The Observable design pattern is used in many important Java APIs. One well-known example is a JButton that uses the ActionListener API to execute an action. In this example, we have an ...

In Part 2, I’ll present a helpful way to learn the foundational design patterns presented by the Gang of Four authors, revisit the book’s Visitor pattern from a Java technology perspective ...

Object-oriented systems are usually partitioned into layers of related responsibilities and only dependencies in one direction are allowed, from higher layers (more specific, less reusable) to lower ...