Overridding Pls Explain this code

[Ganesh Kannusamy]

class Super
{ int index = 5;
public void printVal()
{ System.out.println( "Super" );
}
}
class Sub extends Super
{ int index = 2;
public void printVal()
{ System.out.println( "Sub" );
}
}
public class Runner
{ public static void main( String argv[] )
{ Super sup = new Sub();
System.out.print( sup.index + "," );
sup.printVal();
}
}

ANS: (5, sub)

Iam clear about "sub" as ouput, but not clear how "5" comes as output

Thanks for your reply,
Ganesh

[Keith Lynn]

You are creating a Sub object but referring to it with a Super reference.

Instance variables are not overridden, they are hidden.

When an instance variable in a subclass has the same name as an instance variable in a superclass, then the instance variable is chosen in the class that is the reference type.

[Siri Naray]

then how do we access the instance variable of a sub class with th esuper class ref variable. Is it not possible?

[Pinkal Patel]

No you can not Directly Used Sub class Instance variable throw the Super class variable.

[S Thiyanesh]

Only overridden instance methods are bind to run time polymorphism.
Others instance variables, static variables, static overridden (hidden) methods, and overloaded methods are all binded at compile time depending on the type of the reference variable and not on the object.

[Finner Jones]

then how do we access the instance variable of a sub class with th esuper class ref variable. Is it not possible?

You can use getter / setter access methods and override them in the subclasses.

class Super {
  int index = 5;
  
  public void printVal() {
  System.out.println("Super");
  }
  
  /*   access method to return index for this class  */
  public int getIndex() {
  return index;
  }
  
  
}
 
class Sub1 extends Super {
  int index = 2;
  
  public void printVal() {
  System.out.println("Sub");
  }
  
  /* overridden access method to return index for this class  */
  [B]public int getIndex()[/B] {
  return index;
  }
}
 

public class Runner {
public static void main(String [] args) {
Super sup = new Sub1();
Sub1 sub = new Sub1();

System.out.println([B]sup.getIndex()[/B] + ",");
sup.printVal();

}
}
 

The output is
2,
Sub


Finner