I have encountered this code when reading a chapter about inheritance and
polymorphism. I was just trying to understand the concept of downcasting as
shown in code line 11 and the application of it. When would I need to cast
the super class reference (pointRef) and assign it back to a sub-class
reference (circleRef).

1   public static void main( String args[] )
2  {
3    Point pointRef, p;
4    Circle circleRef, c;
5
7
6      p = new Point( 30, 50 );
7      c = new Circle( 2.7, 120, 89 );
8
9     pointRef = c;
10
11     circleRef = (Circle) pointRef;
12
13 }

Thanks for your time.

NA Jam

if (o instanceof String)
  int length = ((String)o).length();
else
  throw new Exception("Not a String!);