[FIXED] Spring Batch application - Getting Null Pointer Application while invoking Spring Boot application

Issue

I have BatchConfiguration , OrderProcesser and OrderReader Class file. When I am calling Spring Boot rest service, I get a NullPointerException.

But, when I run the SpringBoot application in Postman, it is displaying appropriate results. Also, I would like to know which step make it run multiple times , so that billerOrderId gets executed multiple times. I used https://spring.io/guides/gs/batch-processing/ to write my code .

Here is my osm-billers.csv

BillerOrderId
1233
2344
4566

@Configuration
@EnableBatchProcessing
public class BatchConfiguration  {
  @Autowired
  public JobBuilderFactory jobBuilderFactory;
  
  @Autowired
  public StepBuilderFactory stepBuilderFactory;
  
  @Autowired
  private CsvFileToDatabaseJobConfig csvFileToDatabaseJobConfig;
  
  @Autowired
  private DatabaseToCsvFileJobConfig databaseToCsvFileJobConfig;
  
  RestTemplate restTemplate;
  
  
  @Bean
  public FlatFileItemReader<Biller> reader(){
   try {
      FlatFileItemReader<Biller> itemReader = csvFileToDatabaseJobConfig.csvFileItemReader();     
      return itemReader ;
    } catch (UnexpectedInputException e) {
        throw new OrderBatchException("Invalid Input..." + e.getMessage());
    } catch (ParseException e) {
        throw new OrderBatchException("Parsing error..." + e.getMessage());
    } catch (NonTransientResourceException e) {
        throw new OrderBatchException("NonTransientReasource error..." + e.getMessage());
    } catch (Exception e) {
        throw new OrderBatchException("Unknown Read error..." + e.getMessage());
    }
    
  }
  
  @Bean
  public OrderProcessor processor() {
      return new OrderProcessor();
  }
  
  @Bean
  public ItemWriter<Biller> writer() {
      try {
          ItemWriter<Biller> itemWriter = databaseToCsvFileJobConfig.databaseCsvItemWriter();
          return itemWriter;
      } catch (Exception e) {
          throw new OrderBatchException("Unknown Write error..." + e.getMessage());
      }
    
  }
  
  @Bean
  public Job importJobOrder(JobCompletionNotificationListner listener, Step step1) {
      return jobBuilderFactory.get("importJobOrder")
              .incrementer(new RunIdIncrementer())
              .listener(listener)
              .flow(step1)
              .end()
              .build(); 
  }
  
  @Bean
  public Step step1(ItemWriter<Biller> writer) {
      return stepBuilderFactory.get("step1")
              .<Biller, Biller> chunk(10)
              .reader((ItemReader<? extends Biller>) reader())
              .processor(processor())
              .writer(writer)
              .build();
  }
 
}

package com.spectrum.sci.processor;

import java.util.List;

import org.springframework.batch.item.ItemProcessor;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.client.RestTemplate;

import com.spectrum.sci.model.Biller;
import com.spectrum.tos.model.Order;
import com.spectrum.tos.model.OrderRequest;
import com.spectrum.tos.model.OrderResponse;

public class OrderProcessor implements ItemProcessor<Biller, Biller>{
    
    @Value("${osm.service.url}")
    private String orderUrl; 
    
    @Value("${osm.service.username}")
    private String userName;
    
    @Value("${osm.service.password}")
    private String password;
    
    RestTemplate restTemplate;
      
    @Override
    public Biller process(Biller biller) throws Exception {  
          OrderRequest orderRequest = new OrderRequest();
          Order order = new Order();
          order.setBillerOrderId(biller.getBillerOrderId());
          orderRequest.setOrder(order);
          OrderReader osmReader = new OrderReader(orderUrl, userName, password, restTemplate, orderRequest);    
          OrderResponse orderResponse = osmReader.read();
          
          if (orderResponse.getResult().equals("SUCCESS") ) {
              return null;
          } else {
              //Failed transactions
              return biller;
          } 
         
    }

}



public class OrderReader implements ItemReader<OrderResponse>{
    
    private static final Logger log = LoggerFactory.getLogger(OrderReader.class);

    private final String apiUrl;
    private final RestTemplate restTemplate;
    
    private int nextOrderIndex;
    private OrderResponse orderResponse;
    
    @Autowired
    private OrderRequest orderRequest;
    
    private String userName;
    private String password;

    
    public OrderReader(String apiUrl, String userName, String password, RestTemplate restTemplate, OrderRequest orderRequest) {
        this.apiUrl = apiUrl;
        this.restTemplate = restTemplate;
        this.orderRequest = orderRequest;
        this.userName = userName;
        this.password = password;
        nextOrderIndex = 0;
    }
    
    private boolean orderisNotInitialized() {
        return this.orderResponse == null;
    }
    
    private OrderResponse fetchOrderDataFromApi(OrderRequest orderRequest) {
        // log.info("OrderRequest = " + orderRequest.getOrder().getBillerOrderId());
         log.info("apiUrl = " + apiUrl); 
         log.info("userName = " + userName);
         
         HttpHeaders headers  = new HttpHeaders();
         headers.setContentType(MediaType.APPLICATION_JSON);
         headers.setAccept(Collections.singletonList(MediaType.APPLICATION_JSON));
         headers.setBasicAuth(userName, password);
         
         HttpEntity<OrderRequest> requestEntity =
                 new HttpEntity<OrderRequest>(orderRequest, headers);
         
         ResponseEntity<OrderResponse> response = 
                 restTemplate.exchange(apiUrl,HttpMethod.POST, requestEntity,OrderResponse.class);
         
         log.info("response = " + response);
         
         //ResponseEntity<OrderResponse[]> response = restTemplate.postForEntity(apiUrl, orderRequest, OrderResponse[].class);
         OrderResponse orderResponse = response.getBody();
         //return Arrays.asList(orderResponse);
         return orderResponse;
    }
    
    @Override
    public OrderResponse read()
            throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException {
        if (orderisNotInitialized()) {
            orderResponse = fetchOrderDataFromApi(orderRequest);
        }
        /*  
        OrderResponse nextOrder = null;
        
        if (nextOrderIndex < orderResponse.size()) {
            nextOrder = orderResponse.get(nextOrderIndex);
            nextOrderIndex++;
        } 
        return nextOrder; */
        return orderResponse;
    }

}

Here is the error.

    main] o.s.batch.core.step.AbstractStep         : Encountered an error executing step step1 in job importJobOrder

java.lang.NullPointerException: null
    at com.spectrum.sci.processor.OrderReader.fetchOrderDataFromApi(OrderReader.java:70) ~[classes/:na]
    at com.spectrum.sci.processor.OrderReader.read(OrderReader.java:84) ~[classes/:na]
    at com.spectrum.sci.processor.OrderProcessor.process(OrderProcessor.java:34) ~[classes/:na]
    at com.spectrum.sci.processor.OrderProcessor.process(OrderProcessor.java:1) ~[classes/:na]

Solution

your restTemplate is null, you never initialize it. try with restTemplate = new RestTemplate(); in your OrderProcessor

Answered By - sap
Answer Checked By - Marilyn (JavaFixing Volunteer)