无法为 retrofit2.Response<...> 创建调用适配器

Question

My Api:

@GET("/cinema/notShownMovies")
fun getNotShownMovies(
   @Query("token") token: String
): Response<GetMovieResponse>

Exception when trying to call API:

java.lang.IllegalArgumentException: Unable to create call adapter for retrofit2.Response<...data.GetMovieResponse> for method InstanceApi.getNotShownMovies Unable to create call adapter for retrofit2.Response<...data.GetMovieResponse> for method InstanceApi.getNotShownMovies

I don't know where to start. All other API calls work fine which is also defined in the same API class. Maybe a model error?

Answer 1

Just add suspend modifier if using coroutines . This will solve the problem.

Otherwise your issue is likely because there is no Call adapter added when instantiating your Retrofit object. For example, for RxJava2 , you can include a call adapter by adding this line while building it.

.addCallAdapterFactory(RxJava2CallAdapterFactory.createWithScheduler(Schedulers.io()))

Answer 2

In the Gradle file add this line inside of release buildTyps

• minifyEnabled false

Answer 3

I had a similar crash IllegalArgumentException: Call return type must be parameterized as Call .

Crash log:

Caused by: java.lang.IllegalArgumentException: Unable to create call adapter for interface retrofit2.Call
    for method Api.login
    at retrofit2.Utils.methodError(Utils.java:54)
    at retrofit2.HttpServiceMethod.createCallAdapter(HttpServiceMethod.java:116)
    at retrofit2.HttpServiceMethod.parseAnnotations(HttpServiceMethod.java:67)
    at retrofit2.ServiceMethod.parseAnnotations(ServiceMethod.java:39)
    at retrofit2.Retrofit.loadServiceMethod(Retrofit.java:202)
    at retrofit2.Retrofit$1.invoke(Retrofit.java:160)
    at java.lang.reflect.Proxy.invoke(Proxy.java:1006)
    at $Proxy0.login(Unknown Source)
    at <redacted>.screen.login.LoginActivity.onSignInClick(LoginActivity.java:103)
    ... 13 more
Caused by: java.lang.IllegalArgumentException: Call return type must be parameterized as Call<Foo> or Call<? extends Foo>
    at retrofit2.DefaultCallAdapterFactory.get(DefaultCallAdapterFactory.java:42)
    at retrofit2.Retrofit.nextCallAdapter(Retrofit.java:253)
    at retrofit2.Retrofit.callAdapter(Retrofit.java:237)
    at retrofit2.HttpServiceMethod.createCallAdapter(HttpServiceMethod.java:114)
    ... 20 more

I found out it was crashing because of Proguard/R8. Proguard was renaming Retrofit classes and to fix it I updated the Proguard settings with:

-dontwarn retrofit2.**
-keep class retrofit2.** { *; }