generic types

[Owen O'Malley]

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