Lecture 9: Object Oriented Design: Interfaces and Abstract Classes

lecture audio (thought I was recording video in higher quality…instead, just didn’t record video)

Textbook section

2.3

Interfaces

In general:

• We don’t need to know what’s going on underneath the hood! We just need the interface to be specified.

In Java:

• An interface is a collection of method declarations with no data and no bodies.
• Interfaces have no constructors and they cannot be directly instantiated.
• A class then implements an interface.

Abstract classes

• In between an interface and a normal (concrete) class
• Example: we can implement Animal as an abstract class, while Tortoise, Otter, and SlowLoris inherit from and implement its abstract methods.

Files used in class

• Sellable.java
• Photograph.java
• Animal.java
• Otter.java

Additional exercises