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 ...

Twenty-three years ago, in his Design Principles and Design Patterns article, Robert "Uncle Bob" Martin boiled down the Liskov substitution principle to the idea that "derived classes should be ...

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 ActionListener ...