Why is it important to use dependency injections in development?

Dependency Injection (DI) is important because it:

• Increases modularity and testability of the code. Components do not create their dependencies themselves but receive them from outside, which simplifies replacing and mocking dependencies during testing.

• Reduces coupling between classes. Classes depend on abstractions (interfaces) rather than concrete implementations, making the code easier to maintain and extend.

• Facilitates configuration and management of dependencies. Especially in large applications, frameworks (like Spring) can centrally manage the creation and lifecycle of objects.

Example of constructor injection:

public class Service {
    private final Repository repository;

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

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

Here, Service does not create Repository itself but receives it from outside, which simplifies replacing the implementation.