I wrote this code in order to return a http status of not found to my users in case the resource is not present in the DB.

public class ExampleController {

    public final ExampleService exampleService;

    public ExampleController(ExampleService exampleService) {
        this.exampleService = exampleService;

    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    public class ResourceNotFoundException extends RuntimeException {

    public ExampleDto getExampleById(@PathVariable String id) {
        Example example = exampleService.findById(id).orElse(null   );
        if (example == null) throw new ResourceNotFoundException();
        return new ExampleDto(example);


I would like to know if this code can be considered good and robust enough or if it can be improved and how.

  • 1
    \$\begingroup\$ Please do not update the code in your question to incorporate feedback from answers, doing so goes against the Question + Answer style of Code Review. This is not a forum where you should keep the most updated version in your question. Please see what you may and may not do after receiving answers. \$\endgroup\$
    – Mast
    Commented May 20, 2020 at 7:20
  • \$\begingroup\$ FYI, you don't need to type @Autowired on constructor injection. Cheers just saved 2 line of code in each Component \$\endgroup\$
    – gtiwari333
    Commented Jun 1, 2020 at 22:35

2 Answers 2


Your URL path isn't very RESTlike. You have built the URL to describe an operation when a more common approach is to build the URL to describe a resource.

So instead of https://example.com/api/mappings/get-by-id/42 one would build a URL like https://example.com/api/mappings/42.

The name get-by-id is fully redundant in REST world as the "get" operation is already defined in the HTTP GET-method (the @GetMapping annotation in Spring Boot) and identifying resources by their identifier is always the default operation :).

  • \$\begingroup\$ While that is correct this is a specific case where you can get an item by a property that I called id here but it was just to write an example. The key part of my question if how to handle the 404. Thanks for your contribution in any case! \$\endgroup\$
    – Pitto
    Commented May 20, 2020 at 6:44
  • \$\begingroup\$ Ps I have made my pseudocode more precise regarding your observation. xxxId is a specific property of my object, therefore the route I specified. \$\endgroup\$
    – Pitto
    Commented May 20, 2020 at 6:59
  • \$\begingroup\$ Still you have a very valid point, +1 \$\endgroup\$
    – Pitto
    Commented May 20, 2020 at 7:17

As often happens after sleeping on it I had a better solution:


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