Interface Class

Actually Interface are just like a class where it consists only constants and they
We can extend interface via interfaces
We can implement the interface via classes.
In interface needn’t use the “public” or “abstract” keywords – all methods
declared by an interface are automatically public and abstract by default.
A simple example of interface implement is given below.
public interface [...]

Static method

public class Student {
private static int totalStudents;
// Other details omitted.
// Constructor.
public Student() {
// Details omitted.
// Automatically increment the student count every time we
// instantiate a new Student.
totalStudents++;

}

Polymorphism on three classes

This Polymorphism is one of the special feature of OOPL(Object oriented Programming Language). The polymorphism can perform several functions with a  single method. A simple example of Polymorphism is given below according to real world.
The term polymorphism refers to the ability of two or more objects belonging to different classes to respond to [...]