Dynamic polymorphism

Casting always perfomred if there is inheritance

• parent-child relation
• Casting not related to run time

Abstract Classes and Interfaces

Abstract class can be used to create child class

• Only in inheritance

Abstrct class must have atleast one abstract method

• In abstract classs we can create the constrctor.
• This abstract class's constructor get called whenever we call their child classes.

package com;

abstract class Engine{

    public Engine(){
        System.out.println("Constructor class..");
    }

    public abstract void fType();

    }



class Car extends Engine{

    @Override
    public void fType() {
        System.out.println("CNG");

    }

}

class Bus extends Engine{

    @Override
    public void fType() {
        System.out.println("Diesel");
    }

}

class AP extends Engine{

    @Override
    public void fType() {
        System.out.println("Aero");
    }

}

public class AbstractDemo {

    public static void main(String[] args) {
        Engine e = new Car();
        e.fType();

        e = new Bus();
        e.fType();

        e=new AP();
        e.fType();

    }

}

Abstrct class can have both abstract method and non abstract method

• Abstract method is mandatory to override.

Abstract method can not be created outside of abstract class

Declare any class with even one method as abstract as abstract Cannot be instantiated Cannot use Abstract modifier for: ▪ Constructors ▪ Static methods Abstract class’ subclasses should implement all methods or declare themselves as abstract Can have concrete methods also

Java doesn't allow multiple inheritance

• Because of the confusion

ANonymous classes