How to use RestTemplate to get result in List and put the response into List?

Question

Hi what i trying to achieve is i want to consume other API and put some response data into List in my function using RestTemplate, here is how my code look like :

@PostMapping("/save-new")
public ResponseEntity<ShipmentAddressGrouping> saveNewShipmentAddressGrouping(@Valid @RequestBody InputRequest<ShipmentAddressGroupingDto> request) {
    String url = baseUrl + "/load-list";

    HttpEntity<PartnerShipmentDto> requestPartnerShipmentDto = new HttpEntity<>(new PartnerShipmentDto());
    RestTemplate restTemplate = new RestTemplate();
    List<PartnerShipmentDto> partnerShipmentDto = restTemplate.postForObject(url, requestPartnerShipmentDto, new ParameterizedTypeReference<List<PartnerShipmentDto>>() {});

    ShipmentAddressGrouping newShipmentAddressGrouping = shipmentAddressGroupingService.save(request);
    return ResponseEntity.ok(newShipmentAddressGrouping);

}

as you can see i try to get the response in to List, which is i try here restTemplate.postForObject(url, requestPartnerShipmentDto, new ParameterizedTypeReference<List<PartnerShipmentDto>>() {});

but i got error underlined in restTemplate.postForObject that look like this :

The method postForObject(String, Object, Class, Object...) in the type RestTemplate is not applicable for the arguments (String, HttpEntity, new ParameterizedTypeReference<List>(){})

What should i change to fix this?

Answer 1

If you want to use ParameterizedTypeReference<T>, you need to use RestTemplate.exchange(), since this is the only Method that exposes a parameter of type ParameterizedTypeReference<T>.

List<PartnerShipmentDto> partnerShipmentDto = restTemplate.exchange(url, 
                HttpMethod.GET, 
                requestPartnerShipmentDto,
                new ParameterizedTypeReference<List<PartnerShipmentDto>>() {})
        .getBody();