Effective Java

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ITEM 86: IMPLEMENT SERIALIZABLE WITH GREAT CAUTION
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Classes designed for inheritance that do implement 
Serializable
include
Throwable
and 
Component
. 
Throwable
implements 
Serializable
so RMI can
send exceptions from server to client. 
Component
implements 
Serializable
so
GUIs can be sent, saved, and restored, but even in the heyday of Swing and AWT,
this facility was little-used in practice.
If you implement a class with instance fields that is both serializable and
extendable, there are several risks to be aware of. If there are any invariants on the
instance field values, it is critical to prevent subclasses from overriding the
finalize
method, which the class can do by overriding 
finalize
and declaring it
final. Otherwise, the class will be susceptible to 
finalizer attacks (
Item 8). Finally,
if the class has invariants that would be violated if its instance fields were
initialized to their default values (zero for integral types, 
false
for 
boolean
, and
null
for object reference types), you must add this 
readObjectNoData
method: