RetrofitApiServiceWithMoshiAndCoroutine.kt

import com.jakewharton.retrofit2.adapter.kotlin.coroutines.CoroutineCallAdapterFactory
import com.squareup.moshi.Moshi
import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
import kotlinx.coroutines.Deferred
import retrofit2.Retrofit
import retrofit2.converter.moshi.MoshiConverterFactory
import retrofit2.http.GET

private const val BASE_URL = "PUT_HERE_URL"

private val retrofit = Retrofit.Builder()
        .addConverterFactory(MoshiConverterFactory.create(
            Moshi.Builder()
                    .add(KotlinJsonAdapterFactory())
                    .build()
        ))
        .addCallAdapterFactory(CoroutineCallAdapterFactory())
        .baseUrl(BASE_URL)
        .build()

interface ApiService {
    @GET("PUT_HERE_GET_VALUE")
    fun get():
            Deferred<List<String>>
}

object Api {
    val retrofitService: ApiService by lazy { retrofit.create(ApiService::class.java) }
}

Retrofit Sample using Coroutine

Created a retrofit object pointing to the desired BASE_URL using a Moshi converter. An interface that expose the get() method, where @get annotation indicates the endpoint will be requested with the GET HTTP method, it returns a Coroutine Deferred List of String which can be fetched with await() if in a Coroutine scope.

Usage

CoroutineScope(Dispatchers.IO).launch {
    val getDeferred = Api.retrofitService.get()
    try {
        // Success
    } catch (e: Exception) {
        // Failure
    }