NullPointerException when trying to read Database Queries in spring batch ItemProcessor

Question

        public class TransactionHistoryCsvItemProcessor  implements ItemStream, ItemProcessor<TransactionHistory,TransactionHistory>{
            @Autowired
            private TransactionHistoryRepository transactionHistoryRepository;
            @Autowired
            private ProductHierarchyRepository productHierarchyRepository;
            @Autowired
            private LocationHierarchyRepository locationHierarchyRepository;


            List<TransactionHistory>list= transactionHistoryRepository.findAll();
            List<String> pLevel7Products = productHierarchyRepository.getPLevel7Ids();
            List<String> level5locations=locationHierarchyRepository.getLevel5Ids();


            int count=1;

            TransactionHistoryCsvItemProcessor(){

            }


            private Set<TransactionHistory> processedData = new HashSet<TransactionHistory>();
            @Override
            public TransactionHistory process(TransactionHistory transactionHistory) throws Exception {

                TransactionHistory processedObj = new TransactionHistory(); 

                    if (pLevel7Products.contains(transactionHistory.getProductId().trim())) {

                        if (level5locations.contains(transactionHistory.getLocationId().trim())) {

                            if(list!=null&&!list.isEmpty()){
                                 if(list.contains(transactionHistory)){
                                     count++;
                                     throw new MyOwnException(" duplicates data error", transactionHistory.getProductId().trim(),
                                                transactionHistory.getLocationId().trim(), transactionHistory.getPeriodId(),
                                                transactionHistory.getQuantity(), "at line numer ", count-1);
                                }
                            }

                                      processedObj.setProductId(transactionHistory.getProductId().trim());
                                        processedObj.setLocationId(transactionHistory.getLocationId().trim());
                                        processedObj.setQuantity(transactionHistory.getQuantity());
                                        processedObj.setPeriodId(transactionHistory.getPeriodId());
                                        processedObj.setCreatedDate(LocalDate.now());
                                        processedData.add(transactionHistory);
                                        transactionHistory.setItemCount(count);
                                        count++;

                        }else {
                            System.out.println("failed location");
                            count++;
                            transactionHistory.setItemCount(count);
                            throw new MyOwnException(" location data error", transactionHistory.getProductId().trim(),
                                    transactionHistory.getLocationId().trim(), transactionHistory.getPeriodId(),
                                    transactionHistory.getQuantity(), "at line numer ", count-1);
                        }
                    } else {
                        System.out.println("failed product");
                        // count++;
                        try {
                            transactionHistory.setItemCount(count);
                            throw new MyOwnException(" product data error", transactionHistory.getProductId().trim(),
                                    transactionHistory.getLocationId().trim(), transactionHistory.getPeriodId(),
                                    transactionHistory.getQuantity(), "at line numer ", count);
                        } catch (MyOwnException e) {
                            System.out.println("product error");
                            throw new MyOwnException(" product data error", transactionHistory.getProductId().trim(),
                                    transactionHistory.getLocationId().trim(), transactionHistory.getPeriodId(),
                                    transactionHistory.getQuantity(), "at line numer ", count);

                        } finally {
                            count++;
                        }
                    }

                //}

                if (processedObj.getProductId() == null && processedObj.getLocationId() == null)
                    return null;
                else {
                    // processedData.add(processedObj);
                    return processedObj;
                }
            }

            @Override
            public void open(ExecutionContext executionContext) throws ItemStreamException {
                // TODO Auto-generated method stub
                //list=transactionHistoryRepository.findAll();
            }
            @Override
            public void update(ExecutionContext executionContext) throws ItemStreamException {
                // TODO Auto-generated method stub  
            }
            @Override
            public void close() throws ItemStreamException {
                // TODO Auto-generated method stub
                count=1;    
            }
        }
    //============================================//
    @Bean
        public Step transactionHistoryStep() {
            return  ((SimpleStepBuilder<TransactionHistory, TransactionHistory>) stepBuilderFactory.get("transactionHistoryStep")
                    .<TransactionHistory,TransactionHistory>chunk(10)
                    .reader(reader())
                    .processor(processor())
                    .writer(writer())
                    .stream(new TransactionHistoryCsvItemProcessor()))
                    .faultTolerant()
                    .skipPolicy(transactionHistoryCsvImportSkipPolicy)
                    .build();

        }


        @Bean
        @JobScope
        public FlatFileItemReader<TransactionHistory> reader() {
            FlatFileItemReader<TransactionHistory> flatFileItemReader= new FlatFileItemReader<TransactionHistory>();
            try {

                TransactionHistoryFieldSetMapper transactionHistoryFieldSetMapper= new TransactionHistoryFieldSetMapper();

                flatFileItemReader.setResource(new FileSystemResource(FileResources.mappingFileResouces("transactionHistoryImportCsvFile")));
                flatFileItemReader.setName("CSV-Reader");
                flatFileItemReader.setLinesToSkip(1);
                flatFileItemReader.setLineMapper(new DefaultLineMapper<TransactionHistory>(){{
                    setLineTokenizer(new DelimitedLineTokenizer() {{
                        setNames("productId","locationId","periodId","quantity");
                        setFieldSetMapper(transactionHistoryFieldSetMapper);

                    }});
                    setFieldSetMapper(new TransactionHistoryFieldSetMapper(){{
                        //setTargetType(TransactionHistory.class);

                    }});
                }});
            }
            catch(Exception e) {
                e.printStackTrace();
                logger.error("read error"+flatFileItemReader);
            }

            return flatFileItemReader;
        }


         @Bean
         public ItemProcessor<TransactionHistory, TransactionHistory> processor() {
               return new TransactionHistoryCsvItemProcessor();
            }

//===========error ====//

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled. 2020-May-05 22:30:13.654 ERROR [main] o.s.b.SpringApplication - Application run failed org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'transactionHistoryController': Unsatisfied dependency expressed through field 'transactionHistoryCsvImportJob'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionHistoryJob' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.core.Job]: Factory method 'transactionHistoryJob' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionHistoryStep' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.core.Step]: Factory method 'transactionHistoryStep' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processor' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemProcessor]: Factory method 'processor' threw exception; nested exception is java.lang.NullPointerException at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:596) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1411) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:845) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:743) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:390) at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1214) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1203) at com.datalabsindia.ScpApplication.main(ScpApplication.java:21) Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionHistoryJob' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.core.Job]: Factory method 'transactionHistoryJob' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionHistoryStep' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.core.Step]: Factory method 'transactionHistoryStep' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processor' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemProcessor]: Factory method 'processor' threw exception; nested exception is java.lang.NullPointerException at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:627) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:456) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1321) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1160) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1251) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1171) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:593) ... 19 common frames omitted Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.core.Job]: Factory method 'transactionHistoryJob' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionHistoryStep' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.core.Step]: Factory method 'transactionHistoryStep' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processor' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemProcessor]: Factory method 'processor' threw exception; nested exception is java.lang.NullPointerException at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:622) ... 32 common frames omitted Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionHistoryStep' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.core.Step]: Factory method 'transactionHistoryStep' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processor' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemProcessor]: Factory method 'processor' threw exception; nested exception is java.lang.NullPointerException at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:627) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:456) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1321) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1160) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.resolveBeanReference(ConfigurationClassEnhancer.java:394) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:366) at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6.transactionHistoryStep() at com.datalabsindia.batch.TransactionHistoryCsvImport.transactionHistoryJob(TransactionHistoryCsvImport.java:97) at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6.CGLIB$transactionHistoryJob$3() at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6$$FastClassBySpringCGLIB$$d1625b5b.invoke() at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6.transactionHistoryJob() at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ... 33 common frames omitted Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.core.Step]: Factory method 'transactionHistoryStep' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processor' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemProcessor]: Factory method 'processor' threw exception; nested exception is java.lang.NullPointerException at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:622) ... 56 common frames omitted Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processor' defined in class path resource [com/datalabsindia/batch/TransactionHistoryCsvImport.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemProcessor]: Factory method 'processor' threw exception; nested exception is java.lang.NullPointerException at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:627) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:456) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1321) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1160) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.resolveBeanReference(ConfigurationClassEnhancer.java:394) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:366) at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6.processor() at com.datalabsindia.batch.TransactionHistoryCsvImport.transactionHistoryStep(TransactionHistoryCsvImport.java:105) at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6.CGLIB$transactionHistoryStep$4() at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6$$FastClassBySpringCGLIB$$d1625b5b.invoke() at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6.transactionHistoryStep() at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ... 57 common frames omitted Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemProcessor]: Factory method 'processor' threw exception; nested exception is java.lang.NullPointerException at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:622) ... 80 common frames omitted Caused by: java.lang.NullPointerException: null at com.datalabsindia.batch.TransactionHistoryCsvItemProcessor.(TransactionHistoryCsvItemProcessor.java:55) at com.datalabsindia.batch.TransactionHistoryCsvImport.processor(TransactionHistoryCsvImport.java:160) at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6.CGLIB$processor$2() at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6$$FastClassBySpringCGLIB$$d1625b5b.invoke() at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) at com.datalabsindia.batch.TransactionHistoryCsvImport$$EnhancerBySpringCGLIB$$669179a6.processor() at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ... 81 common frames omitted

it is working fine if i put repository queries inside process method. but i do not want to do that — srikanth madhira, May 05 '20 at 17:19
welcome to stackoverflow. take a tour and get first badge - https://stackoverflow.com/tour — Hemant, May 06 '20 at 15:35

score 0 · Answer 1 · answered May 11 '20 at 19:41

The exception you are encountering is due to your attempt to use an @Autowired dependency before you have any guarantees that that dependency has been injected into your TransactionHistoryCsvItemProcessor object.

Factory method 'processor' threw exception; nested exception is java.lang.NullPointerException at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:596)

These are the problematic lines:

List<TransactionHistory>list= transactionHistoryRepository.findAll();
List<String> pLevel7Products = productHierarchyRepository.getPLevel7Ids();
List<String> level5locations=locationHierarchyRepository.getLevel5Ids();

If you need to do some additional initialization of your TransactionHistoryCsvItemProcessor object, the easiest thing to do is have TransactionHistoryCsvItemProcessor implement InitializingBean, and then initialize your Lists in the overridden method afterPropertiesSet.

For example,

public class TransactionHistoryCsvItemProcessor 
    implements InitializingBean, ItemStream, ItemProcessor<TransactionHistory,TransactionHistory>{

    @Autowired
    private TransactionHistoryRepository transactionHistoryRepository;
    @Autowired
    private ProductHierarchyRepository productHierarchyRepository;
    @Autowired
    private LocationHierarchyRepository locationHierarchyRepository;

    List<TransactionHistory> list;
    List<String> pLevel7Products;
    List<String> level5locations;

    // ...implementation omitted for brevity

    @Override
    public void afterPropertiesSet() throws Exception {
        // typical null checks would also be prudent
        list = transactionHistoryRepository.findAll();
        pLevel7Products = productHierarchyRepository.getPLevel7Ids();
        level5locations = locationHierarchyRepository.getLevel5Ids();
    }

}

thanks for the answer philip, I tried with @PostConstruct but it is called only once after application starts, if i change the data in database then repository will not fetch modified data.Does public void afterPropertiesSet() call only once or Everytime when we call spring batch or any specific endpoint. excecuse me if i wrote bad english — srikanth madhira, May 13 '20 at 12:18
```afterPropertiesSet()``` is only called once, as well. If you need to continually pull fresh data from your database, then I recommend placing these repository method calls in your ```process()``` method. — Philip Wrage, May 13 '20 at 14:36
But if I place repository findAll queries in process, for each item I don't want to fetch all the data as data is huge in size. Any alternative.... — srikanth madhira, May 14 '20 at 15:07
I see. That can definitely be a problem. I have successfully used the [Driving Query Pattern](https://docs.spring.io/spring-batch/docs/current/reference/html/common-patterns.html#drivingQueryBasedItemReaders) in my own work where the volume of data was too much to handle with the canonical `ItemReader` approach. — Philip Wrage, Jun 19 '20 at 23:46

NullPointerException when trying to read Database Queries in spring batch ItemProcessor

1 Answers1