Unresolved reference : retrofit while creating retrofit instance - android-studio

Question

I am working on an android app which request Mars photos ans use it to display it on screen.
To make an request.And trying to use A public Api object that exposes the lazy-initialized Retrofit service.
below is source code with error
import retrofit2.Retrofit
import retrofit2.converter.scalars.ScalarsConverterFactory
import retrofit2.http.GET
class MarsApiService {
public val retrofit = Retrofit.Builder()
.addConverterFactory(ScalarsConverterFactory.create())
.baseUrl(Companion.BASE_URL)
.build()
interface MarsApiService{
#GET("photos")
fun getPhotos(): String
}
object MarsApi {
val retrofitService: MarsApiService by lazy { retrofit.create(MarsApiService::class.java) }
}
companion object {
private const val BASE_URL = "https://android-kotlin-fun-mars-server.appspot.com"
}
}
17th line the code inside object MarsApi pops up errors Unresolved reference : retrofit. The call to create() function on a Retrofit object is expensive and the app needs only one instance of Retrofit API service. So, i exposed the service to the rest of the app using object declaration.
What I have tried:
The code is working if i bring code inside object MarsApi out but doing so may result in multiple instance of retrofit.

Answer 1

code1
interface MarsApiService {
#GET("photos")
suspend fun getPhotos(): String
companion object {
private const val BASE_URL = "https://android-kotlin-fun-mars-server.appspot.com"
val marsApiService: MarsApiService by lazy {
Retrofit.Builder()
.addConverterFactory(ScalarsConverterFactory.create())
.baseUrl(BASE_URL)
.build().create(MarsApiService::class.java)
}
}
}
code2
private const val BASE_URL = "https://android-kotlin-fun-mars-server.appspot.com/"
private val retrofit = Retrofit.Builder()
.addConverterFactory(ScalarsConverterFactory.create())
.baseUrl(BASE_URL)
.build()
interface MarsApiService {
#GET("photos")
suspend fun getPhotos(): String
}
object MarsApi {
val marsApiService: MarsApiService by lazy { retrofit.create(MarsApiService::class.java) }
}
run
fun main() = runBlocking {
val rs = marsApiService.getPhotos()
println(rs)
}
In your code, retrofit by lazy reference not resolved cause of retrofit is property of class, move the retrofit globally like using (Companion) object or like code2 (highest hierarchy?)

Answer 2

Hope this link
make you clear the difference between object and companion object and when to use them. Happy learning

Answer 3

It was the same problem that I had.
I solved it just excluding the class MarsApiService
I didn´t use companion object too.
The right code is below
import retrofit2.Retrofit
import retrofit2.converter.scalars.ScalarsConverterFactory
import retrofit2.http.GET
private const val BASE_URL = "https://android-kotlin-fun-mars-server.appspot.com"
public val retrofit = Retrofit.Builder()
.addConverterFactory(ScalarsConverterFactory.create())
.baseUrl(Companion.BASE_URL)
.build()
interface MarsApiService{
#GET("photos")
fun getPhotos(): String
}
object MarsApi {
val retrofitService: MarsApiService by lazy {
retrofit.create(MarsApiService::class.java)
}
}