Method calling using polymorphism

[Rahul Zanwar]

class Parent
{
    private display()
    {
        System.out.println("this is parent class method");
    }
}


class Child
{
  
}


class Test
{
    public static void main(String[] args) 
    {
       Parent p = new Child();
       p.display()
    }

}

======================================================


the above code works properly. I have one query, according to the law of polymorphism, the method calling should be:
when a parent class reference holds instance of child class, the child class method will be called.
But here the child class do not have the method "display", as it is declared private in parent class.
If this is working, then what is the rational behind this.?

[Henry Wong]

Rahul Zanwar wrote:
the above code works properly....
If this is working, then what is the rational behind this.?

The code, as you have shown, should *not* compile.

Henry

[Ganish Patil]

Welcome to CodeRanch!  

Rahul Zanwar wrote:the above code works properly

Are you sure? because void of display method of Parent is missing.

according to the law of polymorphism, the method calling should be:
when a parent class reference holds instance of child class, the child class method will be called.

Only if the parent class's method is overridden in the child class.

Here in your code, Child class doesn't extend Parent class

class Child // Here should be extends Parent
{
   
}

If this is working, then what is the rational behind this.?

This will not work because, below code

Parent p = new Child();

give compile time error Type mismatch: cannot convert from Child to Parent, because Child is not sub class of Parent. and

p.display()// ; is missing

although you add ; it gives compile time error which says The method display() from the type Parent is not visible, because it has private access modifier which means that method can only be accessed within Parent class but here you are trying to access it in Test class which is invalid. So this will not work.