Usman khan Usman khan - 1 month ago 24
Android Question

Unsupported operation: Android, Retrofit, OkHttp. Adding interceptor in OkHttpClient

I am trying to add token based authentication via Retrofit 2.0-beta3 and OkHttpClient in Android using interceptors. But I get UnsupportedOperationException when I add my interceptor in OkHttpClient.
Here is my code:
In ApiClient.java

public static TrequantApiInterface getClient(final String token) {
if( sTreqantApiInterface == null) {

Log.v(RETROFIT_LOG, "Creating api client for the first time");
OkHttpClient okClient = new OkHttpClient();

okClient.interceptors().add(new Interceptor() {
@Override
public Response intercept(Interceptor.Chain chain) throws IOException {
Request original = chain.request();

// Request customization: add request headers
Request.Builder requestBuilder = original.newBuilder()
.header("Authorization", token)
.method(original.method(), original.body());

Request request = requestBuilder.build();
return chain.proceed(request);
}
});

Retrofit client = new Retrofit.Builder()
.baseUrl(baseUrl)
.client(okClient)
.addConverterFactory(GsonConverterFactory.create())
.build();
sTreqantApiInterface = client.create(TrequantApiInterface.class);
}
return sTreqantApiInterface;
}


And I use it like:

private void ampFreqTest(){
String token = getSharedPreferences(getString(R.string.preference_file_key), Context.MODE_PRIVATE)
.getString(getString(R.string.key_token), "");

service = ApiClient.getClient(token);
//I get an exception on this line:
Call<List<AmpFreq>> call = service.getUserAmpFreq("1");
call.enqueue(new Callback<List<AmpFreq>>() {
@Override
public void onResponse(Response<List<AmpFreq>> response) {
Toast.makeText(HomeScreen.this, "Got result", Toast.LENGTH_LONG);

Log.v(ApiClient.RETROFIT_LOG, "Success api client." + response.message());
Log.v(ApiClient.RETROFIT_LOG, "Success api client.");
}
@Override
public void onFailure(Throwable t) {
Toast.makeText(HomeScreen.this, t.getMessage() , Toast.LENGTH_LONG);
Log.v(ApiClient.RETROFIT_LOG, "Fail api client." + t.getMessage() );
}
});
}


But I get this error:

Process: com.trequant.usman.trequant_android, PID: 14400
java.lang.UnsupportedOperationException at java.util.Collections$UnmodifiableCollection.add(Collections.java:932)
at com.trequant.usman.trequant_android.api.ApiClient.getClient(ApiClient.java:41)


It gives me error on adding a new interceptor saying that it is not modifiableCollection but the documentation for interceptors() function says: /**

* Returns a modifiable list of interceptors that observe the full span of each call: from before
* the connection is established (if any) until after the response source is selected (either the
* origin server, cache, or both).
*/


What am I doing wrong? Could it be a bug?

Answer

This issue occurs when you change Retrofit 2.0-beta2 to Retrofit 2.0-beta3. You have to use builder if you want to create OkHttpClient object.

Change :

 OkHttpClient okClient = new OkHttpClient();

 okClient.interceptors().add(new Interceptor() {
       @Override
       public Response intercept(Interceptor.Chain chain) throws IOException {
            Request original = chain.request();

            // Request customization: add request headers
            Request.Builder requestBuilder = original.newBuilder()
                    .header("Authorization", token)
                    .method(original.method(), original.body());

            Request request = requestBuilder.build();
            return chain.proceed(request);
        }
 });

to :

 OkHttpClient okClient = new OkHttpClient.Builder()
           .addInterceptor(
               new Interceptor() {
                 @Override
                 public Response intercept(Interceptor.Chain chain) throws IOException {
                       Request original = chain.request();

                       // Request customization: add request headers
                       Request.Builder requestBuilder = original.newBuilder()
                               .header("Authorization", token)
                               .method(original.method(), original.body());

                       Request request = requestBuilder.build();
                       return chain.proceed(request);
                   }
               })
           .build();

It should resolve your problem.