Abstract class and interface

Question

as I understood abstract classes are used as a template for the subclass, while an interface is a template for the methods of the subclass,

now what are they? just templates and if so, what they can be really be used for?
it's it will be better to see normal classes or even private ones and inherent from them to the subclass?

Answer 1

The difference between abstract class and interface that interface is a pure 100 % template but abstract class is 0 to 100% template (up to you).before java 8, interface is purely template.