Lombok & Spring framework

Lombok is a widely used Java library to eliminate boilerplate code for setters, getters, Equals & Hashcode etc. The focus of this article is go over some of the Lombok annotations when used with SpringBoot framework.

Constructor Injection: Spring allows injecting mandatory dependencies via constructor which is the most preferred way. Let’s look at Listing 1 below, that declares a Spring service class that has 2 dependencies via dependency1, dependency2 both injected via constructor.

Listing 1:

@Service
class Service {
   private Dependency1 dependency1;
   private Dependency2 dependency2;
   
   @Autowired 
   public class Service(Dependency1 dependency1, Dependency1 dependency2) {
       this.dependency1 = dependency1;
       this.dependency2 = dependency2;
  }
}

Let’s see how Listing 1 can be updated to use Lombok annotations in Listing 2. It uses @RequiredAllArgsConstructor annotation which signals that all the instance variables are final and initialized through constructor, when this annotation is used in conjunction with @Service Spring will inject them through the constructor.

Listing 2:

@Service
@RequiredAllArgsConstructor
class Service {
   private final Dependency1 dependency1;
   private final Dependency1 dependency2;
}