11 Using Interfaces
After reading lesson 11, you will be able to:
- Understand the definition of an interface
- Create new interfaces
- Implement an interface
This lesson introduces the topic of interfaces in Java. An interface is considered a reference type in Java and serves several purposes. It acts as a rule or contract for any code that implements the interface. All functionality identified in the interface must be implemented. The interface contains a collection of abstract methods, constants, default methods, and static methods. Interfaces are used for dependency injection, unit testing and play a key role in design patterns.