejct) methods in the particulr class.why?
[ November 08, 2004: Message edited by: kesava chaitanya ]

[Mike Gershman]

Many serializable objects can use the default versions of readObject() and writeObject() contained in ObjectInputStream and ObjectOutputStream respectively. Only if the default versions can't handle a class does that class have to supply specialized versions of readObject() and writeObject()

Putting these methods in the Serializable interface would not allow any serializable classes to use the default methods.