Why do most system architects insist on first programming to an interface?

Question

Almost every Java book I read talks about using the interface as a way to share state and behaviour between objects that when first \"constructed\" did not seem to share a r

Answer 1

You could see this from a perl/python/ruby perspective :

• when you pass an object as a parameter to a method you don't pass it's type , you just know that it must respond to some methods

I think considering java interfaces as an analogy to that would best explain this . You don't really pass a type , you just pass something that responds to a method ( a trait , if you will ).