Behavioral Design Patterns

Behavioral patterns define how objects interact and distribute responsibilities. They establish communication protocols, delegate work, and coordinate object behavior—addressing the "what" and "how" of object interaction rather than object structure.

Pattern Family Overview

Behavioral Patterns Classification

Categories at a Glance

Chain & Delegation

Distribute responsibility across a chain of handlers or through a mediator coordinating multiple objects.

Command & Execution

Encapsulate actions as objects and manage their execution, undo, and sequencing.

Iteration & Traversal

Define ways to access elements sequentially or traverse complex structures without exposing their implementation.

Observation & Notification

Establish loose coupling through subscriptions, state capture, and event propagation.

State & Behavior

Vary object behavior based on internal state or external strategy without conditional logic.

Specification & Query

Encapsulate business rules and selection criteria as queryable objects.

📄️ Chain of Responsibility Pattern

Pass requests along a chain of handlers, each deciding to process or forward the request

📄️ Command Pattern

Encapsulate a request as an object allowing you to parameterize clients with commands

📄️ Interpreter Pattern

Define a grammar and interpreter for a language to process structured text or commands

📄️ Iterator Pattern

Access elements of a collection sequentially without exposing its underlying representation

📄️ Mediator Pattern

Centralize complex communication logic between multiple objects in a mediator object

📄️ Memento Pattern

Capture and externalize an object's state without violating encapsulation

📄️ Observer / Pub-Sub Pattern

Define a one-to-many dependency where when one object changes state, all dependents are notified

📄️ State Pattern

Allow an object to alter its behavior when its internal state changes

📄️ Strategy Pattern

Define a family of algorithms, encapsulate each, and make them interchangeable

📄️ Template Method Pattern

Define the skeleton of an algorithm, deferring specific steps to subclasses

📄️ Visitor Pattern

Represent an operation to be performed on elements of an object structure

📄️ Null Object Pattern

Provide an object as surrogate for null reference with neutral behavior

📄️ Specification Pattern

Encapsulate business rules as queryable objects for flexible filtering and validation