Null Pointer Exception

[Eleni Pap]

I would like to make a call on my Controller in order to retrieve some data. For example I want to get the Data until the date,which user will give and by id of product(barcode).

 

  @GetMapping("/retrieval/products")
    public List<Retrieval> findByRetrieval(@RequestParam("toDate") String toDate, @RequestParam("barcode") String barcode) throws ParseException {

        SimpleDateFormat formatter6=new SimpleDateFormat("yyyy-MM-dd");
        Date to = formatter6.parse(toDate);

        return retrievalRepository.findByProductBarcodeAndDate(barcode,to);
    } 

in line : findByProductBarcodeAndDate  on debug it returns me nullpointer exception.
Cannot find local variable findByProductBarcodeAndDate  .

How I could handle it ?

I also have have on my Service layer:

    public List<RetrievalDTO> findByProductBarcodeAndDate(String barcode, Date toDate)
    {
        List<Retrieval> list=retrievalRepository.findByProductBarcodeAndDate(barcode,toDate);
        List<RetrievalDTO> listDTO=new ArrayList<>();
        for(Retrieval retrieval:list){
            RetrievalDTO dto=new RetrievalDTO(retrieval);
            listDTO.add(dto);
        }
        return  listDTO;
    }

Thank you in advance!!

[Dave Tolls]

Can you post the full exception text including stack trace, and point out which line of your code it is thrown from.

[Eleni Pap]

package com.demo.warehouse.controller;

import com.demo.warehouse.dao.ProductRepository;
import com.demo.warehouse.dao.RetrievalRepository;
import com.demo.warehouse.dto.RetrievalDTO;
import com.demo.warehouse.service.ProductService;
import com.demo.warehouse.service.RetrievalServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.web.bind.annotation.*;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

@RestController
@RequestMapping("/api")
public class RetrievalController {

    @Autowired
    private ProductService productService;
    @Autowired
    private ProductRepository productRepository;


    private RetrievalServiceImpl retrievalService;
    private RetrievalRepository retrievalRepository;



    @GetMapping("/search")
    public List<RetrievalDTO> searchRetrievals(@RequestParam @DateTimeFormat(pattern="yyyy/MM/dd") Date toDate,
                                                       @RequestParam String barcode )
    {
        return retrievalService.findByProductBarcodeAndDate(barcode, toDate);
    }

    @GetMapping("/retrieval/products")
    public List<RetrievalDTO> findByRetrieval(@RequestParam("barcode") String barcode, @RequestParam("toDate") String toDate ) throws ParseException {

        SimpleDateFormat formatter6=new SimpleDateFormat("yyyy-MM-dd");
        Date to = formatter6.parse(toDate);

        List<RetrievalDTO> retrievalDTOS= new ArrayList<>();

        if (retrievalService == null) {
            System.out.println("  is null");
        } else {
            retrievalDTOS= retrievalService.findByProductBarcodeAndDate(barcode, to);

        }
        return retrievalDTOS;
    }
}

package com.demo.warehouse.dao;

import com.demo.warehouse.entity.Product;
import com.demo.warehouse.entity.Retrieval;
import com.demo.warehouse.entity.Shelf;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import java.util.Date;
import java.util.List;

@Repository
public interface RetrievalRepository extends JpaRepository<Retrieval,Long>{

    Retrieval findByProductAndShelfAndDate(Product product, Shelf shelf, Date date);
    List<Retrieval> findByProductBarcodeAndDate(String barcode,Date toDate);
    Retrieval findByDate(Date toDate);

}

package com.demo.warehouse.dto;

import com.demo.warehouse.entity.Product;
import com.demo.warehouse.entity.Retrieval;
import com.demo.warehouse.entity.Shelf;

import java.math.BigDecimal;
import java.sql.Date;
import java.util.ArrayList;
import java.util.List;

public class RetrievalDTO {


    private Long id;
    private  Date toDate;
    private BigDecimal stock;





    private ShelfDTO shelfDTO;
    private ProductDTO productDTO;

    private static List<RetrievalDTO> retrievalDTOList = new ArrayList<>();



    public RetrievalDTO(Retrieval retrieval) {
        this.id = retrieval.getId();
        this.stock = retrieval.getStock();
        this.toDate = retrieval.getDate();
        this.shelfDTO=new ShelfDTO(retrieval.getShelf());
        this.productDTO= new ProductDTO(retrieval.getProduct());

    }

    public BigDecimal getStock() {
        return stock;
    }

    public void setStock(BigDecimal stock) {
        this.stock = stock;
    }

    public ShelfDTO getShelfDTO() {
        return shelfDTO;
    }

    public void setShelfDTO(ShelfDTO shelfDTO) {
        this.shelfDTO = shelfDTO;
    }

    public ProductDTO getProductDTO() {
        return productDTO;
    }

    public void setProductDTO(ProductDTO productDTO) {
        this.productDTO = productDTO;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Date getToDate() {
        return toDate;
    }

    public void setToDate(Date toDate) {
        this.toDate = toDate;
    }
}

package com.demo.warehouse.entity;

import com.demo.warehouse.dto.WarehouseDTO;

import javax.persistence.*;
import java.math.BigDecimal;
import java.sql.Date;
import java.util.List;
//retrieval

@Entity
@Table(name = "retrieval")
public class Retrieval {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    Long id;

    @Column(name="stock")
    private BigDecimal stock;

    public BigDecimal getStock() {
        return stock;
    }

    public void setStock(BigDecimal stock) {
        this.stock = stock;
    }

    @Column(name = "date")
    private Date date;

    @ManyToOne
    @JoinColumn(name = "product_barcode")
    private Product product;

    @ManyToOne
    @JoinColumn(name = "shelf_id")
    private Shelf shelf;


    public Retrieval( ) {

    }

    public Retrieval( BigDecimal stock, Date date) {
        this.stock = stock;
        this.date = date;
//        this.product = product;
//        this.shelf = shelf;
    }

    public Product getProduct() {
        return product;
    }

    public void setProduct(Product product) {
        this.product = product;
    }

    public Shelf getShelf() {
        return shelf;
    }

    public void setShelf(Shelf shelf) {
        this.shelf = shelf;
    }




    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

}

package com.demo.warehouse.service;

import com.demo.warehouse.dto.InvoiceDTO;
import com.demo.warehouse.dto.RetrievalDTO;
import com.demo.warehouse.entity.Retrieval;

import java.util.Date;
import java.util.List;

public interface RetrievalService {


    Retrieval dtoToEntity(RetrievalDTO retrievalDTO);

    public RetrievalDTO findById(Long id);

    public List<RetrievalDTO> findByProductBarcodeAndDate(String barcode, Date toDate);

}

package com.demo.warehouse.service;

import com.demo.warehouse.dao.InvoiceRepository;
import com.demo.warehouse.dao.ProductRepository;
import com.demo.warehouse.dao.RetrievalRepository;
import com.demo.warehouse.dao.ShelfRepository;
import com.demo.warehouse.dto.*;
import com.demo.warehouse.entity.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestParam;

import javax.print.DocFlavor;
import javax.swing.*;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Optional;

@Service
public class RetrievalServiceImpl implements RetrievalService {

    @Autowired
    private ProductServiceImpl productService;

    private  RetrievalServiceImpl retrievalService;

    @Autowired
    private ProductRepository productRepository;
    @Autowired
    private ShelfRepository shelfRepository;

    @Autowired
    private ShelfServiceImpl shelfService;
    @Autowired
    private InvoiceServiceImpl invoiceService;
    @Autowired
    private RetrievalRepository retrievalRepository;
    @Autowired
    private InvoiceRepository invoiceRepository;
    private Long id;

    public Retrieval dtoToEntity(RetrievalDTO retrievalDTO) {
        Retrieval retrieval = new Retrieval();
        retrieval.setId(retrievalDTO.getId());
        retrieval.setDate(retrievalDTO.getToDate());
        retrieval.setProduct(productService.dtoToEntity(retrievalDTO.getProductDTO()));
        retrieval.setShelf(shelfService.DTOtoEntity(retrievalDTO.getShelfDTO()));
        retrieval.setProduct(productService.dtoToEntity(retrievalDTO.getProductDTO()));
        return retrieval;
    }


    @Override
    public RetrievalDTO findById(Long id) {

        Optional<Retrieval> result = retrievalRepository.findById(id);
        Retrieval retrieval = null;

        if (result.isPresent())
            retrieval = result.get();
        else {
            throw new RuntimeException("Did not find  id - " + id);
        }
        RetrievalDTO retrievalDTO = new RetrievalDTO(retrieval);
        return retrievalDTO;

    }

    @Override
    public List<RetrievalDTO> findByProductBarcodeAndDate(String barcode, Date toDate)
    {
        List<Retrieval> list=retrievalRepository.findByProductBarcodeAndDate(barcode,toDate);
        List<RetrievalDTO> listDTO=new ArrayList<>();
        for(Retrieval retrieval:list){
            RetrievalDTO dto=new RetrievalDTO(retrieval);
            listDTO.add(dto);
        }
        return  listDTO;
    }

}

Postman:

"status": 500,
   "error": "Internal Server Error",
   "trace": "java.lang.NullPointerException\r\n\tat com.demo.warehouse.controller.RetrievalController.searchDoctorAppointments(RetrievalController.java:59)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)\r\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\r\n\tat java.lang.reflect.Method.invoke(Method.java:498)\r\n\tat org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)\r\n\tat org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHan
.....
Console

java.lang.NullPointerException: null
at com.demo.warehouse.controller.RetrievalController.searchRetrievals(RetrievalController.java:59) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_251]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_251]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_251]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_251]



findByProductBarcodeAndDate is null

[Eleni Pap]

i forgot @Autowired at my Controller

@Autowired
   private RetrievalServiceImpl retrievalService;

But still have problems,

java.lang.NullPointerException\r\n\tat com.demo.warehouse.controller.RetrievalController.findByRetrieval(RetrievalController.java:77)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)\r\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(

[Dave Tolls]

I think you missed the bit where I said to point out where in your code it is thrown from.

Your Controller has no line 77.

[Tim Holloway]

Actually, what Dave was asking for was a full stack trace, not the full application listing. Too much code is as bad as too little. Worse, really, because too little and we'll ask for more, but too much and it's better just to skip over it. Well, actually, a full stack trace is usually pretty long, but we're used to being able to skip quickly to the important parts.

However, your lastest exception is on line 77 of something that's posted with only about 40-something lines in it. If you could let us know which line in RetrievalController is supposed to be line 77, we can say more.

[Himai Minh]

Hi, Eleni,
In your Retrieval class, there is no attribute called productbarcode. Instead, there is an attribute called product.
So, if your repository, you may want to define a method called findByProductAndDate() instead of findByProductbarcodeAndDate.

[Mike Simmons]

So, your original problem was with the retrievalService, which was not autowired, and so was still null when you tried to use it.  It looks like you're now having the same problem with retrievalRepository.  Which probably has the same solution...

[Eleni Pap]

Thank you all!!

Yes the problem was Autowired. Thank for your time.

[Himai Minh]

Hi, I am wondering why findByProductBarcodeAndDate works.
In the Retrieval class, there is no attribute called productBarcode.

[Himai Minh]

I can answer my own question. The product has a join column called product_barcode. That is why findByProductBarcode still works.