What is similarities between interface and classes?

Answer 1

The similarities are:

a. They are both java basic object types

b. They both can contain variables and methods (With difference being class methods have implementation code whereas the interface methods can only have declarations)

c. They can both be inherited using Inheritance (extends keyword for classes and implements keyword for interfaces)

Answer 2

Classes and Interfaces are both Java files. They are saved as .java files with the name as the public class or public interface name.

The difference is that, classes are fully coded. That is, they have all the necessary variables and methods coded in them. But in case of Interfaces, only methods are declared. They are not defined. Interfaces are only like skeletons whereas classes can implement interfaces and complete the skeleton.

Answer 3

The similarities are:

a. They can both be used for inheritance

b. They can both have methods (Of course interfaces can have only method declarations whereas classes can also have code inside methods)

c. They can both have variables (We can declare the access modifier class variables but for interfaces they are by default public, static and final)

d. A class can be instantiated but an interface cannot.