Dependency Injection vs Factory Pattern

In coding, there are special ways to organize our work called “design patterns.” Two important ones are Dependency Injection (DI) and the Factory Pattern. They help make our work easier by keeping things neat and separate. In this article, we will see the differences between them and, when to use each.

The Dependency Injection (DI) pattern is a design pattern used in software engineering to manage dependencies between objects. In DI, instead of a class creating its dependencies internally, these dependencies are provided to the class from an external source. This allows for greater flexibility, easier testing, and improved maintainability of the codebase.

• Flexibility: Classes become more flexible as they can easily switch between different implementations of dependencies.
• Testability: Dependency Injection facilitates easier unit testing, as dependencies can be easily replaced with mock objects.
• Maintainability: Code becomes easier to maintain and extend, as changes to dependencies can be made externally without modifying the class itself.

The Factory Method Design Pattern is a creational design pattern used in software engineering to provide an interface for creating objects in a superclass, while allowing subclasses to alter the type of objects that will be created.

• It encapsulates the object creation logic in a separate method, abstracting the instantiation process and promoting loose coupling between the creator and the created objects.
• This pattern enables flexibility, extensibility, and maintainability in the codebase by allowing subclasses to define their own implementation of the factory method to create specific types of objects.

Below are the differences between Dependency Injection Pattern and Factory Pattern:

Below are the use cases of Dependency Injection Pattern:

• Modular Application Design:
  • Dependency Injection is commonly used in modular application design, where classes and components are designed to be loosely coupled.
  • By injecting dependencies externally, classes become more modular and easier to maintain, test, and extend.
• Unit Testing:
  • DI facilitates easier unit testing by allowing dependencies to be replaced with mock objects or stubs during testing.
  • This enables developers to isolate and test individual components of the system without having to instantiate complex dependencies.
• Integration with Frameworks:
  • Dependency Injection is widely used in frameworks and libraries, such as Spring Framework (Java) and Angular (JavaScript), for managing object dependencies and configuring application components.

Below are the use cases of Factory Pattern:

• Encapsulation of Object Creation Logic:
  • Factory Pattern is commonly used to encapsulate object creation logic within factory classes, abstracting away the details of object instantiation from client code.
  • This promotes encapsulation and abstraction, making client code cleaner and more maintainable.
• Variability in Object Creation:
  • Factory Pattern is suitable for scenarios where object creation logic needs to be varied based on runtime conditions or configuration parameters.
  • For example, a factory class may dynamically create different types of database connections based on user preferences or environment settings.
• Dynamic Selection of Object Implementation:
  • Factory Pattern allows for the dynamic selection of object implementations based on runtime conditions.
  • This flexibility is useful in scenarios where multiple implementations of an interface or abstract class exist, and the appropriate implementation needs to be selected at runtime.

Dependency Injection and the Factory Pattern are both helpful ways to organize our work and make it easier to do. Dependency Injection helps us bring in parts from outside, while the Factory Pattern helps us make things without worrying about how they’re made. By understanding these patterns, we can write work that’s easier to understand, check, and change.