Java™ How To Program (Early Objects), Tenth Edition

1.5.9 Interfaces

Java also supports interfaces—collections of related methods that typically enable you to tell objects what to do, but not how to do it (we’ll see an exception to this in Java SE 8). In the car analogy, a “basic-driving-capabilities” interface consisting of a steering wheel, an accelerator pedal and a brake pedal would enable a driver to tell the car what to do. Once you know how to use this interface for turning, accelerating and braking, you can drive many types of cars, even though manufacturers may implement these systems differently.

A class implements zero or more interfaces, each of which can have one or more methods, just as a car implements separate interfaces for basic driving functions, controlling the radio, controlling ...