Private final vs autowired

private final vs autowired

When it comes to dependency injection in Java, there are two commonly-used annotations: private final and @Autowired. Let’s take a closer look at each of them and their implications.

private final:

When you declare a dependency as private final, you are indicating that it is an immutable dependency that cannot be changed once it is set.

Here’s an example:

// Service class
public class MyService {
    private final MyDependency dependency;
    
    public MyService(MyDependency dependency) {
        this.dependency = dependency;
    }
    
    // Other methods and functionality
}

In this example, MyService has a dependency on MyDependency. By making the dependency field private final and initializing it in the constructor, we ensure that it cannot be modified once it is set.

The main advantage of using private final is that it enforces immutability and makes your code more robust and less prone to errors. It also promotes better design by clearly specifying dependencies that are required for the class to function correctly.

@Autowired:

@Autowired is an annotation provided by the Spring Framework that automatically injects dependencies into your classes.

Here’s an example:

// Service class
public class MyService {
    @Autowired
    private MyDependency dependency;
    
    // Other methods and functionality
}

In this example, @Autowired is used to automatically inject an instance of MyDependency into the dependency field of MyService.

The main advantage of using @Autowired is the convenience it provides. Spring takes care of managing and injecting the dependencies, allowing you to focus on the business logic without worrying about instantiation and wiring.

However, it’s important to note that using @Autowired can make your code less explicit about its dependencies and more tightly coupled to Spring. This can make unit testing more difficult and may lead to potential issues if the dependencies change in the future.

Conclusion:

Both private final and @Autowired are valid approaches for dependency injection in Java/Spring. The choice between them depends on your specific requirements and design preferences. private final offers more control and immutability, while @Autowired provides convenience and reduces boilerplate code.