why cant subclass objects hold super class constructor

Question

Can anybody explain me what is the reason for a sub class object is incapable of holding a super class constructor?

class Alpha 
{
   String getType1() 
   {
      return "alpha";
    }
}

class Beta extends Alpha 
{
   String getType1() 
   {
      return "beta";
   }
   String acc()
   {
      return "acc"; 
   }
}

public static void main(String[] args)
{
   Alpha a1=new Beta();
   System.out.println(a1.getType1());
 }

Here the output is "beta"; but object a1 doesnt have the visibility to acc()?

Answer 1

Nothing surprising here:

System.out.println(a1.getType1());

You are calling a method that is defined in the super class; and overridden in the a subclass. You create an instance of the subclass; and the method that gets executed ... is the overridden version.

The fact that Beta contains another method which is not at all used in your example anyway doesn't come into play here at all. And even if getType1() would be calling acc() - that would still work. That is the essence of of polymorphism!

And just to be precise: none of the methods you have in your classes is a constructor!