Programming Language Concepts
			  Jan-Apr 2009
			  Assignment 1

		  Due Monday, 16 February, 2009

1. Define an abstract class Shape with concrete subclasses
   Circle, Square, Rectangle such that every class that inherits
   from Shape MUST redefine the following methods:

   a. "public double sizeOf()" that returns some sensible
      parameter indicating the size of the object.

   b. "public boolean equals(Object o)" based on the defining
      characteristics of the object rather than on pointer equality.

   c. "public String toString()" to print out the defining
      characteristics of the object.

2. Consider the following interface:

   public interface Sortable
   {
     public int cmp(Sortable s);  
     // return -1 if this < s, 0 if this = s, 1 if this > s
   }   

   a. Write a method that sorts arrays of type Sortable (use any
      sorting algorithm of your choice).

   b. Extend the definition of Shape so that all objects that
      inherit from Shape are Sortable, and update the definitions of
      Circle, Square and Rectangle accordingly.

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