Casting in Java

Follwing Blog is about Upcasting and Downcasting In Java.
Upcasting
Upacsting Is a concept used to support Runtime Polymorphism in which Parent Class refernce variable can hold child value
Syntax

A ob=new B(); // Memory of B is allocated to Object of A

It is to be Noted that Upcasting Never Fails. When we are upcasting we can use only method or function which is a part of parent but called through child object.
Downcasting
Downcasting is also a way to casting reference of Child Class to one of its Parent Class

B ob=(A)x;  // Instance of A is allocated to B Object

It Is to be noted that Downcasting may Fails.

Following Program helps you to clear all doubts u are having...

public class A {
    public void Show()
    {
        System.out.println("Calling from A's Show()");
    }

}
public class B {
    public void Show()
    {
        System.out.println("Calling from B's Show()");
    }
    public void Display()
    {
        System.out.println("Calling from B's display()");
    }

}
public class Demo {
    public static void main(String ar[])
    {
        A x=new B(); // Upcasting
        x.show();
        B y=(B)x; // Downcasting
        y.Display();
    }
}