What are the main differences between Dependency Injection and Factory Design Pattern, and in which scenarios would you choose one over the other in a Spring application?

Main Differences Between Dependency Injection and Factory Design Pattern in Spring

Dependency Injection:

• Dependency Injection is a design pattern where components are provided with their dependencies rather than creating them internally.
• In Spring, Dependency Injection is achieved through IoC (Inversion of Control) container that manages the dependencies of different components.
• It promotes loose coupling between components, making them easier to test, maintain, and extend.

Factory Design Pattern:

• Factory Design Pattern is a creational design pattern that provides an interface for creating objects without specifying the exact class of object that will be created.
• In Spring, Factory Design Pattern can be implemented using factory beans that create and return instances of classes based on certain conditions or configurations.
• It allows for centralizing the logic of object creation and decoupling the client code from the actual object instantiation process.

Scenarios for Choosing Between Dependency Injection and Factory Design Pattern in a Spring Application

Choose Dependency Injection when:

• You want to achieve better manageability of dependencies between components.
• You prefer a more declarative and configuration-based approach for wiring components.
• You require easier testability and flexibility in changing dependencies at runtime.

Choose Factory Design Pattern when:

• You need more control over the object creation process based on runtime conditions.
• You want to encapsulate complex instantiation logic and provide a clear separation of concerns.
• You have varying object creation requirements that cannot be handled solely through Dependency Injection.

Overall, the choice between Dependency Injection and Factory Design Pattern in a Spring application depends on the specific requirements and design considerations of the project. Both patterns have their strengths and can be used effectively in different scenarios to enhance the overall architecture and maintainability of the application.