In OOP, objects collaborate. The initial idea of collaboration, first found in Smalltalk, was for object A to send a message to object B. Languages designed later use method calling. In both cases, the same question stands: how does an object reference other objects to reach the desired results? In this post, I tackle the problem of passing dependencies to an object. I will go through several options and analyze their respective pros and cons.

Creational patterns were first described in the famous Gang of Four’s Design Patterns. The book presents each pattern in a dedicated chapter and follows a strict structure for each one: intent, motivation, applicability, structure, participants, collaborations, consequences, implementation, sample codes, known uses, and related patterns. The intent pattern presents a succinct goal of the pattern, while the applicability tells when you should use it.

Java is the first language I learned in my career. Its structure is foundational in my early years of understanding programming concepts. After going through several other languages with very different approaches, I’ve widened my point of view. Today, I want to reflect on the idea of inheritance. Inheritance in Java In Java, the idea of inheritance is tightly coupled with the concept of subtyping. Subtyping is the implementation of a IS A relationship.

This week, during a workshop related to a Java course I give at a higher education school, I noticed the code produced by the students was mostly - ok, entirely, procedural. In fact, though the Java language touts itself as an Object-Oriented language, it’s not uncommon to find such code developed by professional developers in enterprises. For example, the JavaBean specification is in direct contradiction of one of OOP’s main principle, encapsulation.