/*
  Author:  James Tam
  Version: March 5, 2021

  Learning objective: types, casting, call overriden methods and
  methods unique to the child.

*/


public class Driver
{
   public static void main (String [] args)
   {
      X anX = new X ();
      anX.method1();

     Y anY = new Y ();
     anY.method1();
     anY.method2();

    // problem no such method in X: 
    // anX.method2();

    // problem: can't cast X to Y
    // ((Y) anX).method2();


    anX = anY;
    // Problem: anX is a reference to an X
    //anX.method2();

    // Works because anX now happens to refer to Y object, dangerous because it could also refer to an X object
    ((Y) anX).method2();

    // Safer: check for type before casting
    if (anX instanceof Y)
        ((Y) anX).method2();
   }
}