Introduction to Design Patterns
Learn what design patterns are, the Gang of Four (GoF), the three categories of patterns (Creational, Structural, Behavioral), and why every Java developer should know them.
Singleton Pattern
Learn the Singleton design pattern in Java — how to ensure only one instance of a class exists using private constructors, thread-safe double-checked locking, and the best-practice Enum singleton.
Factory Pattern
Learn the Factory Method and Abstract Factory design patterns in Java — how to create objects without specifying the exact class, with a Shape factory and notification factory example.
Builder Pattern
Learn the Builder design pattern in Java — constructing complex objects step by step using an inner static Builder class, with optional fields, method chaining, and a mention of Lombok @Builder.