@PostConstruct: Nested dependency is null

Question

Here, all the dependencies in JobRepository are autowired correctly. But in the init() method, when jobUtil.findRootCarrier() is called, carrierService inside JobUtil seems to be null and its causing NPE.

@Component
@Transactional(Transactional.TxType.REQUIRES_NEW)
public class JobRepository {

    @Autowired
    public JobUtil jobUtil;

    @Autowired
    public JobsInitializer jobsInitializer;

    @PostConstruct
    public void init() {
        Form form = getBatchJobsForm();
        .........
    }

    private synchronized Form getBatchJobsForm() {
         Carrier carrier = jobUtil.findRootCarrier();
         .........
    }

}


@Component
public class JobUtil {

        @Autowired
        public CarrierService carrierService;                        

        public Carrier findRootCarrier() {
            List<Carrier> topLevelCarriers = carrierService.findTopLevelCarriers(); // carrierService is null
        }
}

I assumed PostConstruct gets called after all the dependencies including nested ones gets injected. Am I wrong?

Edit

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jobRepository': Invocation of init method failed; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:137)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:409)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1626)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:518)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:496)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:627)
    at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:169)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:318)
    ... 575 more
Caused by: java.lang.NullPointerException
    at com.****.util.JobUtil.findRootCarrier(JobUtil.java:161)
    at com.****.scheduler.jobs.JobRepository.getBatchJobsForm(JobRepository.java:137)
    at com.****.scheduler.jobs.JobRepository.init(JobRepository.java:84)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:366)
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:311)
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:134)
    ... 592 more

`CarrierService` is `@Autowired` to `JobUtil`. If `jobUtil.carrierService` were `null`, the `JobRepository::init` shouldn't even run I think. — narendra-choudhary, Apr 29 '20 at 08:44
What is the exact error message returned by program? Can you add detailed error with relevant part of stack trace? — narendra-choudhary, Apr 29 '20 at 08:46
@narendra-choudhary I've edit my question and added the error. I was under the same impression as you. the JobRepository::init shouldn't even run I think. But now I am confused — Drunken Daddy, Apr 29 '20 at 09:14
Tragically PostConstruct's can have half instantiated objects when there are circular dependencies: https://stackoverflow.com/a/64649202/32453 — rogerdpack, Nov 02 '20 at 18:40

@PostConstruct: Nested dependency is null

0 Answers0