Spring RestTemplate and generic types ParameterizedTypeReference collections like List<T>

Question

An Abstract controller class requires List of objects from REST. While using Spring RestTemplate its not mapping it to required class instead it returns Linked HashMAp

 public List<T> restFindAll() {      RestTemplate restTemplate = RestClient.build().restTemplate();     ParameterizedTypeReference<List<T>>  parameterizedTypeReference = new ParameterizedTypeReference<List<T>>(){};     String uri= BASE_URI +"/"+ getPath();      ResponseEntity<List<T>> exchange = restTemplate.exchange(uri, HttpMethod.GET, null,parameterizedTypeReference);     List<T> entities = exchange.getBody();     // here entities are List<LinkedHashMap>     return entities;  } 

If I use,

ParameterizedTypeReference<List<AttributeInfo>>  parameterizedTypeReference =      new ParameterizedTypeReference<List<AttributeInfo>>(){};     ResponseEntity<List<AttributeInfo>> exchange =   restTemplate.exchange(uri, HttpMethod.GET, null,parameterizedTypeReference); 

It works fine. But can not put in all subclasses, any other solution.

Answer 1

I worked around this using the following generic method:

public <T> List<T> exchangeAsList(String uri, ParameterizedTypeReference<List<T>> responseType) {     return restTemplate.exchange(uri, HttpMethod.GET, null, responseType).getBody(); } 

Then I could call:

List<MyDto> dtoList = this.exchangeAsList("http://my/url", new ParameterizedTypeReference<List<MyDto>>() {}); 

This did burden my callers with having to specify the ParameterizedTypeReference when calling, but meant that I did not have to keep a static mapping of types like in vels4j's answer