CODEWITHSUNDEEP
javainheritance
AnkitChhajed
AnkitChhajed

Reputation: 415

Can I access a subclass method through a base class-typed reference?

Below is the piece of code I am trying to work on but unable to sort out the issue: "Can I really do the below in Java.. If yes please help to know me "How" and if no "Why?" "... Have a look at the code below...

class Base{

      public void func(){

            System.out.println("In Base Class func method !!");         
      };
}

class Derived extends Base{

      public void func(){   // Method Overriding

            System.out.println("In Derived Class func method"); 
      }

      public void func2(){  // How to access this by Base class reference

            System.out.println("In Derived Class func2 method");
      }  
}

class InheritDemo{

      public static void main(String [] args){

            Base B= new Derived();
            B.func2();   // <--- Can I access this ??? This is the issue...
      }
}

Thanks in advance!!!! Waiting for some helpful answers :) ...

Upvotes: 1

Views: 9875

Answers (5)

David Kroukamp
David Kroukamp

Reputation: 36423

short and sweet? No you cant.. How must Base know what functions/methods are present in the extended class?

EDIT:

By explict/type casting, this may be achieved, as the compiler takes it you know what you are doing when casting the object Base to Derived:

if (B instanceof Derived) {//make sure it is an instance of the child class before casting
((Derived) B).func2();
}

Upvotes: 4

Razvan
Razvan

Reputation: 10093

Since the type of object B is Base and the Base type doesn't have a func2() in its public interface, your code is not going to compile.

You can either define B as Derived or cast the B object to Derived: 

   Derived B = new Derived(); B.func2();
   //or
   Base B = new Derived(); ((Derived)B).func2();

Upvotes: 2

Gilbert Le Blanc
Gilbert Le Blanc

Reputation: 51445

Like this:

((Derived) B).func2();

Upvotes: 0

Peter Lawrey
Peter Lawrey

Reputation: 533500

You can do

((Derived) B).func2();

You can't do

B.func2();

as func2 is not a method of the Base class.

Upvotes: 1

srikanth yaradla
srikanth yaradla

Reputation: 1235

This wont even compile as B is unaware of the func2

Upvotes: 2

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