Polymorphism

Polymorphism is a concept made possible by inheritance in which a name denotes instances of many different classes, as long as they are related by a common super-class.

 

Example: public void paint() {         Iterator it = shapes.iterator();         while (it.hasNext()) {           // polymorphism: shape can refer to squares,           //circles, triangles, etc.         Shape shape = (Shape)shapes.next();         shape.draw(); } }

 

Example: Polymorphism solving design problem (encapsulation violation)

BAD: (a) Bad use of Constraint - an Account can have either Person OR Corporation associated with it. Violates encapsulation

GOOD: (b) Use polymorphism via inheritance to represent the disjunction.