Get T generic type of the class to the T in the new GenericType<List<T>>() Java

Question

I have implmented the follwing class and implemented a search method get list of Object for the given type of T using a REST call.

    public class AmapiService<T extends Resource> implements RestService<T> {


    @Override
    public List<T> search( MultivaluedMap<String, String> aQueryParams ) {
          MultivaluedMap<String, String> lQueryParams = aQueryParams;
          Client lClient = buildClient();

      WebTarget ltarget = lClient.target( iRestDriver.target( aApiUrl ).getUri() );

      for ( String lKey : lQueryParams.keySet() ) {
         ltarget = ltarget.queryParam( lKey, lQueryParams.getFirst( lKey ) );
      }

      List<T> lObjects = null;

      lObjects = ltarget.request( MediaType.APPLICATION_JSON ).get( new GenericType<List<T>>() {
      } );

      return lObjects;
   }
}

this is how the instance is created for the class and search method call.

AmapiService<RFQDefinition> RFQService =
            new AmapiService<RFQDefinition>();

List<RFQDefinition> qfq = RFQService.search( lQueryParam );

when i run this im getting the following error

May 07, 2018 1:48:14 PM org.glassfish.jersey.message.internal.ReaderInterceptorExecutor$TerminalReaderInterceptor aroundReadFrom
SEVERE: MessageBodyReader not found for media type=application/json, type=interface java.util.List, genericType=java.util.List<T>.

That means the RFQDefinition does not set to the T in the new GenericType<List<T>>().

how can i set the type from the T in the AmapiService<T extends Resource> to new GenericType<List<T>>()

if i define it new GenericType<List<RFQDefinition>>() Instead of T its working

Answer 1

I have changed the Search method Implementation like this, now it is working. iClass you can take this as a parameter eg: RFQDefinition.class

ObjectMapper mapper = new ObjectMapper();
      JavaType type = mapper.getTypeFactory().constructCollectionType( List.class, iClass );
      List<T> lObjects = null;

      JsonArray lResponse = ltarget.request( MediaType.APPLICATION_JSON ).get( JsonArray.class );
      try {
         lObjects = mapper.readValue( lResponse.toString(), type );
      } catch ( JsonParseException e ) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      } catch ( JsonMappingException e ) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      } catch ( IOException e ) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }