Java – malformed JSON: unexpected ‘<' in spring

I want to make JSON from JPA @ entity. I have

@Entity
@JsonAutoDetect
public class Bar implements Serializable {     
    @Id
    @GeneratedValue
    private Integer id;
    private String title;
    //omitting other stuff
}

My controller is

@RestController
public class BarController {

    @Autowired
    private BarService barService;

    @RequestMapping(value = "/",method = RequestMethod.GET,headers = "Accept=application/json",produces={"application/json"})

    public List<Bar> list() {            
        return barService.findAllBars());
    }

}

I encountered this error in my browser

And at the postman

What's the problem

Solution

I found a fatal error and you got bar barservice The list of findallbars (), you may need to convert the list into JSON and add the method as

public static String toJSON(Object object) 
    { 
        if ( object == null ){
        return "{}"; 
        } 
        try { 
           ObjectMapper mapper = new ObjectMapper(); 
           return mapper.writeValueAsString(object); 
           } 
        catch (Exception e) { 
         e.printStackTrace(); 
        } 
      return "{}"; 
      }

Now change to

@RequestMapping(value = "/",produces={"application/json"})
    public String list() {
        return toJSON(barService.findAllBars());
    }

I hope this works. If you have any questions, feel free to query in the comment session