How to distinguish the principle of dependency injection in Spring from the D principle of the SOLID responsibility separation?

The principle of dependency injection (DI) in Spring is a way of managing object dependencies by externally providing the required components, rather than creating them inside the class. This makes the code more flexible and testable, as dependencies can be easily replaced.

The Single Responsibility Principle (SRP) from SOLID states that a class should have only one reason to change, meaning it should be responsible for a single specific task or functionality. This improves code readability and maintainability.

In other words, DI is a pattern for managing dependencies between objects, while SRP is a design principle aimed at properly distributing responsibilities among classes.

Example of DI in Spring:

@Component
public class Service {
    private final Repository repository;

    @Autowired
    public Service(Repository repository) {
        this.repository = repository;
    }
}

Here, Service does not create the Repository itself but receives it from outside, which corresponds to DI.

SRP, on the other hand, requires that Service only handles business logic, and Repository handles data access.