// abstract class

abstract class Main {

  public String fname = "John";

  public int age = 24;

  public abstract void study(); // abstract method 

}

​

// Subclass (inherit from Main)

class Student extends Main {

  public int graduationYear = 2018;

  public void study() { // the body of the abstract method is provided here

    System.out.println("Studying all day long");

  }

}