java-design-patterns

Learn how to combine Observer and Mediator patterns in Java. Route subject notifications via a Mediator hub to coordinate Observers and eliminate direct dependencies in complex event systems.

**The Command Query Responsibility Segregation (CQRS) pattern splits application logic into two distinct layers: commands that mutate state within transactions, and queries that execute read-only operations returning lightweigh...

**The Unit of Work pattern groups multiple database operations into a single atomic transaction that executes only when you explicitly call `commit()`, ensuring data consistency by delaying persistence until all business rules ...

Learn to implement the Repository pattern in Java. Isolate domain logic from data access using a collection-like interface for CRUD operations with Spring Data JPA.

Learn how to implement the Dependency Injection pattern in Java to achieve loose coupling. Swap implementations easily without modifying existing code and improve maintainability.

Implement the Null Object Pattern in Java to eliminate null checks. Learn how to replace null references with stateless, do-nothing implementations for safer code.

Learn to implement the Template Method pattern in Java for algorithm frameworks. Define algorithm skeletons and reuse code effectively with this GoF design pattern.

Implement the Adapter pattern for legacy system integration in Java. Learn to create a wrapper class enabling seamless interoperability with legacy code without modification.

Learn to implement the Facade pattern in Java to simplify complex API interfaces. Encapsulate multistep operations behind intuitive methods for cleaner code.

Learn to implement the Iterator pattern in Java using generics for type-safe, reusable collection traversal without exposing internal structure. Master this essential design pattern.

Learn to implement the Memento pattern in Java for effortless state snapshot and restoration. Capture and restore object states without exposing internal details.

Learn how to implement the Flyweight pattern for memory-efficient object pools. Reduce memory consumption by sharing immutable objects and support massive object counts without heap growth.