Abstract

 package com.company;

/*Abstract class ke help se aur dusri class banegi standard abstract class have no object
 for abstract class extend the other class should have extract or the override the abstract
 _ when an abstract class is sub classed ,the subclass usually implementations for all of the methods in parent class.If doesn't it must be declared abstract

 */
 abstract class Parent{
     public Parent(){
         System.out.println("Mai base2 ka constructor hoon ");
     }
     public void sayhello(){
         System.out.println("Hello");
     }
    abstract public void greet();
    abstract public void greet2();
}
class child2 extends Parent{
     @Override
    public void greet(){
              System.out.println("Good morning ");
     }
     @Override
    public void greet2(){
             System.out.println("Good Evening ");
}}

abstract class child3 extends Parent{
     public void th(){
         System.out.println("I am good ");
     }
}
public class Abstract {
    public static void main(String[] args) {
//        Parent p=new parent();   It is the abstract class  ----error
   child2 c=new child2();
    c.greet();
    c.greet2();
//        child3 c=new child3();   It is the abstract class  ----error
    }
}

//o\p

Mai base2 ka constructor hoon 
Good morning 
Good Evening