The Factory Method Design Pattern is a creational pattern that defines an interface for creating an object but lets subclasses alter the type of objects that will be created. Instead of calling a constructor directly, the client calls a factory method, promoting loose coupling between client code and the concrete classes it uses. This pattern provides flexibility and scalability for object creation.
- Bakery Making Cakes: A bakery can make different types of cakes (chocolate, vanilla, fruit) based on the customer's order, using a method that selects the cake type at runtime.
- Car Rental Service: A car rental agency can provide different types of vehicles (SUV, sedan, truck) depending on the customer’s needs, not always the same model.
- Animal Breeding Farms: A breeding farm might produce different types of animals (horses, cows, sheep) based on demand or season.
- Furniture Factory: A furniture factory produces chairs, tables, or sofas. Each product creation follows a basic procedure but results in different final items.
- UI Frameworks: Toolkits like Java Swing or Android UI use factory methods to create various UI components like buttons, text fields, and windows without coupling to specific subclasses.
- Logger Systems: Logging libraries often use factory methods to create loggers configured for different outputs (console, file, network) without requiring the client to know about the specific implementation.
- Database Connections: Systems may use factory methods to return different types of database connections (MySQL, Oracle, PostgreSQL) based on configuration without changing client code.
- Provides Extension Points: Subclasses can override the factory method to determine the specific type of object to instantiate.
- Reduces Tight Coupling: Client code depends only on abstract products and creators, promoting flexibility and maintainability.
- Single Responsibility Principle: Separates object creation code from business logic, making code cleaner and easier to modify.
- Can Be Combined with Other Patterns: Often used alongside patterns like Singleton (for factory instance) or Template Method (for creation steps).