An abstract class is not an interface. It is a base class that can be extended by another class. As such it can be instantiated indirectly. Interfaces cannot.
Saying that "interface is nothing but a pure abstract class" is not correct. Though they may seem similar, they are not the same. A class can extend only one abstract base class, but can implement any number of interfaces.
You seem to see a connection between having a constructor and being a class file; that connection is spurious at best - better not to get attached to it.
when a class is compiled , it is converted into executable byte code , which is the .class file, on the other hand constructors are used to create instances i.e objects of a class
Post by:autobot
Sasparilla and fresh horses for all my men! You will see to it, won't you tiny ad?
a bit of art, as a gift, the permaculture playing cards