Multipart request with Retrofit @PartMap Error in Kotlin (Android)

Question

If I am using this code in Java then its working fine. When I convert that code in kotlin then I got Error.

Logcat

08-20 23:46:51.003 3782-3782/com.qkangaroo.app W/System.err: java.lang.IllegalArgumentException: Parameter type must not include a type variable or wildcard: java.util.Map (parameter #1) 08-20 23:46:51.003 3782-3782/com.qkangaroo.app W/System.err: for method ApiInterface.updateCustomerDetail 08-20 23:46:51.003 3782-3782/com.qkangaroo.app W/System.err: at retrofit2.ServiceMethod$Builder.methodError(ServiceMethod.java:752) 08-20 23:46:51.004 3782-3782/com.qkangaroo.app W/System.err: at retrofit2.ServiceMethod$Builder.methodError(ServiceMethod.java:743) 08-20 23:46:51.004 3782-3782/com.qkangaroo.app W/System.err: at retrofit2.ServiceMethod$Builder.parameterError(ServiceMethod.java:761) 08-20 23:46:51.004 3782-3782/com.qkangaroo.app W/System.err: at retrofit2.ServiceMethod$Builder.build(ServiceMethod.java:195) 08-20 23:46:51.004 3782-3782/com.qkangaroo.app W/System.err: at retrofit2.Retrofit.loadServiceMethod(Retrofit.java:170) 08-20 23:46:51.005 3782-3782/com.qkangaroo.app W/System.err: at retrofit2.Retrofit$1.invoke(Retrofit.java:147) 08-20 23:46:51.005 3782-3782/com.qkangaroo.app W/System.err: at $Proxy0.updateCustomerDetail(Native Method) 08-20 23:46:51.005 3782-3782/com.qkangaroo.app W/System.err: at com.qkangaroo.app.Fragments.MoreScreen.MoreFragment.updateProfile(MoreFragment.kt:261) 08-20 23:46:51.006 3782-3782/com.qkangaroo.app W/System.err: at com.qkangaroo.app.Fragments.MoreScreen.MoreFragment$clickListener$1.onClick(MoreFragment.kt:191) 08-20 23:46:51.006 3782-3782/com.qkangaroo.app W/System.err: at android.view.View.performClick(View.java:3517) 08-20 23:46:51.006 3782-3782/com.qkangaroo.app W/System.err: at android.view.View$PerformClick.run(View.java:14155) 08-20 23:46:51.006 3782-3782/com.qkangaroo.app W/System.err: at android.os.Handler.handleCallback(Handler.java:605) 08-20 23:46:51.007 3782-3782/com.qkangaroo.app W/System.err: at android.os.Handler.dispatchMessage(Handler.java:92) 08-20 23:46:51.007 3782-3782/com.qkangaroo.app W/System.err: at android.os.Looper.loop(Looper.java:154) 08-20 23:46:51.007 3782-3782/com.qkangaroo.app W/System.err: at android.app.ActivityThread.main(ActivityThread.java:4624) 08-20 23:46:51.008 3782-3782/com.qkangaroo.app W/System.err: at java.lang.reflect.Method.invokeNative(Native Method) 08-20 23:46:51.009 3782-3782/com.qkangaroo.app W/System.err: at java.lang.reflect.Method.invoke(Method.java:511) 08-20 23:46:51.009 3782-3782/com.qkangaroo.app W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809) 08-20 23:46:51.010 3782-3782/com.qkangaroo.app W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576) 08-20 23:46:51.011 3782-3782/com.qkangaroo.app W/System.err: at dalvik.system.NativeStart.main(Native Method)

fragment.kt

    var map:HashMap<String,RequestBody> = HashMap<String, RequestBody>()
    map.put("version",ApiClient.createRequestBody(AppConstants.API_VERSION))
    map.put("auth_token", ApiClient.createRequestBody(customer.authToken!!))
    map.put("customer_name",ApiClient.createRequestBody(profileName))
    map.put("email", ApiClient.createRequestBody(profileEmail))

    val apiInterface = ApiClient.client.create(ApiInterface::class.java)

    val updateCustomerCall: Call<UpdateCustomer> = apiInterface.updateCustomerDetail(map)
    updateCustomerCall.enqueue(object : Callback<UpdateCustomer> {
        override fun onResponse(call: Call<UpdateCustomer>?, response: Response<UpdateCustomer>?) {

        }

        override fun onFailure(call: Call<UpdateCustomer>?, t: Throwable?) {
            utilities!!.hideProgress(progress)
        }
    })

ApiClient.kt

val MULTIPART_FORM_DATA = "multipart/form-data"

fun createRequestBody(s: String): RequestBody {
    return RequestBody.create(
            MediaType.parse(MULTIPART_FORM_DATA), s)
}

ApiInterface,.kt

@Multipart
@POST("customer")
fun updateCustomerDetail(@PartMap map: Map<String,RequestBody >): Call<UpdateCustomer>

Gradle file

implementation "com.squareup.okhttp3:okhttp:3.8.1"
implementation "com.squareup.okhttp3:logging-interceptor:3.8.1"
implementation ("com.squareup.retrofit2:retrofit:2.3.0"){
     exclude module: 'okhttp'
}
implementation "com.squareup.retrofit2:converter-gson:2.3.0"

Answer 1

Add @JvmSuppressWildcards before RequestBody

fun updateCustomerDetail(@PartMap map: Map<String, @JvmSuppressWildcards RequestBody >): Call<UpdateCustomer>

Answer 2

Use HashMap or MutableMap instead of Map< K, out V> for the PartMap

An alternative way works fine for me. Mentioned by alex-tpom6oh in Retrofi Kotlin Issue

I think it's happening because the Map declaration is public interface Map< K, out V> and the out word makes the value type generic. You can try to use MutableMap or HashMap instead.

@Multipart
@POST("customer")
fun updateCustomerDetail(@PartMap map: HashMap<String, RequestBody>): Call<UpdateCustomer>