This week's book giveaway is in the Agile and other Processes forum. We're giving away four copies of The Mikado Method and have Ola Ellnestam and Daniel Brolund on-line! See this thread for details.
Hi All,
Iam still not cleared with the purpose of Marker Interface inspite of reading many articles.I think one way communiction on this topic will not help me in understanding and so this thread.
Cloneable is a Marker Interface.
When we call clone() on an object - this will throw CloneNotSuppException if the class does not implement Cloneable interface.
So, I need to implement Cloneable - Whats the advantage/benefit/point here.Why not the developer just can call clone() irrespective of not implementing Cloneable interface???
Cloneable and clone() is a bit of a weird design (dating back to the earliest version of Java), so it's probably not a good example of how a marker interface should be used*. But it does demonstrate how they can be used.
A better example is RandomAccess. This is a marker interface used to indicate whether a List can support efficient random access. ArrayList implements RandomAccess, but LinkedList does not. The idea is that an algorithm using a list can check for this (using instanceof), and can use the best approach depending on whether random access is efficient or not.
(* Some would say that nowadays a marker interface should never be used, because annotations are a better solution. They weren't available in the earliest versions of Java).
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