Kotlin call java method with Class argument

Question

I want to use Spring RestTemplate in Kotlin like this:

//import org.springframework.web.client.RestTemplate
fun findAllUsers(): List {
          


        

Answer 1

I think you need to actually use the RestTemplate.exechange method that has a signature that accepts a ParameterizedTypeReference where T can be the generic type of your response (in your case a List)

Suppose I have an endpoint that returns a list of Jedi names in JSON format, as follows

["Obi-wan","Luke","Anakin"]

And I would like to invoke this endpoint and get a List as the result, with the list containing the Jedi names from the JSON.

Then I can do this:

val endpoint = URI.create("http://127.0.0.1:8888/jedi.json")
val request = RequestEntity(HttpMethod.GET, endpoint)
val respType = object: ParameterizedTypeReference>(){}
val response = restTemplate.exchange(request, respType)
val items: List = response.body;
println(items) //prints [Obi-wan, Luke, Anakin]

Notice that my ParameterizedTypeReference has a type argument of List. That's what does the trick.

And that worked for me when I tried it.