java.util.Pair

[tom.hawtin at oracle.com]

On 30/03/2010 09:08, Weijun Wang wrote:

 > I know such a simple thing can be made very complex and everyone might
 > want to add a new method into it. How about we just make it most
 > primitive? Simply an immutable and Serializable class, two final
 > fields, one constructor, two getters (?), and no static factory
 > methods.

Even with the diamond operator, I'd prefer a static creation method to a 
constructor. Immutable value classes really should not have 
constructors. I'd also like to support Comparable for Comparables.

 >          (S)he who does the real implementation has the privilege to
 > choose between head/tail and car/cdr.

Or are you suggesting an abstract base class to support two-field 
immutables? IMO, a good idea from a strong-typing perspective, but lazy 
programmers will probably want a concrete pair or they'll keep 
implementing their own.

Tom