CODEWITHSUNDEEP
javarestretrofitsimple-framework
rmuller
rmuller

Reputation: 12849

Unable to create call adapter for class example.Simple

I am using retrofit 2.0.0-beta1 with SimpleXml. I want the retrieve a Simple (XML) resource from a REST service. Marshalling/Unmarshalling the Simple object with SimpleXML works fine.

When using this code (converted form pre 2.0.0 code):

final Retrofit rest = new Retrofit.Builder()
    .addConverterFactory(SimpleXmlConverterFactory.create())
    .baseUrl(endpoint)
    .build();
SimpleService service = rest.create(SimpleService.class);
LOG.info(service.getSimple("572642"));

Service:

public interface SimpleService {

    @GET("/simple/{id}")
    Simple getSimple(@Path("id") String id);

}

I get this exception:

Exception in thread "main" java.lang.IllegalArgumentException: Unable to create call adapter for class example.Simple
    for method SimpleService.getSimple
    at retrofit.Utils.methodError(Utils.java:201)
    at retrofit.MethodHandler.createCallAdapter(MethodHandler.java:51)
    at retrofit.MethodHandler.create(MethodHandler.java:30)
    at retrofit.Retrofit.loadMethodHandler(Retrofit.java:138)
    at retrofit.Retrofit$1.invoke(Retrofit.java:127)
    at com.sun.proxy.$Proxy0.getSimple(Unknown Source)

What am i missing? I know that wrapping the return type by a Call works. But I want the service to return business objects as type (and working in sync mode).

UPDATE

After added the extra dependancies and .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) as suggested by different answers, I still get this error:

Caused by: java.lang.IllegalArgumentException: Could not locate call adapter for class simple.Simple. Tried:
 * retrofit.RxJavaCallAdapterFactory
 * retrofit.DefaultCallAdapter$1

Upvotes: 205

Views: 192661

Answers (20)

yagizsenal
yagizsenal

Reputation: 105

In my case it was working on the debug version but crashing in the release version. I fixed it by updating my proguard-rules.pro file with:

-keep class retrofit2.** { *; }

Upvotes: 6

Merkost
Merkost

Reputation: 2376

I used Coroutines with CoroutineCallAdapterFactory, but accidentally forgot to make the function suspend. Hope it helps someone!

Upvotes: 57

lucas rivaldo
lucas rivaldo

Reputation: 181

For this case :

val apiService = RetrofitFactory.makeRetrofitService()

CoroutineScope(Dispatchers.IO).launch {

    val response = apiService.myGetRequest()

    // process response...

}

interface ApiService {

   @GET("/my-get-request")
   suspend fun myGetRequest(): Response<String>
}

All methods used within suspend functions must be marked as suspend because of it's manageability by the Corountine. Check more info here.

So if you dont mark your API service function as suspend when you call it inside a CoroutineScope or any suspend marked method, android app crashes and throws the Exception in thread "main" java.lang.IllegalArgumentException: Unable to create call adapter for class example.class error.

Upvotes: 18

Gopal Singh Sirvi
Gopal Singh Sirvi

Reputation: 4649

If your API interface is returning Response object then probably you forgot to add suspend function in your API interface.

API Interface

interface WeatherAPI {
    @GET("/data/2.5/weather")
    suspend fun getWeatherInfo(
        @Query("q") query: String
    ): Response<WeatherResponse>
}

Repository

class WeatherRepositoryImpl @Inject constructor(
private val weatherAPI: WeatherAPI
) : WeatherRepository {
    override suspend fun getWeatherInfo(query: String): Resource<WeatherResponse> {
        try {
            val response = weatherAPI.getWeatherInfo(query)
            if (response.isSuccessful) {
                response.body()?.let {
                    return Resource.success(it)
                } ?: return Resource.error("Unknown error occurred", null)
            } else {
                return Resource.error("Unknown error occured", null)
            }
        } catch (e: Exception) {
            return Resource.error("Please check your internet connection", null)
        }
    }

}

Upvotes: 0

NELSON RODRIGUEZ
NELSON RODRIGUEZ

Reputation: 369

I solved by update retrofit version to 2.9.0 in gradle

Upvotes: 0

Ticherhaz FreePalestine
Ticherhaz FreePalestine

Reputation: 2377

I have found a solution, in my situation is, I am using ApiInterface.java from JAVA to connect with the MyViewModel.ktwhich is from KOTLIN.

  1. This is ApiInterface.java

    @GET(Constant.CONNECTION) Call<com.example.kt.model.ConnectionResponse> ConnectionKt();

  2. You need to create a new Kotlin class, named as ApiTemporary.kt

    class ApiTemporary( private val apiInterface: ApiInterface = RetrofitClient.getRetrofitInstance().create(ApiInterface::class.java) ) {

    suspend fun getConnectionKt(): Response { return apiInterface.ConnectionKt().awaitResponse() } }

  3. So lastly, at MyViewModel.kt, you can do like this

val data = withContext(ioDispatcher) { val result = apiTemporary.getConnectionKt() if (result.isSuccessful) { Resource.Success(result.body()) } else { Resource.Error("Server error. Please try again") } } _connection.value = data

So, the ApiTemporary will help to convert them from Java to Kotlin which is usage of Coroutines

Upvotes: 0

chatlanin
chatlanin

Reputation: 6105

In case of Kotlin and coroutines this situation happened when I forgot to mark api service function as suspend when I call this function from CoroutineScope(Dispatchers.IO).launch{}:

Usage:

    val apiService = RetrofitFactory.makeRetrofitService()

    CoroutineScope(Dispatchers.IO).launch {

        val response = apiService.myGetRequest()

        // process response...

    }

ApiService.kt

interface ApiService {

       @GET("/my-get-request")
       suspend fun myGetRequest(): Response<String>
}

Upvotes: 547

ItSNeverLate
ItSNeverLate

Reputation: 729

IllegalArgumentException: Unable to create call adapter for class java.lang.Object

Short answer: I have solved it by the following changes

ext.retrofit2Version = '2.4.0' -> '2.6.0'
implementation"com.squareup.retrofit2:retrofit:$retrofit2Version"
implementation "com.squareup.retrofit2:adapter-rxjava2:$retrofit2Version"
implementation "com.squareup.retrofit2:converter-gson:$retrofit2Version"

Good luck

Upvotes: 12

Johannes Barop
Johannes Barop

Reputation: 7796

If you are not using RxJava it properly makes no sense to add RxJava just for retrofit. 2.5.0 has support for CompletableFuture built in which you can use without adding any other library or adapter.

build.gradle.kts

implementation("com.squareup.retrofit2:retrofit:2.5.0")
implementation("com.squareup.retrofit2:retrofit-converters:2.5.0")

Api.kt

interface Api {
    @GET("/resource")
    fun listCompanies(): CompletableFuture<ResourceDto>
}

Usage:

Retrofit.Builder()
   .addConverterFactory(SimpleXmlConverterFactory.create())
   .baseUrl("https://api.example.com")
   .build()
   .create(Api::class.java)

Upvotes: 3

svkaka
svkaka

Reputation: 4022

In my case I used 

com.squareup.retrofit2:adapter-rxjava:2.5.0 //notice rxjava

instead of 

com.squareup.retrofit2:adapter-rxjava2:2.5.0 //notice rxjava2

you should be using com.squareup.retrofit2:adapter-rxjava2:2.5.0 when using io.reactivex.rxjava2

Upvotes: 1

Syed Waqas
Syed Waqas

Reputation: 11

public interface SimpleService {

  @GET("/simple/{id}")
  Simple getSimple(@Path("id") String id);

}

Communication with the network is done with the separate thread so you should change your Simple with that.

public interface SimpleService {

  @GET("/simple/{id}")
  Call<Simple> getSimple(@Path("id") String id);

}

Upvotes: 1

Nick Cardoso
Nick Cardoso

Reputation: 21733

Just to make the Call examples clearer for people who are migrating, not using Rx, or who want synchronous calls - Call essentially replaces (wraps) Response, meaning:

Response<MyObject> createRecord(...);

becomes 

Call<MyObject> createRecord(...);

and not 

Call<Response<MyObject>> createRecord(...);

(which will still require an adapter)

The Call will then allow you to still use isSuccessful as it actually returns a Response. So you can do something like:

myApi.createRecord(...).execute().isSuccessful()

Or access your Type (MyObject) like:

MyObject myObj = myApi.createRecord(...).execute().body();

Upvotes: 2

Mateusz Korwel
Mateusz Korwel

Reputation: 1148

If you want use retrofit2 and you don't want always return retrofit2.Call<T>, you have to create your own CallAdapter.Factory which return simple type as you expected. The simple code can look like this:

import retrofit2.Call;
import retrofit2.CallAdapter;
import retrofit2.Retrofit;

import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

public class SynchronousCallAdapterFactory extends CallAdapter.Factory {
    public static CallAdapter.Factory create() {
        return new SynchronousCallAdapterFactory();
    }

    @Override
    public CallAdapter<Object, Object> get(final Type returnType, Annotation[] annotations, Retrofit retrofit) {
        // if returnType is retrofit2.Call, do nothing
        if (returnType.toString().contains("retrofit2.Call")) {
            return null;
        }

        return new CallAdapter<Object, Object>() {
            @Override
            public Type responseType() {
                return returnType;
            }

            @Override
            public Object adapt(Call<Object> call) {
                try {
                    return call.execute().body();
                } catch (Exception e) {
                    throw new RuntimeException(e); // do something better
                }
            }
        };
    }
}

Then simple register the SynchronousCallAdapterFactory in Retrofit should solved your problem.

Retrofit rest = new Retrofit.Builder()
        .baseUrl(endpoint)
        .addConverterFactory(SimpleXmlConverterFactory.create())
        .addCallAdapterFactory(SynchronousCallAdapterFactory.create())
        .build();

After that you can return simple type without retrofit2.Call.

public interface SimpleService {
    @GET("/simple/{id}")
    Simple getSimple(@Path("id") String id);
}

Upvotes: 19

H&#252;seyin B&#252;lb&#252;l
H&#252;seyin B&#252;lb&#252;l

Reputation: 187

in my case using this 

compile 'com.jakewharton.retrofit:retrofit2-rxjava2-adapter:1.0.0'

with this 

new Retrofit.Builder().addCallAdapterFactory(RxJava2CallAdapterFactory.create())...

solved the problem when nothing else worked

Upvotes: 4

rahul.ramanujam
rahul.ramanujam

Reputation: 5618

Add the following dependencies for retrofit 2

 compile 'com.squareup.retrofit2:retrofit:2.1.0'

for GSON

 compile 'com.squareup.retrofit2:converter-gson:2.1.0'

for observables

compile 'com.squareup.retrofit2:adapter-rxjava:2.1.0'

In your case for XML , you would have to include the following dependencies

 compile 'com.squareup.retrofit2:converter-simplexml:2.1.0'

Update the service call as below 

final Retrofit rest = new Retrofit.Builder()
    .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
    .addConverterFactory(SimpleXmlConverterFactory.create())
    .baseUrl(endpoint)
    .build();
SimpleService service = rest.create(SimpleService.class);

Upvotes: 13

Sithu
Sithu

Reputation: 4421

You can implement a Callback, get the Simple from onResponse function.

public class MainActivity extends Activity implements Callback<Simple> {

    protected void onCreate(Bundle savedInstanceState) {
        final Retrofit rest = new Retrofit.Builder()
                    .addConverterFactory(SimpleXmlConverterFactory.create())
                    .baseUrl(endpoint)
                    .build();
        SimpleService service = rest.create(SimpleService.class);
        Call<Simple> call = service.getSimple("572642");
        //asynchronous call
        call.enqueue(this);

        return true;
    }

    @Override
    public void onResponse(Response<Simple> response, Retrofit retrofit) {
       // response.body() has the return object(s)
    }

    @Override
    public void onFailure(Throwable t) {
        // do something
    }

}

Upvotes: 0

Hosam Aly
Hosam Aly

Reputation: 42443

Short answer: return Call<Simple> in your service interface.

It looks like Retrofit 2.0 is trying to find a way of creating the proxy object for your service interface. It expects you to write this:

public interface SimpleService {
    @GET("/simple/{id}")
    Call<Simple> getSimple(@Path("id") String id);
}

However, it still wants to play nice and be flexible when you don't want to return a Call. To support this, it has the concept of a CallAdapter, which is supposed to know how to adapt a Call<Simple> into a Simple.

The use of RxJavaCallAdapterFactory is only useful if you are trying to return rx.Observable<Simple>.

The simplest solution is to return a Call as Retrofit expects. You could also write a CallAdapter.Factory if you really need it.

Upvotes: 93

shichaohui
shichaohui

Reputation: 579

add dependencies:

compile 'com.squareup.retrofit:retrofit:2.0.0-beta1'
compile 'com.squareup.retrofit:adapter-rxjava:2.0.0-beta1'
compile 'com.squareup.retrofit:converter-gson:2.0.0-beta1'

create your adapter this way:

Retrofit rest = new Retrofit.Builder()
    .baseUrl(endpoint)
    .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
    .addConverterFactory(SimpleXmlConverterFactory.create())
    .build();

addCallAdapterFactory () and addConverterFactory () both need to be called.

Service:

public interface SimpleService {

    @GET("/simple/{id}")
    Call<Simple> getSimple(@Path("id") String id);

}

Modify Simple to Call<Simple>.

Upvotes: 57

Rensodarwin
Rensodarwin

Reputation: 286

The way I fixed this issue was adding this to the application gradle file, if the configuration is not set there will be conflicts, maybe this will be fixed in the stable release of the library:

configurations {
    compile.exclude group: 'stax'
    compile.exclude group: 'xpp3'
}

dependencies {
    compile 'com.squareup.retrofit:retrofit:2.0.0-beta1'
    compile 'com.squareup.retrofit:converter-simplexml:2.0.0-beta1'
}

and create your adapter this way:

  Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(endPoint)
            .addConverterFactory(SimpleXmlConverterFactory.create())
            .build();

Hope it helps!

Upvotes: -2

Himanshu Virmani
Himanshu Virmani

Reputation: 2460

With the new Retrofit(2.+) you need to add addCallAdapterFactory which can be a normal one or a RxJavaCallAdapterFactory(for Observables). I think you can add more than both too. It automatically checks which one to use. See a working example below. You can also check this link for more details. 

 Retrofit retrofit = new Retrofit.Builder().baseUrl(ApiConfig.BASE_URL)
        .addConverterFactory(GsonConverterFactory.create())
        .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
        .build()

Upvotes: 39

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