UpCasting DownCasting

[Thirukumaran Gopalakrishnan]

Upcasting DownCasting example please.

[Paul Anilprem]

http://www.codeguru.com/java/tij/tij0070.shtml

[Louis Moloney]

example:

ArrayList a = new ArrayList();

Collection c = a; // upcast implicit no need for (ArrayList)a

ArrayList b = (ArrayList)c; // downcast requires explicit cast

upcast dont require an explicit cast as a subclass is always guaranteed to pass the is-a test with its parent. ie ArrayList is a Collection.

downcast requires an explicit cast because the object being cast might not be what its being cast to. You are basically saying to the compiler trust me i know what im doing.