HFOOAD Chapter 5 Interlude

1. HFOOAD Chapter 5 Interlude OO Catastrophe!

3. Two possible answers Interface Abstract class Defines behavior Can have implementation code Cannot be instantiated A class can inherit from a single abstract class Unless the language supports multiple inheritance • Defines behavior • Contract • Cannot be instantiated • A class can implement multiple interfaces • In languages that support interfaces

4. How do I know when to use an interface and when to use an abstract class? If (almost) all classes implementing the behavior would have the same code, then you can use an abstract class to implement it. Avoid repeating code with abstract classes Program to interfaces

6. ENCAPSULATION Isn’t encapsulation just about hiding implementation?

7. Solution 1

8. Solution 2

9. Prefer delegation over inheritance

11. Manage change Manage change Manage change … Change Change Change Change

12. Final Catastrophe challenge

13. Our solution