3 Object Oriented Design Principles

• Write code that declares, implements and/or extends interfaces
• Choose between interface inheritance and class inheritance
• Apply cohesion, low-coupling, IS-A, and HAS-A principles
• Apply object composition principles (including has-a relationships)
• Design a class using a Singleton design pattern
• Write code to implement the Data Access Object (DAO) pattern
• Design and create objects using a factory pattern