Java Spring Quick Tip — Episode 1

1. Use constructor injection instead of @Autowire

• Constructor injection

@Component
@RequiredArgsConstructor
public class TraceFacade {

    private final TraceService traceService;

    public void createTrace(TraceCreateRequest traceCreateRequest) {
        traceService.createTrace(TraceMapper.INSTANCE.map(traceCreateRequest));
    }

}

• @Autowired injection

@Component
public class TraceFacade {

    @Autowired
    private TraceService traceService;

    public void createTrace(TraceCreateRequest traceCreateRequest) {
        traceService.createTrace(TraceMapper.INSTANCE.map(traceCreateRequest));
    }
}

Constructor injection involves passing dependencies as constructor parameters, while @Autowired is a type of field injection that automatically sets the value of a field by matching it to a bean of the same type in the Spring container.

Here are some key differences between the two:

1. Explicitness: Constructor injection is more explicit because the dependencies are passed as constructor parameters, making it clear what dependencies are required by the class. In contrast, field injection using @Autowired is less explicit because the dependencies are set by Spring behind the scenes.
2. Testability: Constructor…