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From Owen O'Malley <o...@yahoo-inc.com>
Subject generic types
Date Fri, 03 Nov 2006 15:52:15 GMT
Hi all,
   I've noticed a couple of people over-specifying the generic  
collections. The general pattern is:

Map<Key,Value> myMap = new HashMap();

where the field is given a type of the general interface with the  
type parameters and the constructor is the specific implementation  
without the type parameters. The assignment works because in Java  
(unlike C++) every T1<T2> extends T1.  The advantage of the general  
interface (eg. "Map" instead of "HashMap") is that if you change the  
implementation later, you only need to change the constructor.

Thanks,
    Owen

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