Title: Key Concept - Interface
Course: CPS 189: Java Certification - Review, Practice & Prepare (Development) > Section: (OLDstyle) Learning Modules

An interface

- It is a set of constants and methods that may be implemented in another class.
- An interface constant is declared public, static, and final.
- It is a contract with any class that implements it in that the class must reference and define the implementation of every interface method.
- It contains the keyword interface in its declaration.

Interface methods may be one of the following:

- Abstract – the method is declared without an implementation.
- Default – the method contains the keyword default in its declaration and is implemented.
- Static method – the method contains the keyword static in its declaration and is implemented.

For more information about Defining an Interface:

Click this link to view Oracles's documentation: Defining an Interface