Further reading

With the help of custom annotations inside the Retrofit interface, this library hides most of the complexity associated with handling network requests. We've seen that with simple GET requests in our RestaurantsApiService interface when we annotated our request with the @GET annotation:

interface RestaurantsApiService {
    @GET("restaurants.json")
    fun getRestaurants(): Call<List<Restaurant>>
}

Yet apart from plain GET operations, such Retrofit interfaces can also handle other request types, such as PUT, POST, and DELETE.

For example, if you need to define a request that passes some data to the server that is likely to be stored, you can use a POST request by adding the @POST annotation to your desired method:

@POST("user/edit")
fun updateUser(@Field("first_name") firstName: String): 
    Call<User>

To understand how to use Retrofit for...