In which cases is it advisable to use dependency injection through the constructor?

Dependency injection through the constructor is advisable when:

• Dependencies are essential for the correct operation of the object and must be provided at its creation.
• It is necessary to ensure the immutability of dependencies after the object is created.
• It is important to explicitly specify which components the class depends on, which improves readability and testability.
• There is a plan to use inversion of control (IoC) and dependency injection containers.

Example in Java:

public class Service {
    private final Repository repository;

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

    public void perform() {
        repository.save();
    }
}

Here, Repository is passed through the constructor, which makes it easy to replace the implementation during testing or when changing business logic.