Tom and Dick are neighbors. Dick makes a lot of noise on Sunday mornings, which drives Tom crazy. Communication has become difficult between them because of this.

If Tom and Dick cannot talk to each other directly, Dick will continue to make noise and Tom will get angry every Sunday.

When communication is difficult between two objects or in a system (here the neighborhood), the solution is delegation to a third-party object. This object will make communication easier between all other objects.

This is exactly the solution proposed by the Mediator pattern. To implement this pattern, we need:

• An abstract representation of a neighbor (abstract class should be preferred because it centralizes the reference to the mediator)
• An abstract representation of a neighborhood mediator (abstract class or interface)
• Concrete neighbors (Tom and Dick)
• A concrete mediator (Harry)