Abstract class in Java

Question

What is an \"abstract class\" in Java?

Answer 1

An abstract class is a class that is declared abstract — it may or may not include abstract methods. Abstract classes cannot be instantiated, but they can be subclassed.

In other words, a class that is declared with abstract keyword, is known as abstract class in java. It can have abstract(method without body) and non-abstract methods (method with body).

Important Note:- Abstract classes cannot be used to instantiate objects, they can be used to create object references, because Java's approach to run-time Polymorphism is implemented through the use of superclass references. Thus, it must be possible to create a reference to an abstract class so that it can be used to point to a subclass object. You will see this feature in the below example

abstract class Bike{  
  abstract void run();  
}  

class Honda4 extends Bike{  
    void run(){
        System.out.println("running safely..");
    }  

    public static void main(String args[]){  
       Bike obj = new Honda4();  
       obj.run();  
    }  
}