Get started modeling entities and relationships for Java data persistence ... and how objects relate. Two examples are encapsulation and inheritance: Association, aggregation, composition ...

Although Java prevents a developer from extending more than one class, a simple trick ... that the message server example could have been completed without multiple inheritance.

This example will show you four different ways to implement this functional interface in your code — starting with how to use an actual class, and how to create very concise code with a lambda ...